United States

Department of

Agriculture

Agricultural

Marketing 

Service

Transportation and

Marketing Programs

Handbook

Number 669

September 1995

Reprinted July 2008 

Protecting

Perishable Foods

During Transport by Truck
B
i

Protecting Perishable Foods 

During Transport by Truck

by B. Hunt Ashby 

Agricultural Marketing Service

Transportation and Marketing Programs

September 1995

Reprinted July 2008

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race,

color, national origin, age, disability, and where applicable, sex,

marital status, familial status, parental status, religion, sexual

orientation, genetic information, political beliefs, reprisal, or

because all or part of an individual’s income is derived from any

public assistance program. (Not all prohibited bases apply to all

programs.) Persons with disabilities who require alternative

means for communication of program information (Braille,

large print, audiotape, etc.) should contact USDA’s TARGET

Center at (202) 720–2600 (voice and TDD). 

To file a complaint of discrimination, write to USDA, Director,

Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250–9410, or call (800) 795–3272 (voice) or

(202) 720–6382 (TDD). USDA is an equal opportunity

provider and employer.

iii

Contents

Introduction

I. Important Factors in Protection of Perishable Foods

Refrigeration ....................................................................................................................1

Refrigeration Methods ....................................................................................................2

Mechanical Refrigeration ..........................................................................................2

Ice ..............................................................................................................................3

Cryogenic Refrigerants ..............................................................................................3

Trailer Design and Construction......................................................................................4

Insulation ....................................................................................................................4

Air Circulation Systems ............................................................................................4

Multi-temperature Vehicles ........................................................................................6

Humidity ..........................................................................................................................7

Precooling the Product ....................................................................................................8

Freezing and Chilling Injury............................................................................................9

Controlled and Modified Atmospheres..........................................................................11

II. Preparation for Loading

Adequacy of Equipment ................................................................................................13

Cleaning and Sanitation ................................................................................................13

Vehicle Maintenance......................................................................................................13

Precooling or Prewarming of the Vehicle......................................................................16

Preloading Checklist......................................................................................................16

III. Loading Considerations

Type of Air Delivery......................................................................................................17

Type of Shipping Container ..........................................................................................17

Whether Frozen or Nonfrozen ......................................................................................18

Bracing Needs................................................................................................................18

Compatibility of Mixed Loads ......................................................................................18

Whether Palletized or Unitized......................................................................................19

Length of Transit Period................................................................................................19

IV. Loading and Load Patterns

Basic Terminology ........................................................................................................20

Loading Vehicles with Top-air Delivery........................................................................20

Hand-stacked Loads ................................................................................................20

Unit Loads................................................................................................................22

Loading Vehicles with Bottom-air Delivery..................................................................22

Unit or Pallet Loads ......................................................................................................24

Vented Loads..................................................................................................................24

Top-iced Loads ..............................................................................................................24

Loading Checklist..........................................................................................................27

V. Individual Commodity Requirements

Fresh Fruits and Vegetables ..........................................................................................28

Apples ......................................................................................................................28

Apricots ....................................................................................................................29
iv

Artichokes ................................................................................................................29

Asparagus ................................................................................................................29

Avocados ..................................................................................................................30

Bananas ....................................................................................................................30

Beans (green, snap, or pole) ....................................................................................31

Beans (lima, in pods)................................................................................................31

Beets ........................................................................................................................31

Beet Tops ..................................................................................................................32

Blackberries..............................................................................................................32

Blueberries................................................................................................................32

Broccoli ....................................................................................................................33

Brussels Sprouts ......................................................................................................34

Cabbage ....................................................................................................................34

Cantaloupes ..............................................................................................................35

Carrots ......................................................................................................................35

Cauliflower ..............................................................................................................35

Celery........................................................................................................................36

Cherries ....................................................................................................................36

Corn (sweet) ............................................................................................................37

Cranberries................................................................................................................38

Cucumbers................................................................................................................38

Eggplants ..................................................................................................................39

Endive and Escarole ................................................................................................39

Garlic (dry) ..............................................................................................................39

Grapefruit..................................................................................................................40

Grapes ......................................................................................................................40

Kale ..........................................................................................................................41

Kiwi Fruit ................................................................................................................41

Lemons ....................................................................................................................42

Lettuce (head) ..........................................................................................................42

Lettuce (leaf) ............................................................................................................42

Limes ........................................................................................................................43

Mangoes....................................................................................................................43

Melons (Honeydew, Casaba, Crenshaw, Persian)....................................................43

Mushrooms ..............................................................................................................44

Okra ..........................................................................................................................44

Onions (green), Shallots, and Leeks ........................................................................45

Onions (dry bulbs)....................................................................................................45

Oranges ....................................................................................................................45

Parsley.......................................................................................................................46

Parsnips ....................................................................................................................46

Peaches and Nectarines............................................................................................47

Pears..........................................................................................................................47

Peas (green and snow peas in pods) ........................................................................47

Peppers (sweet) ........................................................................................................48

Pineapples ................................................................................................................48

Plums and Fresh Prunes ..........................................................................................48

Potatoes ....................................................................................................................49

Radishes....................................................................................................................50

Raspberries ..............................................................................................................51

Rhubarb ....................................................................................................................51

Romaine Lettuce ......................................................................................................51

Salad Mixes..............................................................................................................52
v

Spinach ......................................................................................................................52

Squash and Pumpkins................................................................................................53

Strawberries ..............................................................................................................53

Sweet Potatoes ..........................................................................................................54

Tangerines..................................................................................................................54

Tomatoes (mature-green) ..........................................................................................54

Tomatoes (pink) ........................................................................................................55

Watermelons ..............................................................................................................55

Canned Foods................................................................................................................57

Dairy Products ..............................................................................................................60

Butter and Margarine ................................................................................................60

Cheeses......................................................................................................................60

Ice Cream ..................................................................................................................61

Fresh and Cured Meat and Fresh Seafood....................................................................62

Boxed Meats..............................................................................................................62

Carcass Meats............................................................................................................62

Frozen Foods ................................................................................................................66

Poultry and Eggs ..........................................................................................................68

Poultry (fresh and hard-chilled) ................................................................................68

Shell Eggs..................................................................................................................68

Appendix I........................................................................................................................71

Estimating Mobile Refrigeration Requirements ..........................................................71

Sample Refrigeration Requirement Calculation ..........................................................76

Appendix II......................................................................................................................78

Load Compatibility Groups..........................................................................................78

Appendix III ....................................................................................................................83

Recommended Protective Services for Perishable Foods During Transit....................83

Selected Bibliography......................................................................................................87

Other Resources ..............................................................................................................88
vi

List of Tables

Table 1. — Heat Absorption Characteristics of Certain Refrigeration Mediums

Table 2. — Sensitivity of Some Fruits and Vegetables to Freezing

Table 3. — Some Fruits and Vegetables Subject to Chilling Injury at Above-freezing 

Temperatures

Table 4. — Freezing Temperatures of Selected Canned Foods

Table 5. — Ideal Temperature Ranges for Transporting Common Types of Cheeses 

Table 6. — Recommended Temperatures and Humidities for Protecting Selected Fresh,

Cured, and Processed Meat and Seafood Products During Transit 

Table I-1.— Specific Heat Above and Below Freezing for Certain Perishable Products 

Table I-2.— Approximate Amount of Respiration Heat Produced by Certain Fruits 

and Vegetables at the Specific Temperatures
vii

List of Figures

1. Depletion of sucrose or sugar in sweet corn with increase in holding temperature.

2. Pathways of air in a trailer with a top-air delivery system. 

3. Pathways of air in a trailer with a bottom-air delivery system.

4. Features essential for maintaining the critical airflow chain in trailers with 

top-air delivery.

5. Effect of different floor configurations on return-air space under the load.

6. A typical multi-temperature mechanically refrigerated trailer.

7. Methods of loading to reduce contact of products with walls and to reduce the chance

of freezing or chilling injury in extremely cold weather: (a) crosswise-offset stacking of

boxes or crates, (b) pyramid stacking of bagged products, and (c) center-loading of palletized loads.

8. Location of NPLA/RTF certification plates and decals which provide information 

on refrigeration rating and optional equipment on refrigerated trailers at time of 

manufacture.

9. Dimensional view of a load in a truck semi-trailer showing arrangements of containers

in rows, stacks, and layers.

10. A typical airflow loading pattern for commodities packed in fiberboard boxes: 

(a) longitudinal view, (b) header stack, and (c) rear view of all other stacks.

11. Rear view of an airflow loading pattern modified for wirebound crates. 

12. End and overhead views of basic pallet or unit load patterns in a semi-trailer: 

(a) airflow, (b) center-loaded, (c) wall-loaded, (d) off-set against walls, and (e) pinwheel. (Note: Pallets used in pinwheel patterns must be 4-way or air flow under the

load will be blocked.) 

13. Effect of different unit load patterns on the percentage of cartons contacting the floor

and walls in a typical load of a perishable product.

14. Example of strapping and corner boards on a unit load.
viii

15. Example of a method for bracing a load at the rear doors.

16. Rear view of a stacking pattern with horizontal wood stabilizing strips for top-iced

loads in wirebound crates (shown) or waxed fiberboard boxes.

17. A palletized load of strawberries, center-loaded. (Note: Each pallet load is enclosed 

in an airtight plastic bag injected with a modified atmosphere.)

18. A mixed palletized load of celery and green onions loaded in a unit load 

airflow pattern.

19. Side (a) and end (b) views of a mixed load of hanging forequarters and hindquarters of

beef.

20. A palletized load of eggs. Note the stretch film around the pallet loads at the rear door

area where road shock is greatest. 
ix

Preface

This is a revision of handbook No. 669 published in 1987. It superseded Agriculture

Handbook No. 105, “Protecting Perishable

Foods During Transport by Motortruck,”

first published in 1956 and revised in 1970.

These handbooks have been extremely popular, and tens of thousands of copies have

been distributed worldwide. 

This updated edition reflects the dynamic

changes and innovations in the handling and

transportation of perishable foods. Some of

these are the rapid change from handstacked loads to unitized loads on pallets

and slipsheets, the use of microprocessors

for more efficient refrigeration, and the use

of satellites to monitor and control the performance of refrigerated vehicles during

transit.

Many individuals and organizations provided information or other assistance in revising this handbook. Special recognition goes

to W.L. Craig of USDA’s Agricultural Marketing Service for preparing the illustrations, and to L.A. Risse of USDA’s Agricultural Research Service for reviewing this

publication. A great deal of the information

on recommended holding requirements for

fresh fruits and vegetables is from USDA

Handbook No. 66 The Commercial Storage

of Fruits, Vegetables, and Florist and Nursery Stocks, cited in the bibliography.

1

temperatures cause loss of vitamin C in

asparagus, and sugar or sucrose depletion in

fresh sweet corn (figure 1). Low temperatures

can cause chilling injury to fresh fruits and

vegetables. This may not show up until the

product is at the retail store or on the consumer’s table, where failure to ripen properly,

off-flavors, discoloration, pitting, and other

signs of poor quality may be evident.

Refrigeration removes excess heat and provides temperature control for food products in

transport vehicles. Heat is a positive and measurable form of energy that always radiates or

flows toward the cold or refrigeration source. 

In the United States, heat is measured in

British thermal units (Btu). The Btu is defined

as the amount of heat required to raise the

Refrigeration

The object of refrigerating food products is

to maintain quality and prolong shelf life by

keeping the product temperature at the point

where metabolic and microbial deterioration

are minimized. Maintaining the desired or

ideal holding temperature is a major factor

in protecting perishable foods against quality loss during storage and distribution. Quality loss is a function of both time and temperature abuse. Abuse is additive and, even

for short periods of time during loading,

transit, and unloading, may cause a considerable amount of quality loss by the time the

product reaches its destination. 

Abuse can result from temperatures that are

either too high or too low. For example, high

I. Important Factors in Protection of Perishable Foods

Figure 1. Depletion of

sucrose or sugar in

sweet corn with increase

in holding temperature. LOSS IN INITIAL SUCROSE (PERCENT)

DAYS IN STORAGE

OoC

(32oF)

1OoC

(50o 2OoC F)

(68oF)

3OoC

(86oF)

O 1 2 34

8O

O

60

40

20
temperature of 1 lb (0.45 kg) of water 1oF

(0.56oC). A metric equivalent of the Btu is

the kilojoule (kj) or 1 Btu = 1.005 kj.

A truck refrigeration system must have sufficient capacity to remove heat generated by

the sources described below.

Residual heat from the air inside the trailer,

and heat in the insulation and inner lining of

the trailer.

Exterior heat conducted through the floor,

walls, and ceiling. It is dependent on the

temperature differential between the inside

and outside air, type and thickness of insulation, and the area of the conducting surfaces.

Solar radiation will increase the temperature

of outside surfaces where the trailer body is

exposed to the sun. 

Infiltration heat from warm outside air

through small holes, cracks, and door seals.

It increases refrigeration requirements. 

Excess heat in the commodity above the

desired transit temperature.

Heat of respiration generated by all fresh

fruits and vegetables. Some products, such

as asparagus, corn, and strawberries, respire

at a higher rate than other products, such as

apples, oranges, and potatoes. The rate at

which respiration heat is generated also

varies with the temperature of the product. It

is considerably less at temperatures near

freezing than at normal harvest temperatures. Table I-1 in appendix I gives the

amount of heat produced by various fruits

and vegetables at given temperatures.

Refrigeration Methods

In the past, several methods of refrigerating

trucks have been used. These include ice, ice

and salt, dry ice, hold-over plate systems,

cryogenic systems, and mechanical refrigeration. Today, however, mechanical refrigeration is the predominant type. Trailers refrigerated with cryogenic refrigerants, usually

liquid carbon dioxide (CO2) or nitrogen

(N2), have been used to some extent over the

past three decades, but they are not as popular as trailers refrigerated mechanically.

Mechanical Refrigeration

Mechanical refrigeration operates by absorbing heat at one point and dispensing it at

another. This is accomplished by circulating

a refrigerant between two points. The refrigerant picks up heat through a coil (evaporator) inside the cargo space and discharges it

through another coil (condenser) on the outside. The refrigerant is circulated through

the system by a compressor, which is driven

by a gasoline, diesel, or electrical motor.

On highway trailers most mechanical refrigeration units are “nosemounted,” with the

engine, condenser, and other accessories on

the outside front of the trailer, and the evaporator coil and air fans directly inside.

Refrigerated containers built for intermodal

service have the compressor engine and condenser coil recessed flush with the outside

surfaces in the front section of the containers. This allows the containers to be evenly

stacked aboard rail cars or containerships.

Mechanical refrigeration units are rated

according to their ability to remove or produce heat. The cooling capacity of a unit is

expressed in the number of Btu’s per hour a

unit can remove at 100oF (38oC) outside and

at 35oF (1.7oC), 0oF (–18oC), and –20oF

(–29oC) inside trailer temperature. Heating

capacity of the unit is measured in Btu’s per

hour, while inside trailer temperatures are

65oF (18oC) or 35oF (1oC) under 0oF

(–18oC) ambient. (The rating procedure is

based on the Air-Conditioning and Refrigeration Institute’s (ARI) Standard 1110.) The

refrigeration capacity needed for a particular

load depends on the desired product temperature, the amount of vehicle insulation,

ambient temperatures, product temperature at

loading, amount of product respiration heat,

and the extra capacity (reserve) desired.

Today’s refrigeration units are equipped with

microprocessors programmed to control the

operation of the unit so that both refrigeration

and fuel efficiency are maximized. Air temperatures are monitored at the discharge and

return locations, and adjusted to demand for

refrigeration at the thermostat set-point. This

reduces temperature spread around the thermostat set-point, which reduces dehydration

2
3

and maintains product quality. The microprocessors also can be programmed to provide

diagnostic tests and automatically run through

a pretripping mode. Some of the microprocessors are radio-equipped and may be contacted

via satellite to monitor performance of the

refrigeration unit, pinpoint geographic location of the trailer, monitor product temperatures, and perform other functions.

Ice

Ice is a good absorber of heat (table 1) and

also helps to maintain humidity in loads of

fresh produce. The main drawbacks for ice

are its weight, which cuts down on the payload; the difficulty and expense of replenishing ice enroute; the need for water-resistant

packaging when applied as top-ice; and the

damage some fresh fruit and vegetables

incur when contacted by ice.

Crushed or slush-ice blown over the top of

produce loads is used to refrigerate and maintain high levels of humidity for certain products. This is known as “top-icing.” Some

shippers may apply the crushed ice or slushice to individual pallet loads or in individual

boxes of product (package-ice) before loading. 

Cryogenic Refrigerants

Cryogenic (low-temperature) refrigerating

systems, which use liquid or solid carbon

dioxide (CO2) or liquid nitrogen (N2), are

available for highway trailers. They are used

primarily in delivery operations requiring 

1-day or less transit time, since supplies of

liquid cryogens are not available at truck

stops. Advantages of the cryogenic systems

are that they have fewer moving parts to

maintain and replace, and also allow quick

recovery of thermostat set-point temperature

after delivery stops.

Liquid cryogenic systems usually operate by

having the liquid refrigerant in pressurized

tanks. A temperature-sensing element inside

the trailer activates a controller which

releases the liquid refrigerant through a

spray nozzle at the ceiling of the trailer. The

liquid CO2 or N2 spray flashes into gas as it

hits the warmer air in the trailer, absorbing

the heat. When the desired temperature is

reached, the sensing element sends a signal

to the controller to shut off the flow of

refrigerant. In another type system, the liquid CO2 is circulated through a coil or plate

heat exchanger and the vaporized gas vented

outside. A third type of system stores CO2

snow in a full length ceiling bunker and

cools as the snow melts. 

WARNING: Allow adequate time for

replenishment of oxygen before entering a

vehicle refrigerated by CO2 or N2. Workers

Table 1. Heat Absorption Characteristics of Various Refrigeration Mediums

Amount of Heat Absorbed 

At or

Medium Above Freezing1 Below Freezing

Btu’s/lb Btu’s/lb

Ice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

Carbon Dioxide (CO2)

Liquid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 120

Solid (dry ice) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240

Nitrogen (N2)

Liquid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 165

1 Freezing = 32oF (0oC)
4

entering a vehicle with concentrations of

CO2 or N2 gases may be rendered unconscious by the lack of oxygen. 

Also, high concentrations of cryogenic

refrigerant gases (generally above 20 percent) may have an adverse effect on fresh

produce. Most fresh fruits and vegetables

will eventually suffocate in a 100-percent N2

atmosphere, although many products will

tolerate high levels of N2 for a few days

without injury. High percentages of CO2 gas

in the atmosphere may cause off-flavors,

off-colors, and physiological disorders in

fresh produce. On the other hand, moderate

concentrations of this gas are successfully

used to retard decay and ripening of fruits

and vegetables during transit and storage.

Generally, N2 atmospheres are not harmful

to food products, and CO2 atmospheres help

retard microbial growth on fresh meat and

meat products (see “Controlled and Modified Atmospheres”). Neither CO2 nor N2 gas

will harm frozen foods.

Solid CO2 (dry ice) may be in the form of

blocks, snow, or pellets, all of which are

used as refrigeration mediums in transport

vehicles. The most frequent use of solid CO2

is in frozen food and ice cream delivery

trucks. Solid CO2 may be used as an emergency refrigerant in the event of mechanical

unit breakdown in vehicles hauling frozen

products. Dry ice changes into gas at

–109oF (–78.3oC). Table 1 gives the heat

absorption characteristics of these mediums.

Trailer Design and Construction

Insulation

Vehicles used to transport perishable food

products should be well insulated to retard

the flow of heat through their walls. Insulating quality is measurable, and the industry

standard is the U factor (coefficient of heat

transfer through a trailer body). The lower

the U factor, the better the insulation.

Plastic foams are the predominant material

used in insulating refrigerated vehicles because

they offer a low U factor, are lightweight,

waterproof, and noncorrosive. Additional insulation advantages are obtained when the plastic

is “foamed in place” during manufacture. This

procedure fills in cracks and crevices that

would otherwise allow air leakage.

Insulation quality is further enhanced by the

use of highly polished steel or aluminum

exterior skin which reflects heat rays from

the sun or road surfaces. There also are

reflective paints for refrigerated vehicles.

The reflecting effect of any material is

diminished, however, if the outside of the

vehicle is not kept clean. 

High-quality insulation will be of little value

if door seals are leaking. Door seals must be

properly fitted and in good repair.

Air Circulation Systems

Air circulation is one of the most important

factors in protecting refrigerated loads of

perishable foods. Refrigeration capabilities

are meaningless if the refrigerated air is not

properly circulated to maintain product

temperature.

Air circulation carries product heat and the

heat which penetrates the walls, floors, and

ceiling of the trailer to the refrigeration unit

where it can be removed. Heated air may be

circulated to keep fresh produce from incurring chilling or freezing injury. Air circulation also is important to ensure uniform temperatures throughout the load.

There are two major methods of circulating

air in refrigerated vehicles. Overhead, or

top-air, delivery is the conventional method.

The second method is bottom-air delivery,

which has been employed extensively in

seagoing van containers for several decades,

but only to a limited extent in highway trailers. Figures 2 and 3 illustrate the pathways

of airflow in top- and bottom-air delivery

trailers respectively.

Top-air delivery 

In trailers with top-air delivery, air circulation and subsequent control of load temperatures are enhanced by the construction features below.

Ceiling ducts to direct the air from the

blower to the rear of the trailer. The Nation-
al Perishable Logistics Association/ Refrigerated Transportation Foundation

(NPLA/RTF), a non-profit association of

refrigeration equipment manufacturers and

users, recommends that the air delivery

chute provide a minimum of 240 square

inches (1548 cm2) of cross-sectional area

from the front of the vehicle to 10 to 15 feet

(3 to 5 m) from the rear. Progressive air spill

provisions should be provided (except in the

front 10 feet 

(3 m) of length. A maximum load height line

should be painted on the walls below the

level of the bottom of the air delivery chute.

Figure 4 illustrates features considered critical for maintaining the airflow pathways in

a loaded refrigerated trailer. 

Vertical channels or ribs on the inside of

the rear doors and provisions for cross bracing at the rear of the load to prevent the

blocking of air circulation between the load

and the rear doors in the event of load shift. 

High airflow floors that allow air to circulate under the load. About 240 square inches

(1,548 cm2) of return air passage are needed

for the average trailer’s refrigeration fan to

operate at 100 percent capacity. Figure 5

shows the effect of different floor configurations on return air space. The product should

be loaded on pallets or floor racks when

space for air circulation under the load is

inadequate due to floor design. 

Figure 2. 

Pathways of air in a

trailer with a top-air

delivery system. 

CONDENSER

HEADER

STACK

BULKHEAD WALL

RETURN AIR

FAN

DISCHARGE AIR EVAPORATOR

Figure 3. 

Pathways of air in a

trailer with a bottom-air

delivery system.

CONDENSER

T–RAIL FLOOR

FLOOR COVER

IN OPEN SPACE

DISCHARGE

FAN

EVAPORATOR RETURN

5
6

Ribbed sidewalls or spacers at least 1 inch

thick (3 cm) to allow top airflow down the

sides of the load. This reduces the amount of

heat conducted across the walls to or from

the product. Up to 20 percent of the top airflow should bleed off down the sidewalls. 

A solid-front bulkhead designed to allow air

free return to the refrigeration unit. If the air

is blocked, the fan will turn, but not blow

air. The NPLA/RTF recommends that the

bulkhead be positioned a minimum of 3

inches (8 cm) from the front wall. A minimum of 6 inches (15 cm) of open space

should be left between the bottom of the

floor and the bottom edge of the bulkhead.

The top side of the bulkhead should have 30

to 50 square inches (196 to 323 cm2) of

open area to allow mixing of top and bottom

air, and to allow some return air to the thermostat should the airflow be interrupted by

improper loading or load shift. Bumpers or

vertical strips should be attached to the open

area at the bottom of the bulkhead wall to

prevent the load from blocking air return to

the blower under the bulkhead. 

Bottom-air delivery

A few refrigerated highway trailers and

most van containers used in overseas trade

are equipped with bottom-air type delivery.

In this type system, air is forced under and

up through the load at a rate of 3,000 to

5,000 cubic feet per minute (85 to 142

cubic meters per second) and a static pressure of 1.5 to 3 inches (0.37 to 0.73 kPa)

water. (The abbreviation kPa stands for

kilopascal, a metric unit used to measure

pressure.) The air returns to the refrigeration unit over the top of the load and

through the top of the bulkhead (figure 3). 

Multi-temperature Vehicles

Within the last decade there has been a rapid

growth in the use of multi-temperature trailers for food delivery operations, especially

Figure 4. 

Features essential for

maintaining the critical

airflow chain in trailers

with top-air delivery.

ADEQUATE

HEAD SPACE

WALL CHANNELS

RETURN AIR

BULKHEAD

DEEP FLOOR CHANNELS

REAR

DOOR

CHANNELS

AIR CHUTE
7

for fast food and independent grocery stores.

Multi-temperature vehicles usually have

three compartments separately controlled at

0oF (–18oC) or below for frozen foods,

around 35oF (2oC) for chilled foods, and

around 55oF (13oC) for chill-sensitive products (figure 6).

Liquid CO2 refrigeration systems are used in

some delivery operations. A major advantage of these systems is fast temperature

recovery after door openings. This is particularly important for protecting the quality of

frozen foods in warm weather where cumulative door opening time may be one or

more hours. The injection of liquid CO2 into

the compartments after a door opening provides almost instantaneous recovery to the

thermostat set-point.

Mechanically refrigerated vehicles have a

separate coil in each compartment. Each coil

operates from a single refrigeration unit at

an independent temperature set-point .

Humidity

The proper humidity or moisture content of

the air surrounding fresh fruit and vegetables helps maintain quality during transport.

Most perishable horticultural products

require high relative humidities of 85 to 95

percent to prevent dehydration and to keep

them fresh and crisp.

Relative humidity, as used in this text, is the

percentage of water vapor in the air in relation to the saturation point of the air at a

given temperature.

In mechanically refrigerated vehicles, moisture is continually evaporated from the product and condensed from the circulating air

by the refrigeration coil. Some product

moisture loss during transit must be accepted, but it can be minimized by the following

practices:

• using top- or package-ice where possible;

• precooling thoroughly to reduce the temperature differential between the product

and the surrounding air;

• keeping the refrigeration coil only a few

degrees colder than the desired transit

temperature;

Figure 5. 

Effect of different floor

configurations on returnair space under the load.

T–RAIL FLOOR

198 SQ. INCHES

325 Sq. Inches

45 Sq. Inches

1 1/4"

3 1/2"

1 1/4"

2 1/4"

DUCT BOARD FLOOR

& PALLET

DUCT BOARD FLOOR
8

• waxing the product or using semi-permeable wraps to reduce evaporation; and

• installing a humidity control system.

Precooling the Product

To maintain a fresh appearance, prevent

decay, and extend the market life of most

fresh fruits and vegetables, it is necessary to

start lowering the temperature and removing

the field heat from the product as soon after

harvest as possible. Any cooling completed

before the product is shipped is referred to

by the industry as precooling. Precooling

may include one or a combination of the following methods:

• refrigerated forced air;

• vacuum cooling; 

• hydrocooling; and

• slush- or package-ice.

Some fresh fruits, vegetables, and carcass

meats are shipped before they have been precooled to the proper transit temperature. The

ideal situation would be for the carrier to

accept only properly precooled product. When

this is not practical, the trailer’s refrigeration

system must bear the additional heat load. 

Most truck refrigeration units have enough

reserve capacity to remove a reasonable

amount of heat in addition to respiration heat

and heat transferring through the vehicle

Figure 6. 

A typical multi-temperature

mechanically refrigerated

trailer.

Photo courtesy of Carrier-Transi-
9

body. However, if the product is much above

the desired transit temperature at loading

time, the entire heat load should be estimated

(see appendix I). If the estimated heat load is

more than the refrigeration unit is rated to

bear, the trailer should not be used.

Freezing and Chilling Injury

Trucks transporting perishables through

areas with outside temperatures much lower

than 32oF (0oC) may need to be warmed

rather than refrigerated to prevent freezing

or chilling injury. Product freezing also may

occur if the thermostat setting is too low,

particularly on the top layer where air exits

the refrigeration unit discharge chute.

Freezing fresh meat will darken its color and

increase thaw drip. Eggs may crack and

incur irreversible physical changes by freezing. The texture of some cheeses are

changed by freezing. 

Freezing losses are most common in fruits

and vegetables such as apples, celery, and

lettuce which normally move at temperatures near their freezing point. The extent of

injury varies with the characteristics of the

product and the severity of freezing. Commodities such as beets and cabbage can

withstand light freezing and thawing several

times without permanent injury. Other products such as potatoes and tomatoes are permanently injured by only one slight freezing. Table 2 groups certain commodities by

their sensitivity to freezing injury.

Some fresh fruits and vegetables are subject

to low temperature or chilling injury at temperatures above 32oF (0oC). Symptoms may

be pitting, discoloration, off-flavors, physiological deterioration, and increased decay.

Chilling injury varies with both time and

temperature. Some commodities, such as

bananas, will be injured by a few hours’

Table 2. Sensitivity of Some Fruits and Vegetables to Freezing

Most sensitive1 Moderately sensitive2 Least sensitive3

Apricots Apples Beets

Asparagus Broccoli, sprouting Brussels sprouts

Avocados Cabbage, new Cabbage, old

Bananas Carrots Dates

Beans, snap Cauliflower Kale

Berries4 Celery Kohlrabi

Cucumbers Cranberries Parsnips

Eggplants Grapefruit Rutabagas

Lemons Grapes Salsify

Lettuce Onions, dry Turnips

Limes Oranges

Okra Parsley

Peaches Pears

Peppers, sweet Peas

Plums Radishes

Potatoes Spinach

Squash, summer Squash, winter

Sweet potatoes

Tomatoes

1 Commodities likely to suffer injury by one light freezing.

2 Commodities able to recover from one or two light freezings.

3 Commodities that can be lightly frozen several times without sustaining serious damage. 

4 Except cranberries.
10

exposure to chilling temperatures. Others

can be held below the desired storage temperature for several days before incurring

serious injury. Table 3 lists some of the

major fresh produce susceptible to chilling

injury when held below recommended temperatures during transit or storage.

Table 3. Some Fruits and Vegetables Subject to Chilling Injury at Abovefreezing Temperatures

Approximate lowest 

Commodity safe temperature1

oF oC 

Avocados:

Cold-tolerant varieties . . . . . . . . . . . . . . . . . . . . . . . . . 40 4.4

Cold-intolerant varieties

(West Indies) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 12.8

Bananas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 12.8

Beans (snap) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.2

Cucumbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.2

Eggplants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.2

Grapefruit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 10.0

Lemons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 10.0

Limes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 7.5

Mangoes:

Irwin and Zill varieties . . . . . . . . . . . . . . . . . . . . . . . . . 50 10.0

Haden and Keitt varieties . . . . . . . . . . . . . . . . . . . . . . . 55 12.8

Melons:

Cantaloupes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 2.2

Honeydew, Casaba, Crenshaw,

and Persian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.2

Watermelons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 4.4

Okra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.2

Oranges (California and Arizona

grown) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.3

Papayas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.2

Peppers (sweet) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.2

Pineapples:

Mature-green . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 10.0

Ripe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.2

Potatoes:

Table stock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.3

Chipping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 10.0

Pumpkins and hardshell squashes . . . . . . . . . . . . . . . . . . 50 10.0

Sweet potatoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 12.8

Tomatoes:

Mature-green . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 12.8

Pink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.2

1 Based on maximum transit time of 5 days; however, chilling injury may vary considerably by cultivar, harvest season, holding time, maturity of commodity, etc.
11

Since heat moves toward the cold source,

during very cold weather the heat from

product loaded against the walls and floor in

a truck will move outward. The best methods of preventing this heat loss and subsequent freezing or chilling damage are: 

• reducing the amount of surface contact of

the product with the floor and walls; and

• circulating warmed interior air around the

perimeter of the load.

Various loading methods may be used to

reduce product contact with the walls and

floor. For example, the offset-by-layers loading pattern reduces box contact with the walls

by about 50 percent and also provides ducts

for warm air to circulate along the length of

the wall (figure 7a). Hand-stacked loads of

bagged products can be pyramid stacked (figure 7b). Palletized loads should be centerloaded away from the walls (figure 7c). 

Enhance perimeter air circulation by using

high airflow or deep T-rail floors (figure 5).

If the vehicle is not equipped with deepchanneled floors, use pallets or disposable

wooden floor racks to prevent contact of the

product and floor and for more space for the

warmed air to circulate under the load.

Ribbed or vertically grooved walls will allow

increased air circulation down the walls and

reduce surface contact with the product. 

Controlled and Modified 

Atmospheres

The practice of using controlled or modified

atmospheres as a supplement to refrigeration

is increasing. Such atmospheres are

achieved by altering the normal atmosphere

in the vehicle with varying concentrations of

one or more gases, usually oxygen (O2), carbon dioxide (CO2), and nitrogen (N2).

A controlled atmosphere (CA) is attained

when concentrations of gases making up the

atmosphere in a vehicle are constantly replenished to maintain predetermined levels. In

modified atmospheres (MA), gas concentrations are initially modified to meet specific

product criteria, but not consistently replenished in transit to maintain the initial levels.

Nearly every product, and sometimes each

variety, has a different combination of gases

in which it keeps best during storage. An

atmosphere that improves the keeping qualities of one product may have an adverse

effect on another. Temperature and humidity

modify the effects of controlled atmospheres.

For these reasons, consult appendix II of this

handbook and information on individual

commodities in the USDA Handbook No. 66

(see Selected Bibliography) before applying

a modified atmosphere to a product load. 

Strawberries are the product most commonly shipped in a modified atmosphere. CO2

gas is a basic component in atmospheres for

berry and cherry shipments because it is a

mold retardant. N2 gas usually is a basic

component for green leafy produce since

CO2 gas may cause discoloration of these

products. Reducing O2 levels retards ripening and decay that take place in normal air.

Extremely high or disproportionate levels of

any gas may result in product discoloration

and off-flavors. 

Sealing the trailer tightly enough to hold the

desired concentrations of gases during transit is a major problem in truck shipments. A

more common practice is to load the trailer,

apply a plastic film curtain sealed around

the inside of the rear doorway, evacuate the

air through port valves, and then inject the

desired atmosphere. In some cases, a large

plastic bag enclosing the entire cargo space

is inserted in the trailer, the product is

loaded inside the bag, the bag is sealed and

the desired atmosphere is injected. For transit periods of more than several days, vehicles containing a modified atmosphere

should be recharged with gas enroute.

For both truckload and less than truckload

lots, individual pallet loads of the product

are sealed in plastic bags, the air evacuated,

and a modified atmosphere injected. The

preparation of vehicles or pallet loads for

MA shipments is usually done by companies

specializing in this trade. They also market

the applicable gases, usually under a registered trademark. In some cases they provide

services for monitoring and recharging the

atmospheres in transit.
12

Figure 7.

Methods of loading to

reduce contact of

products with walls and

to reduce the chance of

freezing or chilling injury

in extremely cold

weather: (a) crosswiseoffset stacking of boxes

or crates, (b) pyramid

stacking of bagged

products, and (c) centerloading of palletized

loads.

(A) CROSSWISE - OFFSET STACK (B) PYRAMID STACK

(C) CENTER - LOADED
13

Preparation for loading is an important step in

putting together a successful shipment. When

developing and implementing a good preloading plan, consider the following factors: 

Adequacy of Equipment

The truck’s refrigeration system should be

operating properly and have the capacity to

maintain the proper temperature of the

intended product load. If the vehicle is

NPLA/RTF certified, the refrigeration unit

and insulation rating can be found on performance plates or decals attached at various

locations (see figure 8). These decals also

provide information on optional equipment

on the trailer which affects refrigeration performance, such as bulkheads, air chutes, etc.

Cleaning and Sanitation

Clean and sanitize the vehicle. Cleanliness

prevents bacterial, chemical, and odor contamination of food product loads. Remove all

loose debris and wash or sweep the floors

clean. The floor drains and grooves should

be free of debris so drainage will not be

blocked.

Certain cleaning procedures may be required

by law in cases where a meat product may

become contaminated by direct or indirect

contact with the interior surfaces of the

vehicle. Also, certain cleaning laws may

apply due to previously hauled cargo, such

as chemical residues or municipal wastes.

(See also section VI, “Regulatory Considerations for Truck Construction Materials,

Cleaning Compounds, and Sanitation.”)

Fatty or oily food products, such as butter,

oleomargarine, and meats, are highly susceptible to contamination by strong odors.

Fresh fruit, such as apples and bananas, also

easily absorb strong odors. Thorough cleaning and airing of vehicles previously used

for hauling fish, cabbage, and other odorous

products are necessary. Leaving freshly

opened cans of ground coffee for 8 or more

hours in a closed vehicle may be helpful in

absorbing odors. The grounds may be spread

over the floor and then swept clean before

loading. Truckers should refrain from transporting products leaving strong residual

odors if they plan to haul fresh meats or

other odor-absorbing products soon after. 

Vehicle Maintenance

Properly maintain vehicles. A regular maintenance program that keeps a refrigerated

truck in good repair improves its ability to

maintain desired product temperatures during transit. In the long run, maintenance and

repairs are less costly than claims and lost

revenue from delivery of products in poor

condition.

Rough or splintered sidewalls and protruding nails or screws can tear containers and

damage the commodity. Cracked wall liners

provide lodging points for dirt and old food

particles which encourage microbial and

insect infestation. Walls punctured by forklifts or broken at the seams allow moisture

to penetrate the insulation and reduce its

effectiveness. 

Check door seals and floor drain caps regularly and repair or replace as needed. The

mashed-end rubber caps on floor drains tend

to clog with debris, and wash crews sometimes cut them off. All seals should be maintained. Dirt and air are sucked into open

spaces left by worn and missing seals and

drain caps. This adds to refrigeration loads

and product contamination.

Keep air chutes or ducts in place and free of

holes. The ducts are designed to distribute

air so that the load is uniformly cooled.

Defective or missing ducts will result in air

II. Preparation for Loading
Figure 8. 

Location of NPLA/RTF 

certification plates and 

decals which provide 

information on refrigeration 

rating and optional equipment 

on refrigerated trailers at 

time of manufacture.

14

(TEMPERATURE CONTROL UNIT MANUFACTURER’S NAME)

TEMPERATURE CONTROL UNIT PERFORMANCE

Cooling Heating Air Discharge

(100oF) Ambient (0oF Ambient)

35oF___Btu/hr 65oF___Btu/hr No Load____CFM

0oF___Btu/hr 35oF___Btu/hr System Load____CFM

–20oF___Btu/hr

MODEL ______________________

Tested in accordance with the Refrigerated Transportation

Foundation.

Recommended Practice No. ___________. (latest revision)

2 HEAT TRANSFER

CHARACTERISTICS

(VEHICLE MANUFACTURER’S NAME)

THERMAL PERFORMANCE

This structure is certified in accordance with Truck Trailer

Manufactuers Association Recommended Practice No. 38 –

(latest revision) and Refrigerated Transportation Foundation

Method for Classification, Recommended Practice

No.________________________________(latest revision)

V.I.N. __________________________________________

Date of Certification _______________________________

Heat Transmission Rate __________________BTU/hr –oF

Floor Airflow Area ______________________________in2

Side Lining Airflow Area ________________________in2/ft

of vehicle length

Rear Door Airflow Area __________________________in2

1 REFRIGERATION CAPACITY

3 COMBINED

EQUIPMENT

IDENTIFICATION
REFRIGERATED TRANSPORTATION FOUNDATION

EQUIPMENT CLASSIFIED

BY: _______________________________________

DATE OF CLASSIFICATION:___________________

TRAILER V.I.N.: _____________________________

TEMPERATURE CONTROL

UNIT MODEL NUMBER: ______________________

Vehicle Bulkhead Chute Floor Door Side

Rating Lining Lining

15

VEHICLE

SPECIFICATIONS CODE

Bulkhead

Solid (pressure) S

Lattice L

None N

Air Delivery System

Yes Y

None N

Floor

High H

Medium M

Low L

Flat F

Rear Doors

High H

Medium M

Low L

Flat F

Sidewalls

Non-flat (Ribbed) R

Flat F

QUALITY PRODUCT PROTECTION

Vehicle Ratings Type of Product Protection

C65 = 65F Controlled Temperature

C35 = 35F Fresh Fruit and Vegetables

F = 0F Frozen Foods

DF = –20F Ice Cream & Frozen Foods

▲

▲
16

short-circuiting back to the refrigeration unit

over the top of the load. This often causes

freezing on the top layer and hot spots in the

lower layers.

Precooling or Prewarming 

of the Vehicle

Precool or prewarm the vehicle to the

desired transit temperature for the intended

product load. During hot weather, precooling reduces the chance of overloading the

refrigeration system. It also prevents further

warming or thawing of the product from

heat in the walls and floor. A number of

variables, such as ambient temperatures,

refrigeration unit capacities, and insulation,

make it hard to have a set procedure for precooling. A recommended procedure is to set

the thermostat at the desired temperature,

close the doors of the vehicle, and run the

refrigeration unit until the heat transfer

through the vehicle body is stabilized at the

thermostat set-point. This may take 2 or

more hours in hot summer weather. Some of

the newer refrigeration units are equipped

with micro-processors with an automatic

precooling cycle function. Still, schedule

adequate time for precooling.

CAUTION: Shut the refrigeration unit off

when loading from an open dock. Leaving

the doors open may result in ice forming on

the refrigeration coil, blocking refrigerated

air circulation during transport.

During extreme subfreezing weather, prewarm the interior of the vehicle before loading commodities such as fresh onions or

potatoes. Most vehicles are equipped with a

heating cycle on the refrigeration unit. Operate the unit on the heat cycle far enough in

advance of loading to stabilize the interior

air and body temperature of the trailer at the

desired transit temperature of the product. 

Preloading Checklist

The following is a suggested preloading

checklist: 

( ) Refrigeration unit operating properly?

( ) Thermostat calibrated?

( ) Refrigeration air chutes or ducts properly

installed and in good repair?

( ) Door seals in good condition?

( ) Doors seal tightly when closed?

( ) Walls free of cracks or holes?

( ) Front bulkhead installed?

( ) Floor drains open?

( ) Inside of the vehicle clean and odor free?

( ) Floor grooves free of debris?

( ) Inside length, height, and width adequate

for the load?

( ) Load locks or other devices available to

secure load?

( ) Is the trailer or container precooled or

prewarmed?
17

The packaging, handling, and trailer equipment for perishable foods varies considerably, and this complicates loading decisions

for truck drivers. Consider the following

factors, along with the kind of equipment

available, when planning a load. 

Type of Air Delivery

Currently there two types of air delivery 

systems available on refrigerated trailers and

containers. Each system requires different

loading procedures for both hand-stacked

and palletized loads to maximize cooling

efficiency and maintain temperature control.

Top-air delivery is the conventional system

used in refrigerated trailers (see figure 2).

With this system, high velocity, but low

pressure, air exits the refrigeration unit at

the front ceiling, travels over the top of the

load, down between the end of the load and

rear doors, and under and through the load

to return to the refrigeration unit at the

front of the vehicle. When loading a top-air

vehicle, keep pathways open for airflow

back to the refrigeration unit. For respiring

produce, air pathways also are needed

through the load interior for removal of

respiration heat. 

Bottom-air delivery systems are used mainly

on intermodal van containers for export

shipments. In bottom-air systems, refrigerated air is forced down the front bulkhead and

under the load through a T-rail floor, and

then vertically up through the load (see figure 3). A high static pressure is maintained

under the load to assure a low velocity but

steady movement of air through small openings in the load. Load a bottom-air vehicle

tightly over the floor area, and cover any

open space on the floor not covered by the

load to maintain the air pressure under the

load. 

Type of Shipping Container

Load shipping containers in a manner that

takes maximum advantage of their inherent

strength. Different containers are stacked

and handled in varying ways because of

their design, the way they are packed, and

the material from which they are made.

Most containers are designed to withstand

more pressure or weight on one side or area

without collapse or damage to the contents.

Certain types of “packs” tend to leave a

bulge on one or more faces of the container.

If at all possible, do not load bulged containers with pressure on the bulging faces.

Wooden wirebound crates used for corn are

an example of this type pack. Load these

containers on their sides to prevent crushing

of the contents under the bulge.

Wooden boxes, lugs, and wirebound crates

are designed to bear weight on the ends

only. The tops, bottoms, and sides usually

are made up of thin slats which serve only

to keep the product within the container.

Stack these containers directly on each other

so that the overhead weight is borne by the

ends of the crate, or the contents may be

severely crushed and bruised. 

Corrugated fiberboard boxes are designed to

bear vertical overhead weight on their four

walls. Load fiberboard boxes upright on

their bottoms and stack evenly on top of

each other. The four corners are the strongest points. Avoid cross-stacking where

excessive pressure put on the boxes at midsection may cause product damage. Boxes

may usually be cross-stacked on the top

layer. 

Wooden baskets and hampers are designed

to withstand overhead weight bearing vertically on their tops or bottoms. Fasten the

cover lids securely at all fastening points so

that the lid bows slightly. The bow distribIII. Loading Considerations
18

utes overhead weight evenly to the sides of

the basket rather than letting it bear directly

on the produce under the cover.

Bulk and bagged commodities are highly

susceptible to bruising from overhead

weight, especially when loaded on grooved

or rough floors. Commercial cushioning

materials, such as paper and plastic foam

pads, will provide some protection for these

products. Fiberboard slipsheets also may be

used for floor cushioning. Any cushioning

material should be perforated for air circulation. Do not use materials, such as straw,

that will block air circulation under the load. 

During cold weather, floor cushioning material also serves as insulation to prevent

freezing damage at the point it is most likely

to occur. However, the most effective

method of preventing freezing of the product at floor level is to circulate warmed air

under the load. In vehicles not equipped

with high airflow floors, raise the load on

pallets or floor racks to get adequate air circulation under the load.

Whether Frozen or Nonfrozen

Load frozen foods that have been cooled to

the desired 0oF (–18oC) or below transit

temperature in a different manner from fresh

respiring produce. Load boxes of frozen

food tightly together with as little contact

with the vehicle floor and walls as possible.

The goal is to have cold air circulating

around the load perimeter to intercept heat

radiating through the body of the trailer

before it reaches the frozen cargo. (See also

the section “Frozen Foods.”)

Bracing Needs

Bracing prevents the load from shifting and

blocking air circulation channels and/or

causing physical damage to the product. It is

especially important to secure containers in

the top layers toward the rear of the load.

Here they are highly susceptible to bouncing

and toppling, and subsequent bruise and

abrasion damage from shock and vibration

transmitted from the road bed. 

Prevent the accumulation of lengthwise

slack space during loading. Use cross-bracing at the end of the last stack to prevent the

cargo from shifting backward and blocking

air circulation at the rear doors. This is particularly important in loads for piggyback

rail (TOFC) shipments, where the vehicles

may be loaded so they are moving backwards. If the load is a split shipment or a

multiple drop-off (one that is consigned to

several receivers), use cross-bracing at the

end of the last stack left after each drop-off

to keep the cargo in place until the next stop

is reached. Use air bags, spacer blocks, and

load lock bars to secure palletized loads.

Compatibility of Mixed Loads

Many truck shipments contain two or more

different food products. Consider five

important factors in determining the compatibility of products in mixed loads: 

(1) required commodity temperature, 

(2) required relative humidity, 

(3) emission of physiologically active gases

such as ethylene, 

(4) odor-absorbing characteristics, and 

(5) modified atmosphere requirements. 

The desired transit temperature of products

shipped together should be within reasonably close range. For example, mature green

tomatoes requiring a transit temperature of

55oF (13oC) should not be shipped in combination with lettuce needing a transit temperature of 32oF (0oC). 

The relative humidity requirements of mixed

products should be reasonably close. Some

products may be shipped in contact with ice

and saturated by melt water. Other products

may be injured by contact with ice or water

saturation.

Certain fruits and vegetables produce ethylene gas during respiration. Ethylene may

bring about premature ripening or it may

damage carrots, lettuce, most flowers, and

some nursery stock. Fruits and vegetables
19

producing significant quantities of ethylene

are apples, avocados, bananas, cantaloupes,

honeydew melons, peaches, pears, plums,

and tomatoes. Commodities that should

retain a green color during transit, such as

bananas, cucumbers, and peppers, should

not be shipped in combination with heavy

ethylene producers. Ethylene production is

less pronounced at temperatures near freezing than at higher temperatures. Exchanging

the air in the vehicle periodically by opening

vent doors will help reduce ethylene

buildup. Ethylene scrubbers also are available commercially.

Take care not to mix shipments of odor-producing products with odor absorbers. Odors

given off by apples, citrus, onions, pineapples, and fish are readily absorbed by dairy

products, eggs, meats, and nuts. Some products, such as apples, are capable of both giving off and receiving odors. Loading combinations to avoid are apples or pears with

celery, cabbage, carrots, potatoes, or onions;

celery with onions or carrots; and citrus fruits

with any of the strongly scented vegetables.

Apples and pears may acquire an earthy taste

and odor if shipped with potatoes. 

Use the “Load Compatibility Groups” section in appendix II for determining the loading compatibility of various products. 

Whether Palletized or Unitized

Depending on the commodity and area of

production, anywhere from 75 to 90 percent

of the fresh fruit and vegetable shipments

are now unitized on pallets or slipsheets.

Unitized shipments offer the advantages of

reduced labor and less manual handling of

the product, but have unique loading

requirements for protecting food products

during transit. (See also the section “Loading Methods.”)

Length of Transit Period

The length of time a product will be in transit will affect loading decisions. For example, a denser loading pattern can be used in

an overnight shipment compared to one that

takes several days in summer heat. In overseas shipments where transit periods may be

2 weeks or longer, it is imperative that all of

the recommended transit requirements for

the individual commodity be met to assure

maximum shelf life.
20

Basic Terminology

Figure 9 is a dimensional view of a load in a

truck trailer showing arrangement of containers in rows, stacks, and layers. A row is

a line of containers extending the length of

the trailer, one container in width, and as

high as the load itself. A layer is a course or

stratum of containers, one container high,

usually extending the length and width of

the trailer. A stack is a line of containers

extending from one side wall to the other

and from the top to the bottom of the load,

parallel to the front and rear end of the vehicle, and one container in length.

Loading Vehicles 

with Top-air Delivery

Hand-stacked Loads

When hand-stacking respiring product in

trailers with top-air delivery, use an airflow

pattern. The goal in airflow patterns is to

build air channels through and around the

load to maximize the circulation of refrigerated air for interception of heat penetrating

the trailer body and removal of heat from the

product. Figures 10a, b, and c illustrate a

typical airflow pattern with horizontal air

channels constructed between rows in alternate layers. This pattern may be modified in

a number of ways to accommodate varying

IV. Loading and Load Patterns

Figure 9. 

Dimensional view of a

load in a truck semitrailer showing arrangements of containers in

rows, stacks, and layers.

LAYER

LAYER

4TH

3RD

2ND

1ST

STAC
21

vehicle and container sizes (figure 11).

To maximize cooling of hand-stacked loads

in vehicles with top-air delivery: 

• use an airflow loading pattern for respiring

products (figure 10);

• build a header or starter stack against the

front bulkhead with vertical channels to

facilitate air flow from the horizontal load

channels back to the refrigeration unit 

(figures 10a and b); (After the starter

stack, all other stacks in the load must be

exactly the same, or the horizontal channels will be blocked.) 

• load top boxes in a solid layer to prevent

Figure 10. 

A typical airflow loading

pattern for commodities

packed in fiberboard

boxes: (a) longitudinal

view, (b) header stack,

and (c) rear view of all

other stacks.

(A) LONGITUDINAL VIEW

DISCHARGE AIR EVAPORATOR

BULKHEAD WALL

RETURN AIR

FAN

CONDENSER

HEADER STACK

(B) HEADER STACK (C) REAR VIEW

Blower 

Duct
22

air from short-circuiting back to the refrigeration unit;

• do not load so high that the air chutes are

compressed and air circulation is blocked;

• allow at least 4 inches (10 cm) of open

space between the end of the load and the

rear doors for air return; and 

• provide adequate space for air return under

the load (figure 5). (If the floor channels

are less than 2 inches (5 cm) deep, the

product should be loaded on floor racks or

pallets with their stringers running lengthwise for greater airflow under the load.)

Unit Loads

To enhance cooling of unit loads on pallets

or slipsheets in trailers with top-air delivery:

• secure containers to each pallet with

appropriate strapping, tape, plastic film, or

netting; 

• load the pallets in rows and off the walls

(figures 12a and b);

• load the pallets with their stringers running

the length of the trailer; and

• secure the load with spacers and bracing to

prevent the product containers from toppling and blocking air spaces between the

walls and rows of pallets.

Loading Vehicles with 

Bottom-air Delivery

Design load patterns in bottom-air delivery

vehicles to maintain air pressure under the

load. Respiring produce should be packed in

boxes with top and bottom vent holes. 

For hand-stacked loads in vehicles with bottom-air delivery the following apply: 

• Load cartons tightly together from front 

to rear and sidewall to sidewall of the 

vehicle.

• Stack cartons with top and bottom vent

holes directly on top of each other with the

vent holes aligned.

• Leave at least 4 inches (10 cm) between

the top of the load and the ceiling for air to

return to the refrigeration unit.

• Block any space left open on the top of the

T-rails at the rear of the vehicle so that air

will be forced upward through the load and

not short circuit around the end of the load

at the doors (figure 3).

For unit loads on pallets or slipsheets in

vehicles with bottom-air delivery, observe

the following:

• Load the unit loads together as tightly as

possible. 

• Cover floor space not covered with the

unit loads with fiberboard or other appropriate material to force the air up through

the unit loads.

• Ensure that there are holes or slots in plywood pallet floors or slipsheets to allow

refrigerated air into the unit load.

• For nonfrozen loads, block the ends of the

pallets at the rear of the load to assure that

air pressure is maintained under the load.

Figure 11.

Rear view of an airflow

loading pattern modified

for wirebound crates. 
23

Figure 12. 

End and overhead views of

basic pallet or unit load patterns in a semi-trailer: (a) airflow, (b) center-loaded, (c) wallloaded, (d) off-set against

walls, and (e) pinwheel. (Note:

Pallets used in pinwheel patterns must be 4-way, or air flow

under the load will be blocked.) 

SPACER BLOCKS

(B) PALLETS

CENTER-LOADED

SPACER BLOCKS

SPACER BLOCKS

(A) PALLETS

AIRFLOW LOADED

(C) PALLETS

WALL LOADED

(D) PALLETS

OFFSET LOADED

(E) PALLETS

PINWHEEL LOADED

BULKHEAD WALL

BULKHEAD WALL

BULKHEAD WALL

BULKHEAD WALL

BULKHEAD WALL
24

The load patterns in figures 12c and d are

recommended for exporting palletized

grapes and tree fruit in van containers with

bottom-air delivery systems.

Unit or Pallet Loads

In top-air delivery trailers, unit or pallet

loads are usually loaded in one of five basic

patterns (figure 12). The dimensions of the

pallet base and the interior dimensions of

the vehicle will have considerable influence

on the pattern used. The amount of bulge,

overhang, whether top-iced, and ventilation

requirements are other determining factors

for unit load patterns. 

Design unit load patterns to reduce the

contact of the product with the walls and

floor of the vehicle, especially if the vehicle is not equipped with inverted ribbed

walls and deep channel or high airflow

floors. Figure 13 shows the effect of unit

and pallet load patterns on the amount of

product exposed to contact with wall and

floor surfaces. Reducing the amount of

surface contact will improve product

arrival temperatures and reduce the chance

of product freezing or warming in extreme

weather conditions. 

Stack shipping containers for unit loads

squarely on the pallets and stabilize to prevent toppling. Strapping, both vertical and

horizontal, is a popular method for stabilizing unit loads. This method can be enhanced

by the use of corner boards (figure 14).

Also, palletizing glue (which has strength in

shear and not in tension) may be used

between layers of containers. Net wraps and

plastic stretch or shrink film wraps also may

be used. 

CAUTION: Ensure that film wraps are not

used on products that are improperly precooled and/or have a high respiration rate as

the film may block ventilation and allow

heat buildup. The top two or three layers of

a unit load sometimes are cross-stacked

and/or taped horizontally for stabilization.

Brace unit loads to prevent them from shifting against the rear doors and blocking airflow around the end of the load. Figure 15

illustrates an easily constructed wooden

brace. Load lock bars also help prevent

shifting.

Some loads are partly unitized and partly

hand-stacked. In this case, put the handstacked portion on pallets to make it consistent with the rest of the load and allow better air circulation.

Vented Loads

In some cases, ambient air is vented through

trailers to cool loads of fresh produce. Also,

fresh air may be vented into the vehicle to

prevent oxygen starvation or to displace

metabolic gases such as ethylene or carbon

dioxide. For proper ventilated cooling of

hand-stacked loads, use an airflow loading

pattern (figure 10). In a vented load, the air

enters a vent door at the top front of the

trailer, travels down under the bulkhead,

through the horizontal air channels, and

exits at a vent at the bottom of the rear door. 

CAUTION: Ensure that the ambient air is

near the product’s desired transit temperature and not so cold or hot that it will injure

the product. The product may also be damaged if substantial amounts of heat or fumes

from the tractor’s exhaust stack are able to

enter through the front vent. When ventcooling loads, open all available vent doors

at the rear of the trailer.

For vented cooling of unitized loads, the

load patterns shown in figures 12a, b, and c

are preferred.

Top-iced Loads

Use the pattern shown in figure 16 for handstacked loads that will be top-iced. Stack

boxes or wirebound crates directly on top of

each other in lengthwise rows. Divide the

crosswise slack space evenly between the

rows and walls for top-ice to fill. Place

wood strips horizontally to stabilize the load

and maintain space between the rows. 

The recommended procedure is to apply the

crushed ice on top of the load in three

lengthwise windrows. The thermostat should
25

be set at 35oF (2oC) to allow the ice to melt

steadily during the trip. A colder setting may

crust or freeze the ice and block air circulation, thus allowing heat buildup in the interior of the load.

CAUTION: Ensure that the crushed ice is

not cold enough to freeze the produce on

contact. Ice may come out of cold storage as

cold as 25oF (–4oC).

Figure 13. 

Effect of different unit

load patterns on the percentage of cartons contacting the floor and

walls in a typical load of

a perishable product.

(a) WALL LOADED = 20%

PRODUCT ON SLIPSHEETS

(b) CENTER-LOADED = 5%

PRODUCT ON PALLETS

(c) WALL LOADED = 15% (d) CENTER-LOADED = 0%
( ) For both top- and bottom-air delivery

vehicles, avoid loading tight against flat

walls; use an offset-by-layers pattern for

hand-stacked loads or center-load unit

loads (figures 7, 10, and 12).

( ) Allow at least 4 inches (10 cm) of space

between end of load and rear doors for

return air.

( ) Use pallets on floor if floor channels or

ducts are less than 2 1/4 inches (6 cm)

deep.

( ) Secure hand-stacked loads at rear with

wood gates, load bars, or other devices.

( ) Secure unit loads with one or more of the

following: air bags, bracing, shrink film

or netting, or strapping. 

For palletized loads, the load patterns shown

in figures 12a and b are preferred.

Loading Checklist

Use the following checklist when loading

trailers with top-air delivery:

( ) Precool vehicle to desired thermostat 

setting.

( ) Shut off the refrigeration unit when loading at an open dock.

( ) Record product temperatures during 

loading.

( ) For hand-stacked loads, use an airflow

loading pattern with a header stack and

lengthwise air channels (figure 10). 

26

Figure 14.

Example of strapping

and corner boards on a

unit load.

Horizontal

Strap

Vertical Straps

Corner Boards
27

Figure 16. 

Rear view of a stacking

pattern with wood stabilizing strips for top-iced

loads in wirebound

crates (shown) or waxed

fiberboard boxes.

HORIZONTAL WOOD

STABILIZING

STRIPS

Figure 15. 

Example of a method for

bracing a load at the rear

doors.

Use wide board to fill

space between load

and door

Nominal 2x4

(approx. Nominal 1x4

(approx.
• Highest freezing point:

30.0oF (–1.1oC)

After harvest, most apples are held in bulk

bins in cold storage until they are sold. As

orders are received, apples are packed in

corrugated fiberboard boxes. After packing,

the apples are palletized for transport to the

loading dock. At the loading dock, they may

occasionally be removed from the pallets

and hand-stacked in the trucks. 

Apples ripen steadily at temperatures above

40oF (4oC): Therefore, refrigerate them

immediately after harvest. Hold and transport most varieties at the 30o to 32oF (–1o to

0oC) temperature range. Some varieties,

such as McIntosh, are subject to chilling

injury at long exposure to temperatures

below 38oF (3oC).

Transport apples taken from cold storage at

the same temperature at which they were

stored. Since most apples are shipped at

temperatures near their freezing point, they

are quite susceptible to freezing injury.

Thermostatically controlled heating should

be used to prevent both freezing and overheating in extremely cold weather.

Mature apples coming from cold storage

bruise more easily than those recently harvested and require more careful handling.

Apples absorb odors quite readily. They

should not be shipped in mixed loads of

commodities like onions or cabbage, nor in

trucks harboring strong odors. Apples also

produce ethylene, and they should not be

shipped with products sensitive to this gas.

Quality and shelf life at destination will

depend greatly on providing the recommended transport conditions. For loads with

more than one commodity, consult “Load

Compatibility Groups” in appendix II.

Make decisions on thermostat settings on a

load-by-load basis, taking into account the

operating characteristics of individual trailers, the loading temperature of the product,

and the desired transit temperature for the

product loaded. 

CAUTION: Be careful when determining

the thermostat setting for fresh or chilled

products transported at temperatures near

their freezing point. Considerable freezing

or chilling damage could occur, especially

on the top layer of the load. This is because

air exiting the refrigeration unit may be several degrees below the thermostat setting to

attain a cooling differential with the air at

the return. For example, if the desired transport temperature of a product is 32oF (0oC)

and the freezing point is 31.8oF (–0.1oC),

then the thermostat setting would probably

need to be in the 34o to 36oF (1.1o to 2.2oC)

range to prevent product freezing. 

Apples

Recommended transport conditions:

• Desired transit temperature:

Most varieties: 30o to 32oF (–1o to 0oC)

Cortland, McIntosh, and Yellow Newtown: 38o to 40oF (3o to 4oC)

• Desired relative humidity:

90 to 95 percent

28

V. Individual Commodity Requirements

Fresh Fruits and Vegetables
29

Recommended loading methods:

• Fiberboard boxes—Nearly all apples are

shipped in fiberboard boxes. The apples may

be packed in the boxes loose, in polyethylene

bags, or in molded trays. Stack the boxes

lengthwise or crosswise in the vehicle. 

• Fruit from cold storage—Stack the boxes

tightly together. However, in extreme hot or

cold weather, use an offset by layers pattern

for reduced contact with the walls and floor

(figure 7).

• Palletized fruit—Center-load (figure 12b)

in extreme hot or cold weather to reduce

contact with walls. Do not overfill bin loads

to prevent apples in the bottom bins from

being bruised. 

Apricots

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

30.1oF (–1.1oC)

Apricots should be firm when shipped, so

they will have a 1- to 2-week shelf life. Precool to the desired transit temperature. Some

shippers use forced-air coolers, while others

room cool their fruit. Apricots may be

shipped with other tree fruit commodities

from the same or nearby packing houses. If

apricots are shipped in mixed loads that are

top-iced, ice should not contact the apricots.

Recommended loading methods:

• Fiberboard boxes—Boxes of apricots generally are unitized on wood pallets. Secure

the boxes with straps or plastic netting. If

the apricots are not precooled to the transit

temperature, place fiberboard strips between

the stacks of boxes on the pallet so that cold

air may circulate freely around them. If the

weather is very hot and the trailer has flat

sidewalls, center-load the pallets to prevent

the transfer of heat from the walls to the

fruit (figure 12b).

Artichokes

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point:

29.9oF (–1.2oC)

• Top- or package-ice OK

Precool artichokes as soon as possible after

harvest to reduce wilting, weight loss, discoloration, and decay. Use top-ice to prevent

wilting or loss of turgidity and to keep the

buds near the desired transit temperature for

added shelf life. The marketability of artichokes is reduced by bruising or freezing.

Severe freezing turns the buds black and

slight freezing causes skin breaks and blisters. 

Recommended loading methods:

• Fiberboard boxes—Most artichokes are

packed in waxed fiberboard boxes which are

stacked on their bottoms either lengthwise

or crosswise on pallets. See figure 12 for

unit load patterns. 

Asparagus

Recommended transport conditions:

• Desired transit temperature:

32o to 35oF (0o to 2oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point:

30.9oF (–0.6oC)

Asparagus is highly perishable. Speed and

care are required during handling and transit

to prevent excessive loss of quality. As soon

as asparagus is cut, its natural sugars, flavor,

and vitamin C begin to diminish rapidly,

particularly at temperatures above 36oF

(2oC). Hydrocooling is the most desirable

method of precooling.

Asparagus is usually packed in bunches and

set upright in the shipping container to prevent bruising and curling of the tender tops.
30

To prevent moisture loss and preserve crispness during transit, place pressed paperboard

or other water-retaining material in the bottom of the pyramid-shaped wooden box or

waxed corrugated fiberboard box. 

A modified atmosphere of about 7 percent

CO2 is beneficial in preventing decay and

toughening of fresh asparagus. This is especially true if temperature control cannot be

brought below 41oF (5oC).

Recommended loading methods:

• Nailed wooden boxes (pyramid-shaped)—

Load boxes lengthwise on their bottoms and

stack in register. The slope of the pyramid

allows open space for continuous lengthwise

air channels on each layer in hand-stacked

loads. For palletized loads, use a center-load

pattern as shown in figure 12b.

• Fiberboard boxes (waxed corrugated)—

Load boxes lengthwise or crosswise on their

bottoms and palletize. Use a center-load pattern as shown in figure 12b.

Avocados

Recommended transport conditions:

• Desired transit temperature:

Cold-tolerant varieties:

Such as Lula and Booth No. 8 

40oF (4oC)

Cold-intolerant varieties: 

All West Indian varieties, which include

Fuchs, Pollack, and Walden

55oF (13oC)

• Desired relative humidity:

85 to 90 percent

• Highest freezing point:

31.5oF (–0.3oC)

A few varieties, such as Fuerte, are best

shipped at 45oF (7oC). Gradual ripening of

avocados may occur at temperatures as low

as 45oF (7oC). The rate of ripening and softening of the fruit increases as the temperature rises. Therefore, it is important to precool avocados before loading. Below

recommended temperatures, avocados are

susceptible to chilling injury. Common

symptoms of chilling injury are a grayishbrown discoloration of the flesh, scalding

and/or pitting of the skin, and failure of the

fruit to ripen satisfactorily after storage or

transit. At temperatures higher than recommended, anthracnose or black spot can

become serious disorders.

Recommended loading methods:

• Fiberboard boxes—Both California and

Florida shippers use fiberboard boxes for

packing avocados. Shippers in both areas

predominantly use a one- or two-layer box,

and generally palletize their avocados. For

hand-stacked loads, use an airflow pattern

(figure 10). For transport in extremely cold

weather, center-load pallets in vehicles without ribbed walls to prevent chilling injury

(figure 12b). 

Bananas

Recommended transport conditions:

• Desired transit temperature:

56o to 58oF (13o to 14oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

30.6oF (–0.8oC)

Bananas are imported into the United States

year-round from various Central and South

American countries. The Cavendish variety

is most commonly imported. Bananas are

shipped green and ripened at destination.

They are very temperature sensitive; lower

than desired temperatures will cause chilling

injury, and higher than desired temperatures

may cause rapid and improper ripening.

Proper air circulation is required to maintain

uniform temperatures throughout the load,

since fluctuating temperatures are detrimental. Provide a fresh air vent to prevent ethylene gas buildup inside the trailer which will

cause premature ripening. Also, do not ship

bananas with other produce that is not temperature compatible or that produces high

amounts of ethylene.

Recommended loading methods:

• Corrugated fiberboard boxes—Nearly all

bananas are packed in heavy duty, plastic
31

film-lined fiberboard boxes at the country of

origin. The gross weight of the boxes is 40

pounds (18 kg). They then are transported to

the United States in refrigerated containers

or on break-bulk ships under carefully controlled temperature and humidity conditions.

Since bananas are easily bruised, do not

throw or drop the boxes during handling.

Place the boxes on their bottoms, and do not

invert or stack them on their sides. If not palletized, load the boxes crosswise or lengthwise and stack tightly together to get a dense

load. In extremely cold weather, use floor

racks or pallets in vehicles without deep Trail floors to prevent freezing or chilling

injury. If the walls are not grooved, centerload pallets off the walls (figure 12b). Handstack boxes in an offset by layers pattern

(figure 7a) to reduce contact with the walls.

Beans (green, snap, or pole)

Recommended transport conditions:

• Desired transit temperature:

40o to 45oF (4o to 7oC)

• Desired relative humidity:

95 percent

• Highest freezing point:

30.7oF (–0.7oC)

Green or snap beans are highly susceptible

to chilling injury which predisposes them to

russeting and other discoloration. Temperatures in the 40o to 45oF (4o to 7oC) range

are considered best for shipping beans, even

though some varieties may incur some chilling injury after several days at 45oF (7oC).

At temperatures above 50oF (10oC), beans

may decay rapidly. Precool beans before

shipment but do not pack wet, as this will

increase the chance of russeting and decay.

Use of a controlled atmosphere in the 2 to 3

percent oxygen and 5 to 10 percent carbon

dioxide ranges will help retard yellowing of

green beans. Green beans also are sensitive

to ethylene and should not be shipped with

ethylene producers. 

Recommended loading methods:

Stack and load containers of green beans to

allow maximum air circulation for respiration heat removal.

• Wirebound crates—Load wirebound crates

lengthwise on their bottoms in an airflow

pattern (figure 11).

• Fiberboard boxes—Load fiberboard boxes

in an airflow pattern (figure 10). Increasingly, fiberboard boxes and wirebound crates of

beans are palletized. Pallet patterns shown

in figures 12a, b, or c allow good air circulation if pallets are properly secured. 

Beans (lima, in pods)

Recommended transport conditions:

• Desired transit temperature:

41o to 43oF (5o to 6oC)

• Desired relative humidity:

95 percent

• Highest freezing point:

31oF (–0.6oC)

Fresh lima beans in pods will keep from 5 to

7 days if held and shipped within the desired

temperature range. Higher holding temperatures will greatly reduce the market life of

the beans.

Precool lima beans immediately after harvest, preferably by hydrocooling. The pods

are susceptible to chilling injury below the

recommended transit temperature. Chilling

injury results in rusty-brown specks on the

pods.

Recommended loading methods:

• Wirebound crates and waxed fiberboard

boxes—Hand-stack boxes and crates in an

airflow pattern (figures 10 and 11).

• Palletized loads—See figure 12 for illustrations of unit load patterns.

Beets 

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

98 to 100 percent
32

• Highest freezing point

Tops, 31.3oF (–0.4oC)

Roots, 30.3oF (–0.9oC)

• Top-ice OK

Beets are shipped bunched with tops or

loosely packed without tops. Those shipped

in bunches are highly perishable because of

the heat generated by the tops. They should

be both package- and top-iced for maximum

refrigeration and moisture retention. The

leaves of bunched beets are especially susceptible to bacterial soft rot. Transit and

marketing losses caused by this disease can

be controlled by rapid precooling and maintenance of temperature at 32oF (0oC). 

Late-crop beets are topped and may be

shipped immediately or stored for later shipment. They are fairly decay resistant as long

as their skins are not broken and cool temperatures are maintained. However, it is

desirable to top-ice long distance shipments

in hot weather.

Recommended loading methods:

• Bunched in wirebound crates—Load crates

lengthwise on their sides. If top-iced, stack

directly on top of each other and leave 1

inch (2.5 cm) or more between the lengthwise rows for ice to fill (see figure 12). If

not top-iced, precool the beets, and use an

airflow loading pattern (figure 11).

• Topped in wirebound crates—Hand-stack

crates of topped beets in an airflow pattern

(figure 11). If beets are top-iced, see figure 16.

• Palletized—See “Unit and Pallet Loads” in

section IV, and figure 12b.

Beet Tops

Beet tops have essentially the same transit

and handling requirements as fresh spinach.

See “Spinach” in this section.

Blackberries

Recommended transport conditions:

• Desired transit temperature:

31o to 32oF (–0.6o to 0oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

30.5oF (–0.8oC)

Fresh blackberries are highly perishable.

They usually are not shipped over long distances by truck since their shelf life is limited to a few days. Maintaining their temperature near the desired 32oF (0oC) is very

important. An atmosphere of 10 to 20 percent carbon dioxide (CO2) will help to retard

decay.

Recommended loading methods: 

• Fiberboard trays—Corrugated fiberboard

trays usually interlock with the trays above.

Hand-stack trays lengthwise on their bottoms with space between the rows for airflow. Place wood strips crosswise about

every fourth layer for stabilization. 

Most shippers palletize the trays of berries

to minimize handling. Strap the trays securely to the pallets. Center-load the pallets,

two-wide, and brace away from the walls, so

that air can circulate around the load and

eliminate the conduction of heat from the

trailer walls to the fruit. Major shippers

enclose the pallet loads of berries with airtight plastic bags and inject a modified

atmosphere for increased protection against

decay and extended shelf life (figures 12b

and 17).

Blueberries

Recommended transport conditions:

• Desired transit temperature:

31o to 32oF

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

29.7oF (–1.3oC)

Blueberries are very temperature sensitive.

Temperatures much above the desired holding temperature cause over-ripening, shriveling, and loss of shelf life. Avoid moisture on

berries caused by condensation or other

sources, while in transit. A minimum of handling, close temperature control, and expedited shipment and marketing are essential

for successful sales since blueberries have a
33

shelf life of only about 2 weeks under optimum conditions. Modifying the atmosphere

with CO2 in conjunction with refrigeration is

effective in retarding decay in blueberries

but may result in off-flavors.

Recommended Loading Methods:

• Fiberboard Trays—Blueberries are generally packed in film-covered pint- (0.47-l)

sized containers. A plastic film cap is tightly

secured on each container by a rubber band.

Berries also may be packed in clear clam

shell container. Twelve containers of berries

are packed in a fiberboard tray. The trays are

nearly always palletized for shipment. Center-load the pallets, and brace away from the

wall, eliminating the conduction of heat

from the trailer walls to the fruit (figure

12b).

Broccoli

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point:

30.9oF (–0.6oC)

• Top- and/or package-ice desirable

The respiration rate of broccoli is among the

highest for vegetables. Therefore, refrigeraFigure 17. 

A palletized load of

strawberries, centerloaded. (Note: Each pallet load is enclosed in an

airtight plastic bag

injected with a modified

atmosphere.)
34

tion at or just above the desired transit temperature is required at all times. Exposing

broccoli buds to temperatures above 50oF

(10oC) for only a short while will result in

yellowing and reduced marketability. Provide fresh air exchange in the trailer to prevent anaerobic respiration and undesirable

odors. Broccoli is sensitive to ethylene, so

do not ship it with fruit, such as apples or

pears, that produce substantial amounts of

ethylene, because this gas will cause yellowing of the buds.

Recommended loading methods:

Broccoli is usually packed in waxed fiberboard boxes with crushed ice. After the

boxes are loaded, top-ice the load.

• Fiberboard boxes—Load boxes lengthwise on their bottoms. Align rows with

space between them for top-ice (figure 16).

When the boxes have top and bottom ventilation slots, stack them in register, so that

melt-water from the ice can run down

through the product. Load hand-stacked

boxes that are not top-iced in an airflow

pattern (figure 10). Load top-iced, palletized loads of broccoli in any of the unit

load patterns shown in figure 12.

Note: If shrink film is used to secure the

pallet loads, make sure the film does not

cover the top, so melt-water can filter down

through the broccoli.

Brussels Sprouts

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point:

30.5oF (–0.8oC)

• Top- and/or package-ice OK

Keep brussels sprouts near the desired 32oF

to attain the maximum shelf life of 3 to 5

weeks. At 41oF the deterioration rate of

brussels sprouts doubles. Do not ship them

with ethylene-producing fruit, because brussels sprouts will yellow. Use perforated plastic package liners to help prevent moisture

loss from transpiration. A controlled or modified atmosphere of 2.5 to 5 percent oxygen

and 5 to 7.5 percent carbon dioxide atmosphere helps maintain the quality of brussels

sprouts at 41oF or 50oF, but not at 32oF.

Recommended loading methods:

Brussels sprouts are shipped mostly in

waxed fiberboard cartons with package- or

top-ice. Use the same loading procedures as

those for broccoli. See preceding entry,

“Broccoli.” 

Cabbage

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

98 to 100 percent

• Highest freezing point:

30.4oF (–0.9oC)

Cabbage is less perishable than many other

leafy vegetables. Wilting from moisture loss

is the main cause of damage during handling

and transporting. Stored cabbage is less likely to wilt during transit than new cabbage.

Except for a few new crop shippers, most

shippers do not top-ice cabbage. Stored cabbage should not be top-iced. Several kinds

of decay, such as bacterial soft rot and

watery soft rot, may damage cabbage during

transit if the desired temperature is not

maintained.

Recommended loading methods:

• Wirebound boxes—Load boxes lengthwise

on their bottoms. Most shippers offset the

crates by layers to take up slack space and

stabilize the load (figure 7a). Use an airflow

pattern (figures 10 and 11) for crates of new

cabbage that are not top-iced. If top-iced,

load the crates lengthwise in rows with the

slack space evenly divided between the rows

(figure 16).

• Fiberboard boxes—Load boxes lengthwise

on their bottoms in an airflow pattern (figure

10). For palletized loads, see figure 12.
35

Cantaloupes

Recommended transport conditions:

• Desired transit temperature:

36o to 41oF (2o to 5oC)

• Desired relative humidity:

95 percent

• Highest freezing point:

29.9oF (–1.2oC)

• Top-ice OK

After harvest, cantaloupes are forced-air or

hydro-cooled to prevent them from becoming soft during long-distance transport.

Although they are chill sensitive, cantaloupes are not harmed by extended contact

with ice. Up to 10 lbs (4.5 kg) of crushed

ice may be placed in boxes of cantaloupes

after they are packed. Or, the loads may be

top-iced if the cantaloupes are packed in

moisture resistant boxes.

Cantaloupes picked at the hard-ripe stage of

maturity are subject to chilling if held at

temperatures below 36oF (2.2oC) for longer

than 1 week. For normal truck shipments of

less than 1 week, temperatures between 32o

and 34oF (0o to 1oC) will not be harmful. 

Cantaloupes produce ethylene, so do not

ship in mixed loads with ethylene-sensitive

products such as green leafy vegetables.

Recommended loading methods:

• Fiberboard boxes—Stack boxes holding 9

to 23 cantaloupes each, six or seven layers

high on pallets. Load the pallets, two across,

the width of the truck. If top- or package-ice

is used, the boxes must be moisture resistant,

and floor drains should be open so that meltwater will not accumulate on the trailer floor.

See figure 12 for pallet loading patterns. 

Carrots

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

98 to 100 percent

• Highest freezing point:

29.5oF (–1.4oC)

• Top-ice OK

Hydrocool carrots after harvest to ensure an

adequate shelf life. Top-ice topped carrots

for moisture retention. Carrots are shipped

to market loose in bulk bags or fiberboard

boxes or packed in consumer size plastic

bags within larger mesh bags or in fiberboard boxes. Do not ship carrots with ethylene-producing commodities, because this

will cause the carrots to have a bitter flavor.

Recommended loading methods:

• Open mesh or plastic film bags—Carrots

in bags usually are stacked so that, when

loaded, the carrots are in a vertical position.

Load hand-stacked bags in rows with spaces

between for top-ice. Wrap palletized loads

with net, or strap for stability. See figure 12

for pallet load patterns.

• Corrugated fiberboard boxes (waxed)—

Carrots usually are packed horizontally in

fiberboard boxes. Hand-stack boxes lengthwise on their bottoms in an airflow pattern

(figure 10). Column-stack boxes loaded on

pallets or slipsheets in the lower layers to

retain their strength. Cross-stack the boxes

in the upper layers for stability. See figure

12 for pallet load patterns. 

Cauliflower

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 98 percent

• Highest freezing point:

30.6oF (–0.8oC)

• Top-ice OK

Precool cauliflower by vacuum or hydro

methods before loading. To control decay,

keep cauliflower below 40oF (4oC). If cauliflower is packed in moisture resistant boxes,

it can be top-iced. Take care not to bruise the

buds or heads during loading and handling.
36

Recommended loading methods:

• Corrugated fiberboard boxes—Hand-stack

boxes in an airflow pattern (figure 10). Most

West Coast loads are packed in single-layer

boxes and palletized. Do not load the pallets

so high that the top layer of boxes compress

the air-delivery chute and restrict airflow.

This may result in poor air circulation and

warm or freezing spots in the load. See figure 12 for pallet loading patterns.

• Wirebound crates—Hand-stack crates in

an airflow pattern (figures 10 and 11).

Celery

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

98 to 100 percent

• Highest freezing point:

31.1oF (–0.5oC)

• Top-ice OK

Soon after harvest, precool celery to below

40oF (4oC) by either hydrocooling or vacuum cooling to limit decay. After harvest celery continues to grow, so pack it upright in

the container. Sometimes celery is sleeved

or bagged at the shipping point. The sleeves

help retain moisture and prevent wilting

which is a main cause of deterioration.

Some shippers who use wirebound crates

top-ice their celery, but this practice is not

required if the celery is sleeved.

Recommended loading methods:

• Wirebound crates—Load crates lengthwise on

their sides to protect the stalks from damage and

allow the celery to grow straight. Hand-stack topiced celery in rows with spaces between for topice to fill (figure 16). If not top-iced stack in an airflow pattern (figures 10 and 11). 

• Fiberboard boxes—Most celery that is

packed in fiberboard boxes is vacuum-cooled

and, therefore, not top-iced. Load the boxes

lengthwise on their sides. Load boxes packed

with celery hearts lengthwise on their bottoms. In either case, load hand-stacked boxes

in an airflow pattern (figure 10). 

Considerable amounts of crated and boxed

celery are palletized. Figure 18 shows a

mixed palletized load of celery and green

onions loaded in the recommended airflow

pattern. See “Unit or Pallet Loads” section

and figure 12a. 

Cherries

Recommended transport conditions:

• Desired transit temperature:

Sweet cherries: 30o to 32oF (–1o to 0oC)

Sour cherries: 32oF (0oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

Sweet cherries: 28.8oF (–1.8oC)

Sour cherries: 29.0oF (–1.7oC)

Cherries are highly perishable, so refrigerate

to the desired transit temperature before

loading. In conjunction with refrigeration,

consider using a modified atmosphere with

up to 20 percent CO2 to maintain the quality

of cherries during transit.

Washington and Oregon cherry shippers

place a polyethylene bag liner in the box.

Respiration of the fruit in the bag will build

up a sufficient concentration of CO2 to

retard decay and help maintain a fresh

appearance. However, the liners should be

slit at destination to eliminate gas buildup

and off flavors. California shippers do not

use box liners. Increasingly pallet lots of

cherries enclosed in plastic bags and treated

with a modified atmosphere are being

shipped.

Recommended loading methods:

• Wooden lugs—Most cherries are volumefilled. Unitize on pallets, and secure with

strapping or plastic netting. See figure 12 for

pallet load patterns.

• Corrugated fiberboard boxes—Increasing

amounts of cherries are shipped in fiberboard boxes. Like the wooden lugs, they

may be secured to the pallets with vertical

and horizontal bands or plastic netting. See

“Unit or Pallet Loads” section and figure 12

for information on pallet loading.
37

Corn (sweet)

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 98 percent

• Highest freezing point:

30.9oF (–0.6oC)

• Top-icing very desirable

The sugar in freshly harvested sweet corn

will turn to starch rapidly unless field heat is

removed quickly. At room temperature, corn

can lose 50 percent of its sugar in 24 hours.

However, if the temperature is lowered to

32oF (0oC) soon after harvest, only 24 percent is lost in 4 days. Many newer varieties

of corn retain their sugar content for longer

periods than older varieties. In most growing

areas, corn is hydrocooled, and in some

areas, it is vacuum-cooled.

Corn has a high respiration rate and requires

maximum refrigeration during transit. Topicing retains moisture and maintains a low

temperature in corn during transit. If the

corn is vacuum-precooled, top-icing is especially desirable to replace moisture lost from

the husks. When the load is top-iced, set the

thermostat at 36oF (2oC) so that the ice will

melt. If the thermostat is set at or below

freezing, ice may crust on top of the load

and block air circulation and keep meltwater from cooling corn in the bottom of the

load.

Prepackaging several ears of corn in filmcovered trays for retail at the grower level is

a rapidly growing practice. The trays are

Figure 18. 

A mixed palletized load

of celery and green

onions loaded in a unit

load airflow pattern.
38

subsequently packed in fiberboard boxes for

shipment. Do not top-ice these boxes. If

corn is not top-iced, ship it at 32oF.

Recommended loading methods:

• Wirebound crates—The majority of Florida sweet corn is shipped in wirebound crates

loaded lengthwise on their sides. Align

rows, keeping adequate space between them

to allow for top-ice (figure 16). Another

loading pattern calls for loading the crates

lengthwise on their sides with no space

between rows in the first two or three layers.

The upper layers have one less row and are

offset over the bottom layers with several

inches of space between rows. Place wooden

strips horizontally across the top of each

layer to prevent the crates from toppling and

blocking the space between rows. This loading method allows a large volume of top-ice

to get between the rows in the upper layers

and melt water to run directly through the

bottom layers.

• Fiberboard boxes—Load boxes lengthwise

on their bottoms. Moisture-resistant fiberboard boxes have openings only in the top

and bottom for top-ice melt-water to run

down through the layers. Stack these boxes

in register or squarely over each other so the

melt-water can run down through all of the

layers of the stack.

Load boxes or crates without top-ice in an

airflow pattern (figures 10 and 11). Load

pallets as shown in figure 12a or 12b to

assure maximum top-ice infiltration in topiced loads or air circulation in loads without

top-ice.

Cranberries

Recommended transit conditions:

• Desired transit temperature:

36o to 40oF (2o to 4oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

30.4oF (–0.9oC)

Cranberries are primarily grown in Wisconsin, Massachusetts, New Jersey, Oregon, and

Washington, and are harvested and available

for fresh distribution from September

through December. Cranberries can be held

at temperatures of 36o to 40oF (2o to 4oC)

up to 4 months. Cranberries will tolerate

temperatures as low as 32oF (0oC) for up to

2 weeks. However, exposure for longer periods could cause chilling damage resulting in

discoloration and rubbery texture. Handle

cranberries with care since they are susceptible to bruising. Precool cranberries to near

40oF (4oC) before loading, because the insulation effect of the packaging makes it difficult to lower temperature during transit.

Recommended loading methods:

• Fiberboard master cartons—Cranberries

for the fresh market are packed in 1-lb

(0.45-kg) film bags or window boxes and

shipped in master fiberboard containers that

will hold 24 1-lb packages. For handstacked loads, stack the master fiberboard

cartons lengthwise on their bottoms in an

airflow pattern (figure 10).

For palletized loads, center-load as shown in

figure 12b.

Cucumbers

Recommended transport conditions:

• Desired transit temperature:

50o to 55oF (10o to 13oC)

• Desired relative humidity:

95 percent

• Highest freezing point:

31.1oF (–0.5oC)

Generally, cucumbers do not require precooling before transit. However, store them

so that excess field heat will be removed

within 24 hours after harvest, or yellowing

will occur. Yellowing also may occur if

cucumbers are shipped in mixed loads with

tomatoes or other ethylene-producing products. Cucumbers are subject to chilling

injury if held or transported for longer than

2 days at temperatures below 50oF (10oC).

Decay is controlled by maintaining transit

temperatures near desired levels. However,

at higher temperatures bacterial diseases can

be a problem. Cucumbers are very susceptible to shriveling, so keep humidity high during storage and transit. Also, cucumbers

usually are waxed to prevent shriveling.
39

Recommended loading methods:

• Fiberboard boxes—Most cucumbers are

packed in various sizes of fiberboard boxes.

Load hand-stacked boxes lengthwise on

their bottoms in an airflow pattern (figure

10). Many shippers palletize their cucumbers. See “Unit or Pallet Loads” section for

pallet loading patterns.

Eggplants

Recommended transport conditions:

• Desired transit temperatures:

46o to 54oF (8o to 12oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

30.6oF (–0.8oC)

Some eggplant fruit are subject to chilling

injury at 50oF (10oC) and below. Surface

scald or bronzing and pitting are symptoms

of chilling injury. Chilled eggplants are subject to Alternaria rot when removed from

storage or transit. Chilling sensitivity varies

by season of harvest, variety, and maturity.

Overmature fruit harvested in the fall is less

sensitive to chilling than mature fruit harvested in the summer. Mature eggplants harvested midsummer are highly susceptible to

decay at temperatures higher than 54oF

(12oC) and chilling injury below 50oF

(10oC). Eggplants shrivel very easily during

transport and storage if the relative humidity

is not kept at 90 percent.

Recommended loading patterns:

• Fiberboard boxes—Most eggplants are

packed in fiberboard boxes. Generally, load

hand-stacked boxes lengthwise on their bottoms in an airflow pattern (figure 10). Many

shippers palletize their eggplant boxes eight

per layer and five to six layers high. Load

pallets in an off-wall pattern (figure 12b).

Endive and Escarole

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point:

31.9oF (–0.1oC)

• Top-ice desirable

Endive and escarole are highly perishable

leafy vegetables, similar to lettuce, which

require maximum refrigeration during transit. They have a high rate of respiration, so

precool immediately after harvest by vacuum or hydrocooling. Endive and escarole

often are shipped in mixed loads with other

products, because most orders for these

products are for less than truckload lots.

Top-ice or package-ice is desirable. If topice is applied to the load, set the thermostat

on the refrigeration unit at 36oF (2oC) so

that the ice will melt slowly and run down

through the load. If not top-iced, ship the

product at 32oF (0oC).

Recommended loading methods:

• Fiberboard boxes (waxed)—Load the

boxes lengthwise on their bottoms in an airflow pattern, if not top-iced (figure 10). If

top-iced, stack the boxes lengthwise or crosswise in rows, directly on top of each other so

the melt-water can run down through the top

and bottom vent holes (figure 16).

• Wirebound crates—Load crates lengthwise

on their bottoms in an airflow pattern (figures 10 and 11). If top-iced, stack the crates

with slack space evenly divided between the

rows (figure 16).

Use unit load patterns (figure 12a or b) for

palletized loads of endive or escarole to

assure space for air circulation or top-ice

infiltration.

Garlic (dry)

Recommended transport conditions:

• Desired transit temperature:

32o to 34oF (0o to 1oC) 

• Desired relative humidity:

65 to 70 percent

• Highest freezing point:

30.5oF (–0.8oC)
40

Garlic is usually shipped from storage at

32oF (0oC). In warm weather, take care to

load the garlic promptly to reduce moisture

condensation on the product. Load in an airflow pattern to remove any condensation

that does occur. Garlic cloves sprout rapidly

at temperatures above 40oF (4oC). Do not

ship garlic in mixed loads with odor absorbing commodities. Do not allow ice to come

in contact with garlic. 

Recommended loading methods:

• Fiberboard boxes—Load the boxes lengthwise on their bottoms in an airflow pattern

(figure 10). This pattern assures good ventilation of the load to remove condensation

and maintain desired transit temperature. For

palletized shipments, use load patterns

shown in figures 12a and b.

Grapefruit

Recommended transport conditions:

• Desired transit temperatures:

Arizona and California: 58o to 60oF 

(14o to 16oC)

Florida and Texas:

Before January 1—60oF (16oC)

After January 1—50oF (10oC)

• Desired relative humidity:

85 to 95 percent

• Highest freezing point:

30oF (–1.1oC)

Grapefruit are very susceptible to chilling

injury, particularly early in the season. Chilling injury symptoms are pitting or physiological breakdown on the surface of the fruit

which can be a means of entry for decay

organisms. Many types of decay organisms

can attack grapefruit, particularly during

early- and late-season shipments. Most shippers treat their grapefruit with approved

fungicides. Curing or preconditioning grapefruit can counteract some of the adverse

effects of low temperature. To cure grapefruit, hold at 60oF (16oC) for 1 week. After

curing, store or ship grapefruit at temperatures of 32o to 34oF (0o to 1oC) for up to 21

days. Cured grapefruit may be stored or

shipped with oranges at low temperatures. 

Ventilate grapefruit loads during transit in

cool weather. However, during warm weather, refrigerate the loads. 

CAUTION: 41oF (5oC) is the temperature

at which the danger of chilling injury to

grapefruit is the greatest.

Recommended loading methods:

• Fiberboard boxes (loose filled)—Load

boxes lengthwise or crosswise on their bottoms. Hand-stack loads in an airflow pattern

(figure 10). Florida shippers mainly unitize

their shipments on slipsheets. Many California, Arizona, and Texas shippers unitize

their shipments on pallets. See figure 12 for

unit load patterns.

• Fiberboard boxes (bag master)—Load

boxes lengthwise or crosswise on bottoms.

Hand-stack bag-master boxes in an airflow

pattern (figure 10). Many bag-master boxes

are unitized on slipsheets or pallets. Since

most shippers do not precool their fruit, take

extreme care in transporting grapefruit in

bag masters. The fruit is packed in polyethylene film or mesh bags and packed in

boxes which makes it more difficult to cool

the fruit in transit. Use the unit load patterns

in figure 12a or b for bag-master packed

grapefruit that has not been precooled.

Grapes

Recommended transport conditions:

• Desired transit temperatures:

American types—Catawba, Concord,

etc.: 32oF (0oC)

European types (vinifera)—Thompson

seedless, Red Emperor, etc.: 31oF 

(–0.5oC)

• Desired relative humidity:

American: 90 to 95 percent

European: 85 percent

• Highest freezing point:

American types: 29.7oF (–1.3oC)

European types (vinifera): 28.1oF 

(–2.2oC)

Precool grapes to their desired transit temperature before loading, and maintain the

temperature during transit. Normally, fumigate vinifera grapes with sulphur dioxide
41

gas (SO2) during storage and before shipment to control the spread of Botrytis (gray

mold) and Cladosporium decays. This fumigation will not kill infections that started

before harvest. For grapes that are packed

for export, use top cushion pads that contain

sodium bi-sulphite which will be slowly

released during transportation. Do not ship

grapes treated with SO2 with other products

since the gas odor may be absorbed.

Do not ship grapes with green onions, as

they may absorb the onion odor. Also, prevent grapes from coming in contact with ice. 

WARNING: When using SO2 gas, take care

to prevent injury to workers and equipment.

SO2 fumes are toxic to humans and will corrode certain metals.

Recommended loading methods:

• Wood and kraft veneer, fiberboard, and

polystyrene foam boxes—Load hand-stacked

boxes lengthwise on their bottoms in an airflow pattern (figure 10). Most shipments of

grapes are palletized. See figure 12 for pallet

load patterns. Use patterns shown in figures

12c and d for export grapes loaded in van

containers with bottom-air delivery systems.

Kale

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point:

31.1oF (–0.5oC)

• Top-ice OK

Kale, a leafy vegetable, has a high rate of

respiration. It requires maximum refrigeration during handling and transit to maintain

its quality. When kale is transported or kept

at temperatures above 32oF (0oC), it may

temporarily appear to be in good condition.

However, the higher temperatures will

reduce its resistance to decay and yellowing

of the leaves, and it will break down rapidly

when displayed in stores.

To precool and to maintain crispness, pack

crushed or slush-ice in each container of

kale. Spread a liberal amount of top-ice over

loads which are not prepackaged.

Recommended loading methods:

• Wirebound crates—Align the crates with

space divided between the rows for top-ice

to fill (figure 16). If not top-iced, load crates

in an airflow pattern (figures 10 and 11).

• Fiberboard boxes (waxed and unwaxed)—

Load waxed boxes packed with loose kale in

straight rows with space divided between

the rows for top-ice to fill (figure 16).

Prepackaged kale needs cold air circulated

to each box. Use an airflow pattern for

hand-stacked loads (figure 10). For palletized loads going into a wide trailer, use

the pallet loading patterns (figure 12a or b)

to allow air to circulate around the product.

Kiwi Fruit

Recommended transit conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

29.0oF (–1.7oC)

Cool kiwi fruit to 32oF (0oC) as soon after

harvest as possible, and maintain that temperature during transit. Take care to prevent

kiwi fruit from being exposed to ethylene

gas. Use electric forklift trucks to handle

kiwi fruit, since they do not produce ethylene as propane-fueled trucks do. Do not

ship kiwi fruit in mixed loads with products

that generate ethylene, such as apples and

other tree fruit.

Recommended loading methods: 

• Wood trays and fiberboard boxes—Load

trays and boxes lengthwise on their bottoms.

Most boxes of kiwi fruit are palletized for

shipment. See figure 12 for pallet loading

patterns.
42

Lemons

Recommended transport conditions:

• Desired transit temperature:

45o to 55oF (7o to 13oC)

• Desired relative humidity:

85 to 90 percent

• Highest freezing point:

29.4oF (–1.4oC)

Lemons are subject to chilling injury (pitting

and physiological breakdown) if stored for

long periods at temperatures below 58oF

(14oC). However, during domestic transit

periods of several days, rot and mold are

more likely to damage lemons than cold. For

transit and storage periods up to 4 weeks,

lemons may be held at any convenient temperature between 45o and 55oF (7o to 13oC)

without incurring chilling injury. Lemons

usually are shipped from cold storage and

are near the desired transit temperature

when loaded. They may be ventilated if outside temperatures fall within the desired

temperature range.

Recommended loading methods:

• Corrugated fiberboard boxes—Nearly all

lemons consumed in the United States are

produced in Arizona and California. The

lemons are usually packed in fiberboard

boxes and palletized for shipment. See figure 12 for pallet loading patterns. 

Lettuce (head)

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

98 to 100 percent

• Highest freezing point:

31.7oF (–0.2oC) 

Lettuce is one of the most perishable and

easily damaged of all commercial vegetables. Individual lettuce heads usually are

field packed unwrapped or wrapped in plastic film, then packed in fiberboard boxes.

Vacuum-cool field-packed lettuce, and place

in cold rooms until ready for loading. Or

vacuum-cool the lettuce immediately before

loading. Because it is difficult to cool lettuce in transit, take several product temperatures during loading to make sure that the

lettuce is near the desired transport temperature. Lettuce is sensitive to ethylene gas,

so do not load it with ethylene-producing

commodities. In extreme temperatures, load

lettuce up off the floor on pallets or floor

racks and away from the side walls of the

trailer to prevent warming or freezing. Do

not ice lettuce.

Recommended loading methods:

• Fiberboard boxes—Lettuce boxes usually

are unitized and mechanically loaded.

Many different types of load patterns are

used, depending on the individual shipper’s equipment. Since lettuce heads are of

low density and high cube, there is a tendency to load it tightly, without air channels. Extremely tight loads, especially in

trailers with flat walls, may overheat or

freeze in extreme temperatures. During hot

weather, load the lettuce on disposable

wooden floor racks to allow additional airflow under the load. See figure 12 for pallet load patterns. In hot weather, use pattern 12b. Load hand-stacked boxes in an

airflow pattern (figure 10). 

Lettuce (leaf)

Recommended transport conditions: 

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

98 to 100 percent 

• Highest freezing point:

31.7oF (–0.2oC)

All varieties of leaf lettuce (Bibb, Boston,

butter, etc.) are very perishable and easily

damaged. Precool leaf lettuce immediately

after harvest by either vacuum or hydrocooling. Once lettuce is precooled, ship it as

near to 32oF (0oC) as possible and at high

relative humidity. At higher temperatures,

the rate of respiration is high, and bruised

areas will disease rapidly. Bacterial soft rot

is the most serious lettuce disease. 
43

Recommended loading methods: 

• Fiberboard boxes (waxed)—Load handstacked boxes lengthwise on their bottoms

in an airflow pattern (figure 10). There are

many kinds and sizes of fiberboard boxes

used for shipping leaf lettuce. However,

most shippers pack 12 or 24 bunches per

box. If palletized, see figure 12 for loading

patterns. Use the pattern shown in figure

12b for shipments in extreme temperatures.

• Wirebound crates—Load crates lengthwise

on their bottoms in an airflow pattern (figures 10 and 11).

Limes

Recommended transport conditions:

• Desired transit temperature:

48o to 50oF (9o to 10oC)

• Desired relative humidity:

85 to 90 percent

• Highest freezing point:

29.1oF (–1.6oC)

Limes are picked green and should remain

green during marketing for best quality.

After harvest, limes are sorted, packed and

precooled to around 50oF (10oC) in refrigerated rooms. Limes are subject to attack by

blue- and green-mold and stem-end rot.

Limes picked when over-mature may develop stylar-end breakdown during transit.

Green color is maintained better at lower

temperatures, but pitting (chilling injury)

may occur when limes are held at temperatures below 46oF (8oC).

Recommended loading methods:

• Fiberboard boxes—Load boxes lengthwise

on their bottoms. Most limes are packed in a

fiberboard box containing 10 pounds, but a

few are still shipped in a 4/5-bushel fiberboard box. Load the 4⁄5-bushel boxes in an

airflow pattern (figure 10) or palletized 9

per layer and 6 layers high. See figure 12 for

pallet loading patterns. 

Mangoes

Recommended transport conditions:

• Desired transit temperature:

55oF (13oC)

• Desired relative humidity:

85 to 90 percent

• Highest freezing point:

30.3oF (–0.9oC)

Generally, the best transit temperature for

mangoes is 55oF (13oC). All mangoes are

highly susceptible to chilling injury which is

manifested as a gray scald-like discoloration

of the skin often accompanied by pitting,

uneven ripening, and poor flavor and color

development. Some varieties are susceptible

to chilling injury below 55oF (13oC). Other

varieties can withstand transit temperatures

down to 50oF (10oC) before sustaining chilling injury. Mangoes ripen slowly at 55oF

(13oC). 

Recommended Loading Methods:

• Fiberboard boxes—Load boxes lengthwise

on their bottoms in an airflow pattern with

unobstructed lengthwise air channels (figure

10). Most Florida shippers palletize their

mangoes, and load using the center-load pattern (figure 12b).

Melons (Honeydew, Casaba, 

Crenshaw, Persian)

Recommended transport conditions:

• Desired transit temperature:

45o to 50oF (7o to 10oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

30.5oF (–0.8oC)

Melons are very sensitive to chilling injury

(pitting and physiological breakdown), and

are easily bruised. Temperatures below 45oF

(7oC) may result in sunken areas on the skin

and eventual decay. 
44

NOTE: Research has shown that honeydew

melons may be transported at 36o to 41oF

(2o to 5oC) if they are treated with 1,000

p/m ethylene gas for 24 hours immediately

after harvest and then cooled to these temperatures. For ethylene gas treatments to be

effective, the melons must be above 70oF

(21oC). The gas may be applied before or

after loading for more uniform ripening. 

Precool honeydew melons before loading if

they are extremely hot, over 80oF (27oC).

The amount of precooling will depend on

the initial temperature of the melons, the

amount of intransit ripening desired and the

capacity of the trailer’s refrigeration system.

Many packing sheds ship honeydews at

around 80oF (27oC) to allow some ripening

in transit. 

Honeydews have a relatively low respiration

rate and are not densely packed. Most modern refrigerated trailers should have the

capacity for intransit temperature pull down

provided the melons are loaded at or below

the normal 80oF (27oC) shipping temperature, with good air circulation to all parts of

the load. 

Recommended loading methods:

• Corrugated fiberboard boxes—Most

melon boxes are palletized. Five pallet load

patterns are shown in figure 12. However, if

the melons require intransit ripening, use the

pattern shown in figure 12a to maximize air

circulation in the load. Use an airflow pattern (figure 10) for hand-stacked loads. 

Mushrooms

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 percent

• Highest freezing point:

30.4oF (–0.9oC)

Fresh mushrooms are highly perishable with

a shelf life of about 1 week under optimum

conditions. Prompt precooling after harvest

and close temperature control during transit

are essential. Mushrooms are easily bruised

and should be handled carefully. Moisture

from condensation or other sources should

be avoided. Mushrooms are sensitive to

water and may develop brown spots and

decay rapidly if wet. Fresh mushrooms may

be prepackaged in 8-, 12-, and 16-ounce

(0.23, 0.34, and 0.45 kg) consumer packages, which are then packed in fiberboard

trays. They also may be packed bulk in 10-

pound (4.5 kg) fiberboard trays, or in 3-

pound (1.4 kg) wooden baskets or fiberboard boxes.

Recommended loading methods:

Nearly all mushrooms are palletized for

shipment. See figures 12a and b for pallet

loading patterns.

Okra

Recommended transport conditions:

• Desired transit temperature:

45o to 50oF (7o to 10oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

28.7oF (–1.8oC)

Okra deteriorates rapidly and has a very

high rate of respiration at warm temperatures. Okra has a shelf life of about 10 days.

Do not top-ice, because this will cause water

spotting at all temperatures. At temperatures

below 45oF (7oC), okra is susceptible to

chilling injury which is manifested by surface discoloration, pitting, and decay. Okra

also is easily bruised, and bruised areas will

blacken rapidly.

Recommended loading methods:

• Wirebound crates—Load crates lengthwise

on their bottoms in an airflow pattern (figures 10 and 11).

• Fiberboard boxes—Load boxes lengthwise

on their bottoms in an airflow pattern (figure

10). If palletized, use pallet load patterns

(figure 12).
45

Onions (green), Shallots, and Leeks

Recommended transport conditions: 

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point:

Onions (bunch or spring):

30.4oF (–0.9oC)

Shallots (white leaf bare):

31.6oF (–0.2oC)

Leeks (blanched stalk):

30.7oF (–0.7oC)

• Top-ice and/or package-ice OK

Green onions and shallots are highly perishable and should be precooled soon after harvest. Crushed ice in the package and top-ice

will help to retain moisture and crispness,

and help reduce yellowing. Do not load

leeks with figs or grapes since these products will absorb the leek odor. Odor from

green onions is absorbed by corn, figs,

grapes, mushrooms, and rhubarb.

Recommended loading methods:

• Fiberboard boxes (waxed)—Load boxes

lengthwise or crosswise on their bottoms.

Load with other commodities that require

top-icing and leave space between rows of

boxes or pallet loads for top-ice to fill (figure

16). If top-ice is not used, hand-stack loads

in an airflow pattern (figure 10) to allow

maximum ventilation. Load palletized boxes

in an airflow pattern (figures 12a and 18).

• Wirebound crates—Load crates in the

same way as fiberboard boxes.

Onions (dry bulbs)

Recommended transport conditions:

• Desired transit temperature:

32o-45oF (0o-7oC) storage varieties

45o-60oF (7o-15.5oC) fresh varieties

• Desired relative humidity:

65 to 70 percent

• Highest freezing point:

30.6oF (–0.8oC)

Dry onions store well if held at the proper

temperature and humidity and kept dry after

they are cured. Higher temperatures will

cause sprouting and decay. Onions removed

from cold storage during warm weather tend

to sweat on contact with warm humid air.

Avoid these conditions by minimizing the

time the onions are on an open dock or loading from enclosed docks. Further reduce

condensation by precooling the vehicle

before loading and maintaining adequate air

circulation in the vehicle during transit. Dry

onions are packaged in a variety of ways for

shipment, including 25- and 50-pound (11.3

and 22.7 kg) mesh or plastic bags, 40-pound

(18 kg) fiberboard boxes and various sizes

of consumer-size mesh and plastic bags in

shipping boxes.

Recommended loading methods:

• Open mesh or plastic bags—Load bags

lengthwise or crosswise on floor or pallets.

Load away from the walls and floor in

extremely hot or cold weather to prevent

temperature damage. Wrap with net or strap

loads to secure the onions to the pallet. Center-load the pallets to keep the onions away

from the walls in extremely cold or hot

weather (figure 12b).

• Fiberboard boxes—Load hand-stacked

boxes lengthwise on their bottoms in an airflow pattern (figure 10). Or load the boxes

lengthwise or crosswise on pallets, and load

the pallets off the wall (figure 12b).

Oranges

Recommended transport conditions:

• Desired transit temperature:

Florida and Texas: 32o to 34oF 

(0o to 1oC)

California and Arizona: 38o to 48oF 

(3o to 9oC)

• Desired relative humidity:

85 to 90 percent

• Highest freezing point:

Peel 29.7oF (–1.3oC)

Flesh 30.6oF (–0.8oC)

The preshipment handling of oranges varies

by production area and season. Generally,
46

the fruit is washed, waxed, treated, and

packaged for shipment. Most shippers do

not precool oranges; therefore, the fruit temperature at loading depends on ambient temperature. Oranges are precooled in some

areas, particularly in California. It is important to precool oranges prepackaged in polyethylene or mesh consumer bags and

shipped in master shipping cartons, since the

packaging makes it very difficult to cool in

transit.

California and Arizona oranges shipped at

temperatures below 38oF (3oC) are susceptible to chilling injury and other rind disorders. Oranges from all citrus-producing

areas are subject to blue- and green-mold

rots. In addition, Florida and Texas fruit are

susceptible to stem-end rot. Losses from

decay can be reduced by decay inhibitors,

careful handling to prevent skin breaks, and

proper refrigeration. 

Recommended loading methods:

• Fiberboard boxes—Load boxes lengthwise or crosswise on their bottoms. Load

hand-stacked boxes in an airflow pattern

(figure 10). This pattern allows cooling by

the refrigeration system or by ventilation of

outside air when the ambient temperatures

are reasonably close to the desired transit

temperature. Shipments also may be unitized on pallets or slipsheets. See figure 12

in “Unit or Pallet Loads” for pallet loading

patterns.

• Bins—Some shippers pack oranges in pallet

bins constructed of fiberboard, wood, or wire

mesh. The oranges may be in bulk or in open

mesh bags when packed in the bins. Stack

these bins two-high in the truck. Bin loading

patterns are the same as for pallets (figure 12).

Take care not to block ventilation between the

layers when stacking solid wall bins.

Parsley

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point:

30oF (–1.1oC)

• Top- or package-ice desirable

Parsley keeps well at 32oF (0oC) in combination with high humidity. Like all leafy

vegetables, parsley has a high rate of respiration and its temperature must be lowered

quickly to retard respiration and spoilage.

Usually parsley is hydro- or vacuum-cooled

and top- or package-ice is applied before

shipment to maintain its crispness. It usually

is ordered in small lots and shipped in

mixed loads with other commodities. Parsley is sensitive to ethylene, so do not ship

with ethylene-producing products.

Recommended loading methods:

• Fiberboard boxes (waxed) and wirebound

crates—Load boxes and crates lengthwise

on their bottoms. Load in rows across the

trailer with space divided evenly between

the rows for top-ice to fill (figure 16). For

palletized loads, stack the containers lengthwise or crosswise on the pallets. Leave

space between the pallet rows and walls for

top-ice to fill (figure 12a).

Parsnips

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

98 to 100 percent

• Highest freezing point:

30.4oF (–0.9oC)

• Top- or package-ice desirable

Parsnips have transit and storage requirements similar to carrots. They are topped

after harvest and will keep up to 4 months if

held at 32oF (0oC) and a high relative

humidity. Parsnips tend to shrivel from lack

of moisture.

Recommended loading methods:

• Open mesh or plastic film bags—Parsnips

are usually packaged in plastic film bags

and shipped with ice. Stack bagged
47

parsnips so that when loaded, the parsnips

are in a vertical position. Stack the bags so

that top-ice can infiltrate the load. Bagged

parsnips are often palletized and top-iced.

In this case, use a pallet loading pattern

(figure 12a).

• Fiberboard boxes (waxed)—Hand-stack

boxes lengthwise on their bottoms, in register, in rows across the truck. Divide the

space evenly between the rows for top-ice to

fill (figure 16). When palletized, columnstack the boxes in the lower layers to retain

their strength. Cross-stack the upper layers

to stabilize the pallet load. See figure 12 for

pallet loading patterns.

Peaches and Nectarines

Recommended transport conditions:

• Desired transit temperature:

31o to 32oF (–0.6o to 0oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

30.4oF (–0.9oC)

Peaches and nectarines are relatively tender

fruits and bruise easily. They are usually

harvested and shipped while still firm, so

that physical injury will be minimized during transit and marketing. To delay ripening

and retard decay, promptly hydrocool or

cool with forced air to the desired transit

temperature before loading.

Recommended loading methods:

• Corrugated fiberboard boxes—Load

boxes lengthwise on their bottoms. Boxes

are usually volume-filled with 25 to 30

pounds (11.3 to 17.2 kg) of fruit. Most

shippers unitize their fruit on disposable

wooden pallets. 

• Wooden or fiberboard lugs—Load lugs

lengthwise on their bottoms. The fruit is

often packed in plastic trays, in either one or

two layers, which are then packed in the

lugs. The lugs are palletized. 

If not precooled, load hand-stacked containers in an airflow pattern (figure 10). Centerload palletized containers (figure 12b).

Pears

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

29.2oF (–1.6oC)

Precool pears as soon after harvest as possible to protect their shelf life. The storage life

of pears ranges from 2 to 8 months, depending on variety. Extensive warming of pears

starts the ripening process which cannot be

reversed. Therefore, transport pears as close

to the storage temperature as possible.

Recommended loading methods:

• Corrugated fiberboard boxes—Fiberboard

boxes may be volume-filled, place-packed,

or tight-filled (vibration settled) with the

cover tightly secured with strapping material or staples. The boxes are usually unitized

on disposable wooden pallets and secured

by straps or netting. Load patterns for pallets are shown in figure 12. For handstacked loads, use a tight loading pattern if

the pears are thoroughly precooled. If the

pears are not precooled to near the desired

transit temperature, load in an airflow pattern (figure 10).

Peas (green and snow peas in pods)

Recommended transport conditions:

• Desired transport temperature:

32oF (0oC)

• Desired relative humidity:

95 to 98 percent 

• Highest freezing point:

Pods: 30.9oF (–0.6oC)

Shelled peas: 29.9oF (–1.2oC)

• Top- or package-ice required
48

Fresh green peas are extremely perishable

and require the utmost care to keep them in

salable condition. To slow the changing of

sugar to starch, lower and hold the temperature of the peas to near 32oF (0oC) immediately after harvest by vacuum- or hydrocooling. Top-ice after loading to help maintain a

low temperature and the fresh appearance of

the pods. With less-than-truckload shipments

of peas and where top-icing is not feasible,

pack the peas with crushed ice. Peas are ethylene-sensitive, so do not ship in mixed

loads with ethylene-producing products.

Recommended loading methods:

• Wirebound crates—Hand-stack crates

lengthwise or crosswise on their bottoms.

Keep rows aligned, with space divided evenly

in between for top-ice to fill (figure 16).

When crates are palletized, use an off-wall

pattern (figures 12a and b) which allows maximum air circulation or top-ice infiltration. 

• Fiberboard boxes (waxed)—Pack peas in

waxed fiberboard containers that are well ventilated, with holes on all faces. Pack crushed

ice with the peas. Load hand-stack boxes and

pallets the same as wirebound crates.

Peppers (sweet)

• Desired transit temperature:

45o to 55oF (7o to 13oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

30.7oF (–0.7oC)

Mature-green peppers held at temperatures

below 45oF (7oC) will incur chilling injury.

Peppers stored at chilling temperatures

develop pitting, scald, and various decays. At

temperatures above 55oF (13oC) peppers can

decay quite rapidly. Peppers are sensitive to

ethylene, which will hasten ripening, so do

not ship with ethylene-producing products.

Recommended loading methods:

• Fiberboard boxes—Load boxes lengthwise

on their bottoms. Hand-stack boxes in an

airflow pattern (figure 10). Many shipments

of peppers are palletized. See figure 12 for

pallet loading patterns.

Pineapples

Recommended transport conditions:

• Desired transit temperatures:

Mature-green fruit, 50o to 55oF 

(10o to 13oC)

Ripe fruit, 45oF (7oC)

• Desired relative humidity:

85 to 90 percent

• Highest freezing point:

30.0oF (–1.1oC)

Mature-green pineapples are susceptible to

chilling injury if exposed to temperatures

below 50oF (10oC). Symptoms of chilling

injury are impaired ripening, brown or dull

shell color, water soaked flesh, wilting of the

crown, green spotting, and failure to develop

a good flavor. Chilled fruit is particularly

subject to decay if not kept refrigerated.

Recommended loading methods:

• Fiberboard boxes—Load boxes lengthwise

or crosswise on their bottoms. Boxes often

have fiberboard inserts placed between individual fruit to prevent bruising during transit. In extremely cold or hot weather, load

boxes in an offset-by-layers pattern (figure

7a). This will reduce product contact with

the vehicle walls and possible chilling or

freezing injury, especially if the walls are

flat. Center-load pallets away from the walls

in extremely cold weather for the same reason (figure 12b).

Plums and Fresh Prunes

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

30.5oF (–0.8oC)

Thoroughly precool plums and fresh prunes

soon after harvest. Generally, plums and
49

prunes are packed and placed in cold-storage

rooms for precooling before shipment. Handle

carefully, because bruising and skin breaks

may result in decay and loss of quality.

Recommended loading method:

• Corrugated fiberboard boxes—Load boxes

lengthwise or crosswise on their bottoms. A

considerable amount of this fruit is tightfilled (vibration-settled in the boxes with the

cover tightly fastened) to reduce fruit bouncing and rotation in the boxes from highway

vibration. Fruit movement within the boxes

results in discolored rings in the skin around

individual fruit, known as “roller bruising.”

Also, some fruit is tray-packed in fiberboard

boxes. The boxes then are unitized on disposable wooden pallets and secured with

straps or netting material (figure 14). Figure

12 shows pallet loading patterns.

Potatoes

Recommended transport conditions:

• Desired transport temperature:

Early crop—for table, 50o to 60oF 

(10o to 16oC)

—for chipping, 65o to 70oF 

(18o to 21oC)

Late crop—for table, 40o to 50oF 

(4o to 10oC)

—for chipping, 50o to 60oF 

(10o to 16oC)

• Desired relative humidity:

90 percent

• Highest freezing point:

30.9oF (–0.6oC)

Ventilation, heating, or cooling may be

required for potatoes in transit depending on

the time of year and outside temperature

conditions.

Early crop, or new, potatoes are harvested

and shipped from the southern States during

the winter, spring, and summer. Because

these potatoes are shipped before their skin

has had time to set or mature, they are easily

skinned and bruised. Broken skins open the

way for decay organisms and tissue browning at the surface and lower the market value

of the product. Potatoes, fortunately, have the

inherent ability to seal skin breaks by producing suberin and wound periderm, which

are essentially new skin. This self-healing

process proceeds best at a high humidity and

temperatures of 60o to 70oF (16o to 21oC). If

newly harvested potatoes are to be in transit

for more than 48 hours, the lower portion of

this temperature range is recommended.

As a rule, early crop potatoes may be

shipped satisfactorily under ventilation. Ventilation aids drying when weather permits.

Load in an airflow pattern to ensure full

ventilation of potatoes packed in fiberboard

boxes (figure 10).

Late crop potatoes are harvested during the

summer and fall. They are allowed a longer

time to mature before being dug. Therefore,

their skins are less prone to injury from handling. Because of their tougher skins and

less skinning, they do not need the higher

temperature and humidity for healing

required by early crop potatoes.

Most late crop potatoes are grown and

stored in the northern States. They are

shipped from storage in the late fall, winter,

and early spring. Since many shipments

move through areas with subfreezing temperatures, heat is often needed when transporting late crop potatoes. Operate fans with

the heating system to circulate the warmed

air around the load. 

CAUTION: Take care to vent all direct

combustion heaters.

Freezing damage is most likely in bags of

potatoes loaded directly on the truck floor

and against the bottom sidewalls. Cushioning or padding material on the floor will

help insulate the product in the bottom layers, and protect against bruising from overhead weight. However, do not use any material, such as straw, that will fill the floor

grooves, because it will block warm-air circulation under the load. Several types of

suitable floor padding materials are available from commercial sources. Loading

potatoes on wood pallets with the stringers

running lengthwise also provides a means of

protecting the potatoes from freezing at

floor level by allowing circulating air under

the load.
50

Ventilate loads of late crop potatoes when

outside temperatures range between 40o to

50oF (4o to 10oC) by opening the vent

doors. At temperatures below or above this

range, only open vent doors slightly to avoid

oxygen starvation of the load.

Recommended loading methods:

• Burlap and master bags—Most potatoes

are packed in consumer bags of plastic film

holding 5 or 10 pounds (2.3 or 4.5 kg).

These, in turn, are packed in polyethylene or

paper master bags holding 50 pounds (22.7

kg) and palletized. Research has found that

potatoes incur the most loading-related bruising when bags or boxes are dropped on hard

floor or pallet surfaces. Significant increases

in bruising damage were found when the

drop heights exceeded 30 inches (76 cm). 

Center-load pallets (figure 12b) in extreme

cold weather to keep the potatoes away from

the walls and prevent freezing or chill damage. Load hand-stacked bags in a pyramid

pattern (figure 7b) to reduce wall contact.

• Corrugated fiberboard boxes—Stack boxes

lengthwise or crosswise on their bottoms on

the floor, or unitize on pallets. Hand-stack

boxes of new potatoes in an airflow pattern

(figure 10c) to allow intransit drying. Load

boxes of potatoes shipped from storage in

winter in an offset-by-layers pattern (figure

7a) to reduce contact of potatoes with the

walls and chance of freezing. Center-load palletized boxes (figure 12b) for the same reason.

• Bulk potatoes for chipping—Most potatoes for chipping are shipped from storage

in bulk loads. Always load and transport the

potatoes at the same or slightly warmer

temperature than the storage temperature,

but never at colder temperatures. Handle the

potatoes as gently as possible. Rough handling and improper temperatures may cause

adverse chemical reactions which may

increase the sugar content of the potatoes.

This subsequently results in undesirable

dark-colored chips. Truckers should carry

an accurate thermometer for checking pulp

temperatures of the potatoes. Bulk chipping

potatoes usually are loaded with a bin-piler

conveyor with a telescoping boom. They

are unloaded with an industrial truck or by

gravity flow. 

Construct bulkheads of plywood or place

bags of potatoes 2 to 4 feet (0.6 to 1.2 m)

from the rear doors of the trailers to contain

the loose potatoes. Place heaters in this open

space, when required. 

Chipping potatoes shipped from far northern

States in the winter require heating. Temperature controlled semi-trailers are preferred

and predominantly used. If heaters are used,

operate the fans at all times to circulate the

heated air over and under the load. 

A buildup of carbon dioxide (CO2) and

depletion of oxygen (O2) may also result in

off-colored chips. Therefore, allow a small

amount of outside air to ventilate to the

chipping potatoes at all times. Operate the

fan to circulate fresh air to all parts of the

load. Chipping potatoes should be processed

as soon as possible after unloading.

Radishes

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point:

30.7oF (–0.7oC)

• Top- or package-ice OK

Precool radishes to remove field heat and

preserve natural crispness. Most radishes are

topped and packed in consumer-size plasticfilm packages which are shipped in waxed,

corrugated fiberboard boxes. Some radishes

are shipped with their tops on and to keep

them fresh, these radishes must have top-ice

or package-ice placed in the containers.

Topped radishes packed in consumer bags

keep well in transit and storage for several

weeks, provided the recommended temperature and humidity are maintained. Black

spotting is a major market disease of radishes, but temperatures below 50oF (10oC) control it effectively.

Recommended loading methods:

• Waxed fiberboard boxes (consumer pack-
51

ages)—If shipping a straight load of radishes, hand-stack boxes in an airflow pattern

(figure 10) to allow uniform circulation of

refrigerated air throughout the load.

• Wirebound crates or fiberboard boxes

(bunches with tops)—Load crates or boxes

lengthwise on their bottoms. Keep rows

aligned, evenly dividing the space between

them for top-ice to fill (figure 16). 

• Polyethylene bags (bulk radishes)—

Bagged radishes are usually shipped stacked

on pallets. See figure 12 for pallet loading

patterns. For top-iced loads, use the load

pattern in figure 12a which leaves space

between the pallet rows and the walls for

top-ice to fill. 

Raspberries

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

black—30.0oF (–1.1oC)

red—30.9oF (–0.6oC)

Fresh raspberries soften and decay rapidly.

Under the very best conditions their market

life is 7 to 10 days. Transcontinental truck

shipments of red raspberries from California

are common. These shipments are usually

palletized and in mixed loads with strawberries, which have similar packaging and transit requirements. Raspberries are subject to

various types of mold, which can be controlled most effectively by rapidly precooling and holding the berries at the desired

32oF (0oC) temperature immediately after

harvest. For additional protection against

decay and ripening during transit, major

shippers enclose the pallet loads of berries

in air tight plastic bags and inject an atmosphere modified with 10 to 20 percent carbon

dioxide (CO2). 

Recommended loading method:

• Corrugated fiberboard trays—Load trays

lengthwise on bottoms. Trays of berries usually are palletized to minimize handling.

Strap the trays securely to the pallets to minimize bouncing and rotating of the berries

from highway shock and vibration, a major

cause of physical damage to berries during

transit. Center-load the pallets and brace

away from the walls so that air can circulate

between the walls and the product (figure

12b). 

Rhubarb

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point, stalks:

30.3oF (–0.9oC)

Keep fresh rhubarb at 32oF (0oC) and at a

high humidity to prevent wilting and shriveling. Bunches or loose stalks of rhubarb are

usually wrapped in polyethylene film liners

before packing in shipping boxes to prevent

moisture loss. Do not seal the liners, and

ensure the boxes or crates are well vented to

allow refrigerated air to remove respiration

heat and prevent mold development.

Recommended loading methods:

• Fiberboard boxes—Load boxes lengthwise

or crosswise on pallets. Load hand-stacked

boxes lengthwise on their bottoms in an airflow pattern (figure 10). See figure 12 for

pallet loading patterns.

Romaine Lettuce

Recommended transport conditions:

• Recommended transit temperature:

32oF (0oC)

• Recommended relative humidity:

95 percent

• Highest freezing point:

31.7oF (–0.2oC) 

Romaine is a highly perishable, leafy vegetable requiring maximum refrigeration dur-
52

ing transit. Vacuum-cool or hydrocool

before shipment, depending on the shipper’s

facilities. Romaine is often shipped in mixed

loads, because most orders are for less-thantruckload lots. It is packed both loose and in

plastic bags in fiberboard boxes. Romaine is

sensitive to ethylene gas, so do not ship with

ethylene-producing products.

Recommended loading methods:

• Fiberboard boxes (waxed)—Load boxes

lengthwise on their bottoms. Load handstacked boxes in an airflow pattern (figure

10). Center-load palletized boxes, or use an

airflow pattern to keep the product away

from the walls of the vehicle (figures 12a

and b).

Salad Mixes

Recommended transport conditions:

• Recommended transit temperature:

33oF (0.6oC)

• Recommended relative humidity:

90 to 95 percent

• Highest freezing point:

Varies by commodity components (refer

to individual commodity)

Prepackaged salad mixes are one of the

fastest growing segments of the produce

industry. Salad mixes may contain a wide

variety of vegetables, but the primary components are usually lettuce, cabbage, and

other leafy greens. The mixes are usually

vacuum-packaged in plastic film bags and

shipped in fiberboard boxes. A number of

shippers also inject a mixture of gases or

modified atmosphere into the film package

which is custom-formulated to extend the

shelf life of the particular mix of vegetables

in the salad. To obtain a maximum shelf life

of 10 to 14 days for salad mixes, maintain

the desired transit temperature. Also, do not

puncture the film bags during handling,

which may allow the introduction of ethylene gas and result in russeting and yellowing of the salad components. 

Recommended loading methods:

• Fiberboard boxes—Load boxes lengthwise

or crosswise on pallets. Secure the boxes to

the pallets to prevent handling damage to

the bags and salad leaves, and use an offwall loading pattern (figures 12a and b).

Load hand-stacked boxes in an airflow pattern (figure 10).

Spinach

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

95 to 100 percent

• Highest freezing point:

31.5oF (–0.3oC)

• Top-ice and/or package-ice desired

Fresh spinach is delicate and highly perishable. Handle carefully to prevent damage

to the leaves which presents a potential

point for disease entry. Precool fresh

spinach immediately after harvest, hold

near 32oF (0oC), and pack with ice to prevent wilting and preserve its shelf life of

about 10 to 14 days. Spinach is sensitive to

ethylene, so do not ship with ethylene-producing products.

Recommended loading methods:

• Wirebound crates or waxed fiberboard

boxes—When top-iced, load hand-stacked

crates or boxes lengthwise on their bottoms

in straight rows. Divide space evenly

between the rows for top-ice to fill (figure

16). Stack waxed fiberboard boxes directly

on top of each other so melt-water can run

down through the stack. If not top-iced, load

crates or boxes in an airflow pattern (figures

10 and 11). 

• Fiberboard boxes—Spinach is often

packed in plastic film consumer packs, and

then in fiberboard boxes. For hand-stacked

boxes, load in an airflow pattern (figure 10).

Stack palletized boxes of consumer packs in

register, and secure with strapping to prevent bruising of the tender leaves. Figures

12a and b show the recommended pallet

loading patterns. 
53

Squash and Pumpkins

Recommended transport conditions:

Winter squash (Hubbard and acorn) and

pumpkins

• Desired transit temperature:

50o to 55oF (10o to 13oC)

• Desired relative humidity:

50 to 70 percent

• Highest freezing point:

30.5oF (–0.8oC)

Summer squash (yellow crookneck, straightneck, and zucchini)

• Desired transit temperature

41o to 50oF (5o to 10oC)

• Desired relative humidity

95 percent

• Highest freezing point:

31.1oF (–0.5oC)

After harvest, allow winter squash and

pumpkins to cure at temperatures between

80o and 85oF (27o to 29oC) for 10 to 20 days

to allow healing of mechanical cuts. Cured

squash have a storage life of 2 to 6 months.

However, they are subject to chilling injury,

so do not keep or ship them at temperatures

below 50oF (10oC) for any length of time.

They also require low humidity.

Summer squash are harvested and shipped at

an immature stage. They are more perishable than winter squash. Their storage life is

shorter, and they require lower temperatures

and higher humidity during transit. The skin

of summer squash is very tender and easily

wounded during handling. Summer squash

is chilling-sensitive but can withstand 32o to

40oF (0o to 4oC) temperatures for up to 2

days with little danger of chilling injury.

Recommended loading methods:

• Wirebound crates—Load crates of summer

squash lengthwise on their bottoms in an airflow pattern (figure 10). Crates of winter

squash may be tightly stacked either lengthwise or crosswise on bottoms. Stack wirebound crates in vertical alignment and never

allow them to cross over each other, because

they are not designed to bear overhead

weight on their sidewalls. When palletized,

stack the crates in vertical alignment and

strap securely to the pallet. Center-load the

pallets away from the walls (figure 12b),

unless the walls are ribbed to allow air circulation. 

• Fiberboard boxes—Load fiberboard boxes

of winter squash crosswise or lengthwise on

their bottoms. Load hand-stacked boxes of

summer squash in an airflow pattern (figure

10). Center-load palletized boxes (figure 12b).

• Bulk-bins—Pumpkins often are shipped in

bulk bins. If the bins are double stacked,

take care not to over fill the bins on the bottom layer, or pumpkins will be crushed.

Strawberries

Recommended transport conditions:

• Desired transit temperature:

32oF (0oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

30.6oF (–0.8oC)

Strawberries are extremely perishable and

rarely keep more than 10 days under ideal

conditions. Temperatures near 32oF (0oC)

are essential to control decay and ripening.

Precool strawberries immediately after harvest to as close to 32oF (0oC) as possible.

Most California shippers palletize their

strawberries. In some cases, they place a

sealed plastic bag around each pallet load

unit, filled with a modified atmosphere containing about 14 percent CO2 gas to assist in

retarding decay and ripening.

Strawberries are highly susceptible to decay

by fungal rots and molds. Ship only sound

fruit, because decay fungi are easily spread

throughout the shipping container. Handle

strawberries very carefully, since they are

easily bruised. Bruised berries are very susceptible to decay.

Recommended loading methods:
54

• Open-top fiberboard tray boxes—Nearly

all strawberries are shipped in tray boxes

which are designed to interlock by wires or

tabs when stacked in register. Load handstacked trays in rows lengthwise on their

bottoms and stabilize every fourth layer with

wood strips placed horizontally across the

truck.

Secure palletized loads with strapping to

prevent the trays of berries from bouncing.

Highway shock and vibration is a major

cause of intransit abrasion and bruising.

Take extreme care to load and brace the pallets to prevent intransit shifting. Center-load

the pallets off the walls to prevent heat conduction from the trailer walls to the fruit

(figures 12a and 17).

Sweet Potatoes

Recommended transport conditions:

• Desired transit temperature:

55o to 60oF (13o to 16oC)

• Desired relative humidity:

85 to 90 percent

• Highest freezing point:

29.7oF (–1.3oC)

Sweet potatoes are harvested in late summer

or early fall. Some are shipped immediately

to market in the “green” state, noncured.

The rest are cured and shipped from storage

throughout the year. They are washed, sorted, and sometimes treated with a decay preventive before being shipped to market.

Also, many shippers wax sweet potatoes and

dye them red.

Uncured sweet potatoes require careful handling to prevent skin breaks and decay.

Cured sweet potatoes are easier to handle.

Sweet potatoes are subject to chilling injury

at temperatures below 50o F (10oC), even if

only for a few hours, which may impair

their appearance, taste and texture. Sprouting may occur at temperatures above 60oF

(16oC), and temperatures above 70oF (21oC)

may cause decay.

Sweet potatoes are predominantly shipped in

fiberboard boxes containing 50 pounds (23

kg); however, some are packed in smaller

fiberboard boxes, and some are packed in

wirebound crates, or bags.

Recommended loading methods:

• Fiberboard boxes—Load boxes lengthwise

on their bottoms. Load hand-stacked boxes

in an airflow pattern (figure 10). See figure

12 for pallet loading patterns.

Tangerines

Recommended transport conditions:

• Desired transit temperature:

40oF (4oC)

• Desired relative humidity

90 to 95 percent

• Highest freezing point:

30.1oF (–1.1oC)

Tangerines are highly perishable. During

marketing they are very susceptible to

decay, particularly green- and blue-mold

rots. Careful handling from tree to table

helps to prevent bruising and skin breaks

that provide ready entrance for decay organisms. Other citrus varieties, such as tangelos

and honey tangerines (Murcott), are thinskinned and need careful handling. Most of

these varieties can be shipped at near 32oF

(0oC) during domestic transit periods of

several days. However, ship Temple oranges

and Orlando tangelos at 40oF (4oC),

because they are susceptible to chilling

injury at lower temperatures. Precool tangerines before shipping.

Recommended loading methods:

• Fiberboard boxes—Load boxes lengthwise

on their bottoms in an airflow pattern (figure

10). See figure 12 for pallet loading patterns.

• Wirebound crates—Load crates lengthwise

on their bottoms in an airflow pattern (figures 10 and 11).

Tomatoes (mature-green)

Recommended transport conditions:

• Desired transit temperature:
55

55o to 70oF (13o to 21oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

31oF (–0.6o)

Mature-green tomatoes are harvested in the

green stage and are washed in chlorinated

water, graded, and packed immediately

after harvest. After packing, some tomatoes are placed in ethylene degreening

rooms at 70oF (21oC) for about 48 to 72

hours to initiate ripening. Most go through

this process at wholesale marketing facilities. After ethylene degreening, the best

temperatures for transport and storage of

tomatoes are between 55o and 70oF (13o to

21oC). At temperatures lower than 50oF

(10oC) mature-green tomatoes may incur

chilling injury and be of poor internal

quality. At temperatures above 70oF

(21oC), tomatoes may ripen too rapidly

and decay extensively.

Recommended loading methods:

• Fiberboard boxes—Most tomatoes are

shipped in partial telescope fiberboard

boxes. Load hand-stacked boxes in an airflow pattern (figure 10). Most shippers palletize their shipments. See figure 12 for pallet loading patterns.

Tomatoes (pink)

Recommended transport conditions:

• Desired transit temperature:

46o to 50oF (7o to 10oC)

• Desired relative humidity:

90 to 95 percent

• Highest freezing point:

31.1oF (–0.5oC)

Tomatoes harvested soon after their color

begins to redden are called pink, or “vineripened” tomatoes. Pink tomatoes are not

as sensitive to chilling injury as mature

green fruit. Handle pink tomatoes carefully

to avoid mechanical injury. External and

internal bruising may affect appearance,

color, or flavor. Shipping temperatures for

pink tomatoes will depend largely on the

number of days in transit and the degree of

ripeness which the receiver may desire.

Many shippers precool their pink tomatoes

to the transit temperature which will maintain the desired color level. Pink tomatoes

are generally packed in fiberboard boxes

with two or three layers per box. Some

shippers pack their pink tomatoes in pulp

or foam trays.

Recommended loading methods:

• Fiberboard boxes—Load hand-stacked

boxes lengthwise on bottoms in an airflow

pattern (figure 10). Most shippers palletize

their tomato loads. See figure 12 for pallet

loading patterns.

Watermelons

Recommended transport conditions:

• Recommended transit temperature:

50o to 60oF (10o to 16oC)

• Recommended relative humidity:

90 percent

• Highest freezing point:

31.3oF (–0.4oC)

Watermelons are generally shipped in bulk

under ventilated conditions. In moderate

weather, refrigeration normally is not

required for transit periods of a few days.

Improve flavor and intensify color by holding watermelons up to 7 days at room temperature. However, if the melons are to be in

transit for longer than 1 week, they should be

refrigerated in the 50o to 60oF (10o to 16oC)

range. At temperatures between 32o to 50oF

(0o to 10oC), watermelons are subject to

chilling injury which may include pitting,

off-flavors, and color loss. Watermelons also

are sensitive to ethylene, so do not ship with

ethylene-producing products. Serious transit

losses may result when watermelons are

cracked and bruised by improper handling

and loading. Bruising makes the melons

more susceptible to decay. When loading

bulk melons, place cushioning material on

the trailer floor to protect them. Various

types of cushioning materials are available,

such as excelsior, polystyrene foam, straw,

etc. Although straw is commonly used, it is

not recommended in trailers with floor
56

grooves because it blocks air circulation

under the load and fills desired spaces

between the melons. 

Recommended loading methods:

• Bulk—The greater percentage of watermelons are shipped in bulk. Load both the longtype and round-type melons in rows parallel

to the sidewalls of the trailer. Even-numbered layers will hold one less melon than

odd numbered-layers. The number of layers

in a particular load will depend on the

weight of the trailer, highway weight limitations, and the quality of the watermelons.

• Fiberboard boxes—Fiberboard boxes may

contain two to six watermelons. Load the

boxes lengthwise on their bottoms, one box

directly on top of another, and either 4 or 5

boxes wide, depending on size of the trailer

and boxes. Divide slack space across the

width of the trailer evenly between the rows,

providing lengthwise air channels between

each row. Fiberboard boxes of watermelons

are frequently palletized. See figure 12 for

pallet loading patterns.

• Bulk bins—Bulk bins of watermelons on

pallets may weigh from 800 to 1200 pounds

(363 to 554 kg). Stack the bins two-high in
57

the trailer. To prevent crushing, put fewer

melons in the lower bin. See figure 12 for

pallet loading patterns. 

Damage claims for canned goods cost carriers millions of dollars annually. There are

two major causes of damage to canned

foods during distribution—mechanical and

temperature. Improper handling causes

mechanical damage, dented or broken cans

and bottles, and is responsible for the greatest percentage of claims. A smaller percentage of the claims results from improper temperature conditions, which cause rusting of

the cans or freezing of the contents.

Damage is caused to canned goods in many

ways, such as:

• poorly sealed cases;

• careless handling of cans during processing and warehousing;

• improper stacking on pallets;

• careless handling with mechanical-lift

trucks;

• loose or slack loading in the vehicle;

• improper bracing, wrapping, or strapping;

and

• failure to brace remainder of the load after

a dropoff.

Poorly sealed cases may let cans or jars fall

out during handling. Check cases of canned

goods periodically during loading for indications of damage. Do not accept a heavily

damaged load.

Currently, most canned goods are unitized

for warehousing and shipment. Mishandling

of pallets with mechanical-lift trucks and

poor stacking of cases on the pallets are

important sources of damage. Stack the

cases so that they are flush with the edges of

the pallet. If the cases overlap the edges of

the pallet, lift trucks may push against the

canned goods instead of the pallet during

handling. If there is a space between the outside edges of the stack and the pallet edges,

considerable slack space may be left

between the pallets after they are loaded in

the vehicle. This may allow the cases to

shift during transit. 

Another source of damage is loose pallet

boards. A loose edge board will allow pressure to be exerted on the cases in the bottom

layer, when the pallet is lifted with a fork lift

truck. Keep pallets in good repair at all

times.

A large percentage of the unit loads of

canned goods are stretch- or shrink-wrapped

with plastic film before shipment. This

assures integrity of the pallet loads and

reduces damage claims.

Tight loading is important, whether the shipment is unitized or hand-loaded. Any slack

space that lets the cases shift or fall may

result in damaged goods. Load the cases or

pallet units snugly together, and brace the

end of the last stack. In a split shipment,

brace and block the end of the last stack

before moving to the next dropoff. Use

spacers or inflatable dunnage to fill out

crosswise slack. All pallets or stacks should

be the same height, unless precautions are

taken by bracing or otherwise, to prevent the

uneven top layer from shifting.

Truck drivers cannot control all damage that

Canned Foods
58

may occur before and during loading. However, they can reduce the chances of being

blamed for damage beyond their control by

being alert for damaged goods and not

accepting them. They also can control the

damage by closely supervising the loading

of their vehicles. A good slogan for haulers

of canned goods is, “The only right load is a

tight load.”

The most frequent type of temperature damage to canned foods is rusting of tin cans.

Rusting is caused by condensation on cans

removed from a low-temperature environment to one with a higher temperature. Condensation causes rust spots on the cans and

wrinkling of the labels and may make the

product unmarketable. Also, after a period

of storage, the rust spots may pinhole the

cans with leaks and allow the product to

spoil. To prevent rust-causing condensation,

do not unload canned foods in warm warehouse areas which have previously been

subjected to low temperatures, until they

have had time to warm up to 50oF (10oC) or

above.

Freezing is not likely to damage the canned

food product itself. However, freezing a

canned product may endanger the container

integrity or break a glass container. To protect canned food containers against freezing

damage during transit through areas of

intense cold, apply thermostatically controlled heat to keep the product from freezing. See table 4 for the freezing points of

some canned foods. 

Extended exposure of canned foods to 90oF

(32oC) or above temperatures is detrimental

to product quality. In some cases, exposure
59

Table 4. Freezing Temperature of Selected Canned Foods

Freezing

Point

Product oF oC

Applesauce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.6 (–2.4)

Asparagus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.2 (–1.0)

Beans, green stringless . . . . . . . . . . . . . . . . . . . . . . . . . . 30.3 (–0.9)

Beans, lima . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.6 (–1.3)

Beans, with pork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.8 (–1.8)

Beans, strained . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.6 (–0.8)

Beans, wax, cans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.3 (–0.9)

Beans, wax, glass jars . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.2 (–1.0)

Beets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.4 (–0.9)

Carrots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.3 (–0.9)

Catsup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.4 (–7.0)

Chili sauce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.7 (–4.6)

Corn, creamed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.6 (–1.3)

Corn, in brine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.4 (–1.4)

Corn, vacuum-packed . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.7 (–1.3)

Cranberry sauce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.3 (–8.7)

Grapefruit juice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.2 (–1.0)

Milk, evaporated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.4 (–1.4)

Mushrooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.8 (–1.2)

Peaches, heavy syrup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.6 (–1.9)

Peaches, light syrup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.6 (–2.4)

Pears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.6 (–2.4)

Peas, Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.0 (–0.6)

Peas, sweet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.3 (–1.5)

Pea soup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.7 (–2.4)

Potted meat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26.0 (–3.3)

Pumpkin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.7 (–0.7)

Salmon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.2 (–2.7)

Sardines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.2 (–2.1)

Spiced meat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 (–5.4)

Spinach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.8 (–0.7)

Succotash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.9 (–1.2)

Sweet potatoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.2 (–1.6)

Tomatoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.8 (–0.7)

Tomato juice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.8 (–1.2)

Tomato soup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.4 (–2.6)

Tuna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26.3 (–3.2)

Vinegar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.7 (–1.8)
60

to these higher temperatures may result in

total product loss through thermophylic

spoilage.

Butter and Margarine

Recommended transport conditions:

• Desired transit temperature:

Butter (fresh), 39oF (4oC)

Butter (frozen), –10oF (–23oC)

Margarine, 35oF (2oC)

• Desired relative humidity:

Butter, 75 to 85 percent

Margarine, 60 to 70 percent

Butter and margarine usually are shipped

from cold storage and are at the desired transit temperature when loaded. They are

packed in fiberboard boxes that provide

some insulation and allow the product to be

exposed to room temperatures for short periods during loading and unloading without

the risk of serious damage. However, during

shipment the products must be refrigerated at

the recommended temperatures to prevent

softening and quality deterioration. Butter

and margarine absorb odors very easily.

Trucks or trailers previously used for hauling

odorous products, such as fish, cabbage, or

onions, should be well cleaned and aired

before being loaded with butter or margarine.

See section II “Cleaning and Sanitation” for

hints on removing odors from trailers.

Recommended loading methods:

• Fiberboard boxes—Load boxes either

crosswise or lengthwise on their bottoms on

pallets or the truck floor. If the products are

at the desired transit temperature when

loaded, stack the boxes as tightly together as

possible to retain that temperature.

In hot weather, take care to prevent heat

conducted through the walls and floor from

melting the product. To prevent this, provide

space for refrigerated air to circulate around

the perimeter of the load. Some vehicles are

equipped with deep channel floors and

ribbed walls for this purpose. If not, attach

spacer strips vertically to the interior sidewalls to provide air space between the product and the walls. For hand-stacked loads

place pallets on the floor with the stringers

running lengthwise to allow air circulation

under the load. Center-load pallets (figure

12b).

Cheeses 

Recommended transport conditions:

• Desired transit temperature:

34o to 40oF (1o to 4oC)

• Desired relative humidity:

65 to 70 percent

• Highest freezing point:

Variable by variety. Also, freezing may

result in textural changes; see text.

Cheeses need to be protected from heat and

cold. Most cheeses tend to “oil off” at 68oF

(20oC) and above. During oiling off, the fat

leaks from the body, and the cheese quickly

becomes rancid.

On the other hand, subjecting some types of

cheeses to freezing temperatures will result

in texture changes that may not be acceptable to consumers. As a general rule, cheese

should not be held at temperatures below

30oF (–1oC) or above 50oF (10oC).

Dairy Products
61

The recommended temperatures for transporting and holding some common types of

cheeses are shown in table 5.

Recommended loading methods:

• See previous entry, “Butter and Margarine.”

Ice Cream

Recommended transport conditions:

• Desired transit temperature:

–20o to –15oF to (–29o to –26oC)

To maintain top quality, ice cream must be

kept at the desired transit or holding temperature. It also is very important to keep the

temperature of ice cream constant during

loading and unloading. Fluctuating temperatures cause the ice crystals in ice cream to

increase in size. Frequent temperature fluctuations will increase the crystal size to the

point where the ice cream is no longer

acceptable to the consumer.

Trucks used for hauling ice cream should be

built specifically for that purpose, or meet

the Refrigerated Transportation Foundation’s

(RTF) combined equipment DF (deep frozen

or –20oF) rating. RTF-certified trailers will

have the equipment rating posted at several

locations on the exterior of the trailer and on

the refrigeration unit (figure 8).

Table 5. Ideal Temperatures for Transporting Common Types of Cheese (from

ASHRAE Handbook—Refrigeration)

Ideal Transit

Cheese Temperature

oF oC

Brick . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 to 34 -1.1 to 1.1

Camembert . . . . . . . . . . . . . . . . . . . . . . . . . . 30 to 34 -1.1 to 1.1

Cheddar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 to 34 -1.1 to 1.1

Cottage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 to 34 -1.1 to 1.1

Cream . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 34 0.0 to 1.1

Limburger . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 to 34 -1.1 to 1.1

Neufchatel . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 34 0.0 to 1.1

Process American . . . . . . . . . . . . . . . . . . . . . 40 to 45 4.4 to 7.2

Process brick . . . . . . . . . . . . . . . . . . . . . . . . . 40 to 45 4.4 to 7.2

Process Limburger . . . . . . . . . . . . . . . . . . . . 40 to 45 4.4 to 7.2

Process Swiss . . . . . . . . . . . . . . . . . . . . . . . . 40 to 45 4.4 to 7.2

Roquefort . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 to 34 -1.1 to 1.1

Swiss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 to 34 -1.1 to 1.1

Cheese foods . . . . . . . . . . . . . . . . . . . . . . . . . 40 to 45 4.4 to 7.2
62

Recommended loading methods:

• See “Frozen Foods.”

Meat products are highly perishable, and

growth of microorganisms inherent on meat

carcasses is a major cause of deterioration.

Proper refrigeration is necessary to retard

the growth of these microorganisms and preserve the fresh physical appearance of the

meat products. Dehydration also affects the

appearance and marketability of fresh meat.

Table 6 gives the recommended temperatures and humidities for transporting some

fresh meat, seafood, and processed meat

products.

Fresh meats absorb odors readily, so do not

load in vehicles retaining strong residual

odors from other products. Do not ship

meats in mixed loads with strong odor-producing products, such as fish, apples, or

onions.

Boxed Meats

In the United States, nearly all meat animal

carcasses are broken into wholesale or retail

cuts, film packaged, and packed in corrugated fiberboard boxes before shipment. Most

wholesale beef cuts are vacuum packaged in

plastic film. If not vacuum-packed, cuts are

usually individually wrapped before boxing

or packed in a plastic bag liner inside the

boxes. The packaging materials greatly

reduce the chance of microbial contamination and dehydration of the meat during

transport. However, the insulating effect of

the boxes and packaging film make it imperative that the meat be at the desired transit

temperature when packed and loaded. It will

be difficult for the truck’s refrigeration system to remove any heat remaining in the

meat due to the packaging insulation.

Recommended loading methods:

• Fiberboard boxes—Since meat does not

produce respiration heat, stack the boxes

tightly together, if the meat is at the correct

transit temperature when loaded. The same

principle applies here as applies to frozen

foods. Keep a blanket of cold air circulating

around the load to absorb the heat penetrating the walls and floor of the trailer. If the

trailer does not have ribbed walls, in hot

weather load the boxes in a cross-wise offset

pattern (figure 7a) to reduce contact of the

load with the walls. Use a trailer with a deep

channel floor, or provide pallets or floor

racks with 2 inches (5 cm) or more space for

air circulation under the load. In trucks with

overhead air delivery, leave 4 inches (10

cm) of space between the load and the rear

doors to assure adequate air circulation.

Center-load palletized boxes (figure 12b). 

Carcass Meats

Since carcass meats may not be protected by

packaging, take extra precautions to protect

the carcasses from additional contamination

by unsanitary handling, dirt, and strong

odors. The interior of the vehicle must be

constructed of or coated with materials

approved for contact with meat by the

USDA’s Food Safety and Inspection Service

(FSIS). See section VI, “Regulatory Considerations for Truck Construction Materials,

Cleaning Compounds, and Sanitary Food

Transport.” 

Keep all interior surfaces of the truck in

Fresh and Cured Meat and Fresh Seafood
63

Table 6. Recommended Temperatures and Humidities for Protecting Selected

Fresh, Cured, and Processed Meat and Seafood Products During Transit

(from ASHRAE Refrigeration Handbook)

Relative

Commodity Temperature Humidity

oF oC Percent

Fresh meats:

Beef . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 34 0.0 to 1.1 88 to 92

Lamb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 34 0.0 to 1.1 85 to 90

Pork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 34 0.0 to 1.1 85 to 90

Poultry . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 to 32 –2.2 to 0.0 85 to 90

Rabbits . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 34 0.0 to 1.1 90 to 95

Veal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 34 0.0 to 1.1 90

Cured and processed meats:

Bacon:

Cured, farm style . . . . . . . . . . . . . . . . . . 61 to 64 16.0 to 18.0 85

Cured, packer style . . . . . . . . . . . . . . . . . 34 to 39 1.0 to 4.0 85

Dried beef (chipped) . . . . . . . . . . . . . . . . . 50 to 59 10.0 to 15.0 15

Frankfurters . . . . . . . . . . . . . . . . . . . . . . . . 32 0.0 85

Hams:

Light cure . . . . . . . . . . . . . . . . . . . . . . . . 37 to 41 3.0 to 5.0 80 to 85

Country cure . . . . . . . . . . . . . . . . . . . . . . 50 to 59 10.0 to 15.0 65 to 70

Pork Sausages (links or bulk 

country and Polish) . . . . . . . . . . . . . . . . 32 0.0 85

Fresh fish:

Haddock, Cod, Perch . . . . . . . . . . . . . . . . . 31 to 34 -0.6 to 1.1 95 to 100

Hake, Whiting . . . . . . . . . . . . . . . . . . . . . . 32 to 34 0.0 to 1.1 95 to 100

Halibut . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 to 34 -0.6 to 1.1 95 to 100

Herring:

kippered . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 36 0.0 to 2.2 80 to 90

smoked . . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 36 0.0 to 2.2 80 to 90

Mackerel . . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 34 0.0 to 1.1 95 to 100

Menhaden . . . . . . . . . . . . . . . . . . . . . . . . . 34 to 41 1.1 to 5.0 95 to 100

Salmon . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 to 34 -0.6 to 1.1 95 to 100

Tuna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 to 36 0.0 to 2.2 95 to 100

Shellfish:

Scallop meat . . . . . . . . . . . . . . . . . . . . . . . 32 to 34 0.0 to 1.1 95 to 100

Shrimp . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 to 34 -0.6 to 1.1 95 to 100

Lobster (American) . . . . . . . . . . . . . . . . . . 41 to 50 5.0 to 10.0 In sea water

Oyster, clams

(meat and liquid) . . . . . . . . . . . . . . . . . . 32 to 36 0.0 to 2.2 100

Oyster in shell . . . . . . . . . . . . . . . . . . . . . . 41 to 50 5.0 to 10.0 95 to 100
64

good repair. Broken places in the wall and

floor harbor dirt and are difficult to keep

clean. Replace faulty or missing door gaskets and missing floor-drain caps to prevent

dirt and dust from being sucked in the vehicle as it moves over the highway. Keep meat

hooks and rails free of corrosion or rust that

could work loose and fall on the carcasses. 

Before loading, clean and inspect trucks,

pallets, and meat hooks used for hauling carcasses. The wash water should be at least

180oF (82oC) to reduce the number of

microorganisms present and to dissolve fat

particles adhering to the interior surfaces.

Figure 19. 

Side (a) and end (b)

views of a mixed load of

hanging forequarters

and hindquarters of

beef.

(a)

(b)
65

Any sanitizing agents must be approved for

cleaning meat equipment by the USDA’s

FSIS.

In warm weather, precool trucks hauling

meat carcasses before loading to prevent

moisture from condensing on cold carcasses

as they are loaded from refrigerated storage.

Condensation creates conditions favorable

for the growth of slime-forming microorganisms on the meat. Moisture also will condense on cold carcasses when doors are

opened for delivery stops in warm weather.

If at all possible, all loading and unloading

should be in refrigerated areas.

Recommended loading methods:

There are many methods for loading carcass

meats in trucks. Usually quarters of beef are

hung by metal hooks on overhead rails. The

forequarters are hung with long hooks

inserted through the inside of the rib cavity,

usually between the 4th and 5th ribs about

11 inches from the backbone, so the quarters

will balance and hang straight. Hindquarters

are hung with short hooks, the hook being

inserted through the opening in the gambrel

cord of the shank. Figure 19 shows a load of

hanging beef.

Sometimes, both frozen and fresh meat carcasses are loaded stacked like cordwood on

the floor of the truck, or on pallets which are

in turn loaded on the truck. In these cases,

place clean wrapping paper or plastic film

approved by the FSIS between the truck

floor or pallet base and the meat, and also
66

between the meat and the truck walls.

Frozen foods should be kept at 0oF (–18oC)

or lower from the time they are first frozen

until readied for consumption, according to

the code of “Frozen Food Handling and

Merchandising” available from the Frozen

Food Roundtable. The “Roundtable” represents the major trade associations of the

frozen food industry.

Fluctuating temperatures during distribution

degrade the market quality of frozen foods.

Recooling frozen foods to the thermostat set

point after even a slight temperature rise

causes moisture to migrate from the product

to the colder surfaces of the packaging

materials. This results in product dehydration and undesirable frost buildup inside the

packages. Product quality losses will

increase with the amount of temperature rise

and frequency of recooling. 

Frozen foods thaw between 15oF and 32oF

(–9o and 0oC). Although the changes are not

easily recognized, even at temperatures as

low as 0oF (–18oC), frozen foods may deteriorate from fat oxidation and enzymatic

changes. Certain microorganisms also may

develop at temperatures around 20oF (–7oC)

and above, adding to deterioration and contamination of the food. The higher the temperature, the greater the rate of deterioration.

Ensure that trucks transporting frozen food

are:

• clean and free from dirt, debris, odors, or

any substance that may contaminate the

food; 

• constructed, insulated, and equipped with

adequate refrigeration capacity and air delivery system to continuously maintain a product temperature of 0oF (–18oC) or colder.

(Trailers certified by the Refrigerated Transportation Foundation (RTF) will have a

combined equipment rating of “F” for

frozen foods on the certification plates posted at various locations on the vehicle (see

figure 8); and 

• precooled by setting the thermostat at 0oF

(–18oC) and letting the refrigeration unit

operate for at least one-half hour before

loading, or until a temperature gradient is

established across the insulation. Be sure to

schedule adequate time for precooling in

warm weather. 

Load boxes of frozen foods in a solid block,

avoiding contact with the walls. Ensure that

air refrigerated at or below 0oF (–18oC) circulates around all sides of the load to prevent the transfer of heat through the trailer

to the frozen product (figure 4). Floor channels, floor racks, or pallets 2-1/4 inches (6

cm) or more deep will facilitate air circulation under the load.

Provide at least 4 inches (10 cm) of space

between the load and the rear doors to let air

flow freely around the rear of the load. For

vehicles without ribbed walls, attach vertical

stripping (1 or more inches thick) on the

sidewalls to facilitate air circulation

between the walls and load. Leave at least

10 inches (25 cm) of space between the ceiling and the top of the load for unobstructed

airflow over the load. 

A great deal of frozen food is shipped on

pallets or slipsheets. Center-load pallets (figure 12b), and block or brace the load to keep

Frozen Foods
67

the product from toppling against the walls.

If supplemental or emergency refrigeration

is needed for a frozen food shipment, place

solid carbon dioxide (CO2) in the form of

dry ice or snow on top of the load. Keep the

fans running at low speed to uniformly distribute cool air around the load. 

WARNING: The gas CO2 may cause

asphyxiation. Vent the vehicle properly
before entering. 

Poultry (fresh and hard-chilled)

Recommended transport conditions:

• Desired transit temperatures:

Fresh, 26o to 34oF (-3o to 1oC)

Hard-chilled, 0oF to 26oF (–18o to –3oC)

• Desired relative humidity:

90 to 95 percent

• Average freezing point:

27oF (–3oC)

Fresh poultry is shipped by two methods,

fresh and hard-chilled. After the birds are

dressed, they are chilled to 40oF (4oC) or

lower. At this point they may be packed in

bins, boxes, or crates, with or without ice,

and shipped for further processing or for

immediate retail. Fresh poultry has a relatively short shelf life of a week or so at most. 

Hard-chilled poultry has a shelf life of several weeks if it is cooled to below 26oF 

(-3oC) soon after slaughter. The low temperature assures cell contraction and reduces

tissue weepage. Most hard-chilled poultry is

broken into retail cuts and packaged in foam

trays overwrapped with vapor-proof plastic

film. If the poultry is in good initial condition, additional shelf life may be obtained by

vacuum packaging and gas flushing.

Recommended loading methods:

• Pallets—Most poultry is packed in fiberboard boxes and palletized for shipment.

Ensure that the poultry is at the desired transit temperature when loaded. Secure the

boxes to the pallets with strapping or stretch

film to prevent them from toppling. Center-load the pallets off the walls

(figure 12b).

Shell Eggs

Recommended transport conditions: 

• Desired transit temperature:

40oF to 45oF (4o to 7oC)

• Desired relative humidity:

80 to 85 percent

• Average freezing point:

28.0oF (–2oC)

Shell eggs are fragile and highly perishable.

Even though it is not outwardly visible, egg

quality deteriorates rapidly under poor environmental conditions. 

Thoroughly clean and precool the truck or

trailer to at least 45oF (7oC) before eggs are

loaded. Since eggs absorb odors, ensure that

the vehicle is free of residual odors. Do not

ship eggs in mixed loads, especially not with

citrus fruits, onions, or potatoes.

Because of their perishability and the insulating effect of the fiberboard boxes and cartons in which they are shipped, precool eggs

to their desired transit temperature before

they are loaded. Also, because the boxes are

stacked tightly and may be secured on pallets with stretch film or strapping, there is

little or no cooling air circulating through

the load. Pending Federal legislation will

require that eggs destined for consumer markets be precooled to at least 45oF (7oC)

prior to loading and kept at or below this

temperature during transit.

Poultry and Eggs

68
Recommended loading methods:

• 30- and 15-dozen fiberboard boxes—Nearly all eggs shipped in these boxes are palletized, 6 or 12 boxes per layer, on 48- x 40-

inch pallets. However, to maximize use of

space in the trailer, hand-stack one row of

boxes between the pallet rows in the middle

of the trailer as in figure 20. Stack two rows

of boxes between the pallet rows in some

102-inch (2.6 m) wide trailers. 

Because eggs are so fragile, loading and

bracing to prevent cargo movement is

essential. To prevent forward shifting, load

the first pallets snugly against the bulkhead, leaving no lengthwise slack between

the pallets until the end of the load. If the

pallet load heights are uneven, use loadlock bars across the truck at the top layer

to prevent forward or rearward shifting.

Or, in some cases, tape the top one or two

layers of the pallet loads horizontally to

prevent shifting. 

Road shock and vibration are pronounced at

the rear of the truck. Therefore, take extra

care to secure the load in this area. This may

be accomplished by shrink-wrapping the

pallet loads at the rear doors (figure 20) and

by using load-lock bars across the top of the

load. 

• Plastic crates—One-dozen cartons of eggs

are shipped in plastic crates holding 15 or

30 cartons. The cartons are retailed directly

from the crates. The crates fold or nest for

easy return to the egg packing plant. 

• Roll-on/off carts—These carts hold 360 1-

dozen cartons of eggs. They are positioned

on the truck so that the cartons will not slide

or shift off the carts. The carts are braced or

secured with load lock bars. The carts are

69

Figure 20. 

A palletized load of

eggs. Note the stretch

film around the pallet

loads at the rear door

area where road shock

is greatest.

71

rolled off the truck and onto the retail floor

where the eggs are sold off the cart. Empty

carts fold for less space on the return haul.

Estimating Mobile 

Refrigeration Requirements

Estimate the number of Btu’s of heatload

when there is any question as to whether the

truck’s refrigeration system has adequate

capacity. This is particularly important in

hot weather, if the pulp temperature of the

product at loading is considerably above the

desired transit temperature. Shippers who

often receive claims of loss from decay

should make calculations to determine if the

refrigeration capacity is adequate for each

load.

Consider the following three factors in estimating the heatload or amount of refrigeration needed to obtain and maintain the proper temperature during transit:

• Field or sensible heat (Hf) left in the commodity and package

• Heat of respiration (Hr)

• Amount of heat leakage (Hl

) through the

walls of the trailer

Add these three factors to get the total number of Btu’s that must be absorbed by the

refrigeration system.

Field heat (Hf) is the amount of heat that has

to be removed from the product and the containers before the desired transit temperature

is reached. In practice, most products have

not been precooled to the desired transit

temperature. This extra refrigeration requirement must be allowed for. To calculate field

heat load, use the specific heat (Sp.ht.) of

the product (table I-1) and container, the

weight (Wt.) of the product and container,

and the temperature differential (TD) as

shown in the following formula:

Hf = SP.ht. x Wt. x TD = Btu

Determine heat of respiration (Hr) by using

the information in table I-2, which gives the

amount of heat generated by one ton of a

product in 24 hours at different temperatures. To calculate the respiration heat, the

following formula can be used:

Hr = Respiration rate (at average transit temperature) x time (no. of days) x Wt. (tons)

= Btu

Heat leakage (Hl

) through the trailer body is

estimated by determining:

• the coefficient of heat transfer (Ua factor)

of the trailer body;

• the temperature differential between the

thermostat setting and the average expected outside temperature; and 

• the number of hours the product will be in

the vehicle.

The Ua factor for a particular trailer body

depends on many variables—type and thickness of insulation, air leakage, differential

between the outside and inside air temperatures, and others. Therefore, for the purpose of

estimating heat leakage it is impractical to give

the details of all calculations needed to determine the Ua factor. However, the Ua factor

based on a standard method of rating can be

supplied by the manufacturers of some trailers.

If the Ua factor is not readily available, use the

following for general estimation of heatload:

• A factor Ua = 140 Btu/oF/hr. may be used

for a modern 48-foot trailer with 2-1/2

inches of plastic foam sidewall insulation.

• If the trailer has been in service over 3

years, then a factor of 180 Btu/oF/hr.

should be used to account for aging of

deterioration of the insulation and door

Appendix I
72

Table I-1.—Specific Heat Above and Below Freezing of Certain Perishable

Products. (adapted with permission from ASHRAE Handbook—

Refrigeration)

Fruits and Fruits and

vegetables Btu/lb/oF. vegetables Btu/lb/oF.

Above Below Above Below

Apples . . . . . . . . . . . . . . . 0.87 0.45 Limes . . . . . . . . . . . . . . . . .89 .46

Apricots . . . . . . . . . . . . . . .88 .46 Mangoes . . . . . . . . . . . . . . .85 .44

Artichokes (globe) . . . . . . .87 .45 Mushrooms . . . . . . . . . . . 0.93 0.47

Asparagus . . . . . . . . . . . . .94 .48 Nectarines . . . . . . . . . . . . .86 .44

Avocados . . . . . . . . . . . . . .72 .40 Okra . . . . . . . . . . . . . . . . . .92 .46

Bananas . . . . . . . . . . . . . . .80 .42 Onions (dry) . . . . . . . . . . . .90 .46

Beans: Oranges . . . . . . . . . . . . . . .90 .46

Green snap . . . . . . . . . . .91 .47 Parsley . . . . . . . . . . . . . . . .88 .45

Lima . . . . . . . . . . . . . . . .73 .40 Parsnips . . . . . . . . . . . . . . .84 .44

Beets (roots) . . . . . . . . . . . .90 .46 Peaches . . . . . . . . . . . . . . .91 .46

Blackberries . . . . . . . . . . . .88 .46 Pears . . . . . . . . . . . . . . . . . .86 .45

Blueberries . . . . . . . . . . . . .86 .45 Peas (green) . . . . . . . . . . . .79 .42

Broccoli . . . . . . . . . . . . . . .92 .47 Peppers (sweet) . . . . . . . . .94 .47

Brussels sprouts . . . . . . . . .88 .46 Pineapples . . . . . . . . . . . . .88 .45

Cabbage . . . . . . . . . . . . . . .94 .47 Plums and fresh

Cantaloupes . . . . . . . . . . . .93 .48 Prunes . . . . . . . . . . . . . . . .88 .45

Carrots . . . . . . . . . . . . . . .. .90 .46 Potatoes:

Casaba and Early-crop . . . . . . . . . . . .85 .44

Crenshaw Late-crop . . . . . . . . . . . .82 .43

melons . . . . . . . . . . . . . .94 .48 Sweet (see Sweet potatoes)

Cauliflower . . . . . . . . . . . .93 .47 Prunes (see Plums)

Celery . . . . . . . . . . . . . . . . .95 .48 Pumpkins . . . . . . . . . . . . . .92 .47

Cherries (sweet) . . . . . . . . .84 .44 Radishes . . . . . . . . . . . . . . .95 .48

Corn (sweet) . . . . . . . . . . .79 .42 Raspberries:

Cranberries . . . . . . . . . . . . .90 .46 Black . . . . . . . . . . . . . . . .84 .44

Cucumbers . . . . . . . . . . . . .97 .49 Red . . . . . . . . . . . . . . . . .87 .45

Eggplant . . . . . . . . . . . . . . .94 .48 Rhubarb . . . . . . . . . . . . . . .95 .48

Endive and Escarole . . . . .94 .48 Romaine

Figs (fresh) . . . . . . . . . . . . .82 .43 (see Lettuce)

Garlic (dry) . . . . . . . . . . . .69 .40 Spinach . . . . . . . . . . . . . . .94 .48

Gooseberries . . . . . . . . . . .90 .46 Squash:

Grapefruit . . . . . . . . . . . . . .90 .46 Summer . . . . . . . . . . . . .95 .48

Grapes . . . . . . . . . . . . . . . .86 .45 Winter . . . . . . . . . . . . . . .88 .45

Honeydew melons . . . . . . .94 .48 Strawberries . . . . . . . . . . . .92 .47

Kale . . . . . . . . . . . . . . . . . .89 .46 Sweet potatoes . . . . . . . . . .76 .41

Leeks . . . . . . . . . . . . . . . . .88 .46 Tangerines . . . . . . . . . . . . .90 .46

Lemons . . . . . . . . . . . . . . .91 .46 Tomatoes (ripe) . . . . . . . . .95 .48

Lettuce (head) . . . . . . . . . .96 .48 Watermelons . . . . . . . . . . .97 .48
73

seals.

Hl = Ua x TD x time (hours) = Btu

Table I-1.—Specific Heat Above and Below Freezing of Certain Perishable

Products — Continued

Dairy, meat and Dairy, meat and

poultry products Btu/lb/oF. poultry products Btu/lb/oF.

Above Below Above Below

Bacon . . . . . . . . . . . . . . . . .38 .26 Lamb (fresh) . . . . . . . . . . .72 .40

Beef (fresh) . . . . . . . . . . . .77 .41 Milk . . . . . . . . . . . . . . . . . .93 .46

Butter . . . . . . . . . . . . . . . . .36 .25 Oleomargarine . . . . . . . . . .32 .25

Cheese . . . . . . . . . . . . . . . .52 .31 Pork (fresh) . . . . . . . . . . . .53 .31

Eggs (shell) . . . . . . . . . . . .73 .40 Poultry (fresh) . . . . . . . . . .80 .42

Egg solids (whole) . . . . . . .22 .21 Smoked sausage . . . . . . . . .62 .35

Egg yolk solids . . . . . . . . .23 .21 Veal (fresh) . . . . . . . . . . . .74 .40

Ice cream . . . . . . . . . . . . . .70 .39

Hams:

Cured . . . . . . . . . . . . . .. .67 .37

Fresh . . . . . . . . . . . . . . .. .53 .31
74

Table I-2.—Approximate Amount of Respiration Heat Produced by Certain

Fruits and Vegetables at the Temperatures Indicated*

Commodity Btu per ton per 24 hours

32oF 40oF 60oF 70oF 80oF

Apples . . . . . . . . . . . . . 700 1,350 4,900 5,700 —

Apricots . . . . . . . . . . . — 5,050 11,700 20,350 —

Artichokes . . . . . . . . . 7,700 10,450 26,400 40,700 50,050

Asparagus . . . . . . . . . . 9,700 18,050 38,500 48,750 93,250

Avocados . . . . . . . . . . — 5,500 24,050 46,250 60,050 

Bananas (green) . . . . . — — 4,850 7,400 —

Beans:

Green snap . . . . . . . 7,250 10,300 38,100 49,200 —

Lima (in pod) . . . . . 4,450 6,100 24,700 34,300 —

Beets . . . . . . . . . . . . . . 2,700 4,100 7,200 — —

Blackberries . . . . . . . . 4,100 7,950 — 38,350 —

Blueberries . . . . . . . . . 1,400 2,350 10,550 15,300 22,250

Broccoli . . . . . . . . . . . 4,400 21,400 56,500 68,100 158,400

Brussels sprouts . . . . . 4,400 7,700 22,000 28,350 —

Cabbage . . . . . . . . . . 1,200 2,200 4,900 8,450 12,350

Carrots . . . . . . . . . . . 3,300 4,300 8,750 15,500 —

Cauliflower (trimmed) 3,900 4,500 10,100 17,700 24,650

Celery . . . . . . . . . . . . 1,600 2,400 8,200 14,200 —

Cherries:

Sour . . . . . . . . . . . . . 2,100 2,850 8,500 9,800 13,650

Sweet . . . . . . . . . . . . 1,050 2,600 7,700 — —

Corn (sweet) . . . . . . . . 8,950 13,850 35,850 63,700 78,900

Cranberries . . . . . . . . . 650 950 — 3,200 —

Cucumbers . . . . . . . . . — — 5,300 6,850 8,050

Endive and Escarole

(see Leaf lettuce)

Figs (fresh) . . . . . . . . . — 2,650 12,350 16,700 21,000

Gooseberries . . . . . . . . 1,700 2,850 5,950 — —

Grapefruit . . . . . . . . . . — 1,000 3,100 4,250 —

Grapes:

American . . . . . . . . . 600 1,200 3,500 7,200 8,500

European . . . . . . . . . 400 1,000 2,400 — 6,050

Kale (whole leaves) . . 4,700 8,900 30,250 46,900 —

Leeks . . . . . . . . . . . . . 2,900 5,350 21,950 — 24,850

Lemons . . . . . . . . . . . . 700 1,250 3,650 4,850 5,350

Lettuce:

Head . . . . . . . . . . . . 2,500 3,650 8,450 12,200 18,100

Leaf . . . . . . . . . . . . 5,100 6,450 13,800 22,100 32,200

Limes . . . . . . . . . . . . . — 800 1,800 2,800 6,650

Mangoes . . . . . . . . . . . — 3,500 9,900 24,900 26,400
75

Table I-2.—Approximate Amount of Respiration Heat Produced by Certain

Fruits and Vegetables at the Temperatures Indicated — Continued*

Commodity Btu per ton per 24 hours

32oF 40oF 60oF 70oF 80oF

Melons:

Cantaloupes . . . . . . . 1,200 2,050 7,950 12,000 14,700

Honeydew . . . . . . . . — 900 3,050 5,150 6,700

Watermelons . . . . . . — 800 — 4,650 —

Mushrooms . . . . . . . . . 7,900 15,600 46,000 63,800 —

Nectarines (see

Peaches)

Okra . . . . . . . . . . . . . . — 12,250 32,050 57,400 75,900

Onions:

Dry . . . . . . . . . . . . . 650 750 2,400 3,650 6,200

Green . . . . . . . . . . . . 3,600 9,400 17,950 25,800 33,800

Oranges . . . . . . . . . . . . 750 1,200 4,000 6,200 7,150

Parsnips . . . . . . . . . . . 3,000 2,900 8,250 — —

Peaches . . . . . . . . . . . . 1,150 1,700 8,300 17,750 22,350

Pears:

Bartlett . . . . . . . . . . . 1,100 1,650 8,250 11,000 —

Kieffer . . . . . . . . . . . 450 — 3,850 4,750 5,300

Peas:

(green, in the pod) . . 8,500 14,450 41,900 66,750 79,200

Peppers (sweet) . . . . . — 2,900 8,500 9,650 12,100

Pineapples . . . . . . . . . . — 400 3,450 7,050 10,800

Plums (including

fresh Prunes) . . . . . 550 1,450 2,700 4,700 10,900

Potatoes:

Uncured . . . . . . . . . . — 2,600 4,850 6,950 —

Cured . . . . . . . . . . . — 1,250 1,950 2,650 —

Prunes (see Plums)

Radishes (topped) . . . . 1,400 2,100 7,100 11,250 16,400

Raspberries . . . . . . . . . 4,700 7,650 20,200 — —

Rhubarb (without

leaves) . . . . . . . . . . . 2,350 3,200 8,700 10,650 —

Romaine . . . . . . . . . . . — 4,550 9,750 15,100 23,850

Spinach . . . . . . . . . . . . 4,550 10,150 39,350 50,550 —

Squash:

Butternut . . . . . . . . . — — — — 20,650

Yellow straightneck . . . . . . . . . . . 2,700 3,600 18,250 20,050 —

Strawberries . . . . . . . . 3,300 5,450 17,950 32,800 41,800

Sweet potatoes:

Cured . . . . . . . . . . . . — — 4,800 — —

Uncured . . . . . . . . . . — — 6,300 — 14,000
76

Sample Refrigeration

Requirement Calculation1

Assume that a trailer is loaded with 

plums in 30-pound fiberboard boxes:

Load = 1,200 boxes

Net wt. of fruit = 30 pounds per box

Total pounds = 36,000 pounds total (18 tons)

Net wt. of boxes = 2 pounds each

Total pounds = 2,400 pounds total

Sp. ht. of the fruit = 0.88 Btu/lb/oF (table I-1)

Sp. ht. box = 0.44 Btu/lb/oF2

1. Refrigeration needed to remove the remaining field heat in load:

Assumptions:

Loading temperature = T1 = 52oF

Desired transit temperature = T2 = 32oF

Temperature differential = T1 – T2 = TD = 52o – 32o = 20o

then,

Field heat (Hf) = WT. X Sp. ht. X TD

Hf product = 36,000 lb X 0.88 X 20o = 633,600 Btu

Hf boxes = 2,400 lb X 0.40 X 20o = 19,200 Btu

Total field heat = 633,600 + 19,200 = 652,800 Btu

Table I-2.—Approximate Amount of Respiration Heat Produced by Certain

Fruits and Vegetables at the Temperatures Indicated — Continued*

Commodity Btu per ton per 24 hours

32oF 40oF 60oF 70oF 80oF

Tomatoes:

Mature-green . . . . . . — 1,450 4,900 7,650 9,400

Pink . . . . . . . . . . . . . — 1,300 5,850 7,500 9,050

Turnips . . . . . . . . . . . . 1,900 2,150 5,000 5,400 —

Watercress . . . . . . . . . 5,050 10,150 40,700 — —

*Source: USDA Handbook No. 66, 1968
77

2. Transit refrigeration requirement for the heat of respiration:

Assumptions:

If loading temperature = 52o and arrival temperature = 32oF.

then,

Average temperature of product during transit = 40oF.

Transit time = 3 days

then,

Heat of respiration (Hr) = Respiration rate at average transit temperature2

X time (days) X wt. (tons)

Hr = 1,450 X 3 X 18 = 78,300 Btu

3. Refrigeration needed for heat leakage through the trailer body:

Assumptions:

A 48-foot trailer with a Ua factor = 140 Btu/oF/hr.

Average outside air temperature = T1 = 75oF

Thermostat setting = T2 = 34oF4

Temperature differential = TD = T1 - T2 = 75oF - 34oF = 41oF

thus,

Heat leakage (Hl

) = Ua X TD (avg. outside air - thermostat setting) X time (hours) = Btu

Hl = 140 X 41 X 72 = 413,280 Btu

4. To get the total number of Btu’s the refrigeration must remove in 3 days:

Hf + Hr + Hl = 652,800 + 78,300 + 413,280 = 1,144,380 Btu

5. To determine the amount of refrigeration or refrigerant needed:

Mechanical capacity needed = 1,144,380 Btu / 72 hrs. = 15,894 Btu hr.

Ice = total pounds needed for 3-day trip = 1,144,380 Btu / 1445 = 7,947 lb

Liquid nitrogen (N2) = total pounds needed for 3-day trip = 1,144,380 Btu / 1756 = 6,539 lb

1 This calculation does not take into account the following factors: (1) the amount of refrigeration needed to precool

the vehicle body; (2) air inside the vehicle; and (3) refrigeration needed to counteract air leakage around doors and

other places in the body. 2 This figure approximates the specific heat of most wood and fiberboard containers.

3 See table I-2, plums at 40oF 4 For products with a desired transport temperature near 32oF, the thermostat should be set several degrees higher to

decrease the chance of freezing damage.

5 One pound of ice will absorb 144 Btu’s of heat.

6 One pound of liquid nitrogen will absorb approximately 175 Btu’s of heat at temperatures above 32oF. 
78

Appendix II

Load Compatibility Groups1

Group 1

• Apples

• Apricots

• Berries (except cranberries)

• Cherries

• Figs (not with apples, danger of odor transfer to figs; also see group 6a)

• Grapes2 (see groups 2 and 6a)

• Peaches

• Pears

• Persimmons

• Plums and prunes

• Pomegranates

• Quinces

Recommended Transit Conditions:

• Temperature:

32o to 34oF (0o to 1.5oC)

• Relative humidity:

90 to 95 percent

• Atmosphere:

Normally used on berries and cherries only—10 to 20 percent CO2

• Ice:

Never in contact with commodity.

Note: Most members of this group are not compatible with group 6a or 6b because ethylene

production by group 1 can be high, and thus harmful to members of group 6a or 6b.

1 Taken from USDA Marketing Research Report No. 1070, “Compatibility of Fruits and Vegetables During Transport

in Mixed Loads,” by W. J. Lipton and J. M. Harvey, 1977.

2 Grapes: Compatible with other commodities only if the grapes are not fumigated with sulfur dioxide (SO2) in vehicle

and if no chemicals that release SO2 are included in packages.

Group 2

• Avocados

• Bananas
79

• Eggplants (also see group 5)

• Grapefruit3

• Guava

• Limes

• Mangoes

• Muskmelons, other than cantaloupes

Casaba

Crenshaw

Honey Dew

Persian

• Olives, fresh

• Papayas

• Pineapples (not with avocados, danger of avocados’ odor absorption)

• Tomatoes, green

• Tomatoes, pink (also see group 4)

• Watermelons (also see groups 4 and 5)

Recommended Transit Conditions:

• Temperature:

55o to 65oF (13o to 18oC)

• Relative humidity:

85 to 95 percent

• Ice:

Never in contact with commodity

3 Citrus Fruits : Oranges and tangerines—compatibility depends on source. Florida- or Texas-grown oranges are

shipped at 32o to 34oF (0.0o to 1.1oC), but oranges grown in California and Arizona are shipped at 38o to 48oF (3.3o

to 8.8o C).

Group 3

• Cantaloupes

• Cranberries

• Lemons (adjust temperature to other commodity)

• Lychees (also see group 4)

• Oranges

• Tangerines

Recommended Transit Conditions:

• Temperature:

36o to 41oF (2.5o to 5.0oC)

• Relative humidity:

90 to 95 percent; cantaloupes about 95 percent

• Ice:

In contact only with cantaloupes
80

Group 4

• Beans, snap

• Lychees (also see group 3)

• Okra

• Peppers, green (not with beans)

• Peppers, red (if with green peppers, temperature adjusted toward top of range)

• Squash, summer

• Tomatoes, pink (also see group 2)

• Watermelons (also see groups 2 and 5)

Recommended Transit Conditions:

• Temperature:

40o to 45oF (4.5o to 7.5oC)

• Relative humidity:

About 95 percent

• Ice:

Never in contact with commodity

Group 5

• Cucumbers

• Eggplants (also see group 2)

• Ginger (not with eggplants, also see group 7)

• Grapefruit, Florida (after January 1), and Texas

• Potatoes (late crop)

• Pumpkin and squashes, winter

• Watermelons (temperature adjusted for other members of groups; also see groups 2 and 4)

Recommended Transit Conditions:

• Temperature:

40o to 55oF (4.4o to 13oC); ginger not below 55oF

• Relative humidity:

85 to 90 percent

• Ice:

Never in contact with commodity
81

Group 6a

• Artichokes

• Asparagus

• Beets, red

• Carrots

• Endive and escarole

• Figs (also see group 1)

• Grapes (also see group 1)

• Greens

• Leeks (not with figs or grapes)

• Lettuce

• Mushrooms

• Parsley 

• Parsnips

• Peas

• Rhubarb

• Salsify 

• Spinach

• Sweet corn

• Watercress

This group, except for figs, grapes, and mushrooms, is compatible with group 6b.

Recommended Transit Conditions:

• Temperature:

32o to 34oF (0o to 1.1oC)

• Relative humidity:

95 to 100 percent

• Ice:

Never in contact with asparagus, figs, grapes, or mushrooms

Group 6b

• Broccoli

• Brussels sprouts

• Cabbage

• Cauliflower

• Celeriac

• Horseradish

• Kohlrabi

• Onions, green (not with rhubarb, figs, grapes, mushrooms, or sweet corn)

• Radishes

• Rutabagas

• Turnips

This group is compatible with group 6a, except for figs, grapes, and mushrooms.
82

Recommended Transit Conditions:

• Temperature:

32o to 34oF (0o to 1.1oC)

• Relative humidity:

95 to 100 percent

• Ice:

Contact acceptable for all 

Group 7

• Ginger (also see group 5)

• Potatoes, early crop (temperatures adjusted for others)

• Sweet potatoes

Recommended Transit Conditions:

• Temperature:

55o to 65oF (13o to 18oC)

• Relative humidity:

85 to 90 percent

• Ice:

Never in contact with commodity

Group 8

• Garlic

• Onions, dry

Recommended Transit Conditions:

• Temperature:

32o to 34oF (0o to 1.5oC)

• Relative humidity:

65 to 75 percent

• Ice:

Never in contact with commodity
83

Appendix III

Table III-1.—Recommended Protective Services for Perishable Foods During

Transit

Top-ice

Recommended Desired Highest and/or1

Transit Relative Freezing Package-ice

Product Temperature Humidity Point OK

oF oC Percent oF oC

Fresh fruits and

vegetables:

Apples . . . . . . . . . . . 30 - 40 –1.1 - 4.4 90 - 95 30.0 –1.1 No

(depending on

variety)

Apricots . . . . . . . . . . 32 0.0 90 - 95 30.1 –1.1 No

Artichokes (globe) . . 32 0.0 95 - 100 29.9 –1.2 Yes

Asparagus . . . . . . . . 32 - 35 0.0 - 1.7 95 - 100 30.9 –0.6 No

Avocados:

Cold-tolerant

varieties . . . . . . . . 40 4.4 85 - 90 31.5 –0.3 No

Cold-intolerant

varieties . . . . . . . . 55 12.8 85 - 90 31.5 –0.3 No

Bananas . . . . . . . . . . 56 - 58 13.3 - 14.4 90 - 95 30.6 –0.8 No

Beans:

Green or snap . . . . 40 - 45 4.4 - 7.2 95 30.7 –0.7 No

Lima, in pods . . . . 37 - 41 2.8 - 5.0 95 31.0 –0.6 No

Beets . . . . . . . . . . . . 32 0.0 98 - 100 30.3 –0.9 Yes

Beet tops . . . . . . . . . 32 0.0 95 - 100 31.3 –0.4 Yes

Blackberries . . . . . . . 31 - 32 –0.6 - 0.0 90 - 95 30.5 –0.8 No

Blueberries . . . . . . . . 31 - 32 –0.6 - 0.0 90 - 95 29.7 –1.3 No

Broccoli . . . . . . . . . . 32 0.0 95 - 100 30.9 –0.6 Yes

Cabbage . . . . . . . . . . 32 0.0 98 - 100 30.4 –0.9 Yes

Cantaloupes . . . . . . . 36 - 41 2.2 - 5.0 95 29.9 –1.2 Yes 

Carrots . . . . . . . . . . . 32 0.0 98 - 100 29.5 –1.4 Yes

Cauliflower . . . . . . . 32 0.0 90 - 98 30.6 –0.8 Yes

Celery . . . . . . . . . . . . 32 0.0 98 - 100 31.1 –0.5 Yes

Cherries:

Sweet . . . . . . . . . . 30 - 31 –1.1 - –0.6 90 - 95 28.8 –1.8 No

Sour . . . . . . . . . . . 32 0.0 90 - 95 29.0 –1.7 No

Corn (sweet) . . . . . . 32 0.0 95 - 98 30.9 –0.6 Yes

Cranberries . . . . . . . . 36 - 40 2.2 - 4.4 90 - 95 30.4 –0.9 No

Cucumbers . . . . . . . . 50 - 55 10.0 - 12.8 95 31.1 –0.5 No

Eggplants . . . . . . . . . 46 - 54 8.0 - 12.2 90 - 95 30.6 –0.8 No
84

Table III-1.—Recommended Protective Services for Perishable Foods During

Transit — Continued

Top-ice

Recommended Desired Highest and/or1

Transit Relative Freezing Package-ice

Product Temperature Humidity Point OK

oF oC Percent oF oC

Fresh fruits and

vegetables: — Continued

Endive (escarole) . . . 32 0.0 90 - 95 31.9 –0.1 Yes

Garlic (dry) . . . . . . . 32 - 34 0.0 - 1.1 65 - 75 30.5 –0.8 No

Grapefruit:

Arizona and

California . . . . . . . 58 - 60 14.0 - 15.6 85 - 90 30.0 –1.1 No

Florida and Texas . 50 - 60 10.0 - 15.6 85 - 90 30.0 –1.1 No

Grapes:

American type . . . 32 0.0 85 29.7 –1.3 No

European type

(Vinifera) . . . . . . 30 - 31 –1.1 - –0.6 90 - 95 28.1 –2.2 No

Kale . . . . . . . . . . . . . 32 0.0 95 - 100 31.1 –0.5 Yes

Kiwi Fruit . . . . . . . . 32 0.0 90 - 95 29.0 –1.7 No

Lemons . . . . . . . . . . 45 - 55 7.2 - 12.8 85 - 90 29.4 –1.4 No

Lettuce . . . . . . . . . . . 32 0.0 98 - 100 31.7 –0.2 No

Limes . . . . . . . . . . . . 48 - 50 8.9 - 10.0 85 - 90 29.1 –1.6 No

Mangoes . . . . . . . . . . 55 12.8 85 - 90 30.3 –0.9 No

Melons:

Honeydew, Casaba,

Crenshaw, and

Persian . . . . . . . . . 45 - 50 7.2 - 10.0 90 - 95 30.5 –0.8 No

Mushrooms . . . . . . . 32 0.0 95 30.4 –0.9 No

Okra . . . . . . . . . . . . . 45 - 50 7.2 - 10.0 90 - 95 28.7 –1.8 No

Onions (dry) . . . . . . . 32 0.0 65 - 70 30.6 –0.8 No

Onions (green) . . . . . 32 0.0 95 - 100 30.4 –0.9 Yes

Shallots . . . . . . . . . . 32 0.0 95 - 100 31.6 –0.2 Yes

Leeks. . . . . . . . . . . . . 32 0.0 95 - 100 30.7 –0.7 Yes

Oranges2 . . . . . . . . . 32 - 48 0.0 - 8.8 85 - 90 30.6 –0.8 No

 . . . . . . . . . . . . . . . . . (flesh)

 . . . . . . . . . . . . . . . . . 29.7 –1.3

 . . . . . . . . . . . . . . . . . (peel)

Parsley . . . . . . . . . . . 32 0.0 95 - 100 30.0 –1.1 Yes

Parsnips . . . . . . . . . . 32 0.0 98 - 100 30.4 –0.9 Yes

Peaches and

Nectarines . . . . . . . 31 - 32 –0.6 - 0.0 90 - 95 30.4 –0.9 No

Pears3 . . . . . . . . . . . . 32 0.0 90 - 95 29.2 –1.6 No
85

Table III-1.—Recommended Protective Services for Perishable Foods During

Transit — Continued

Top-ice

Recommended Desired Highest and/or1

Transit Relative Freezing Package-ice

Product Temperature Humidity Point OK

oF oC Percent oF oC

Fresh fruits and

vegetables: — Continued

Peas:

(green, in pods) . . 32 0.0 95 - 98 30.9 –0.6 Yes

 . . . . . . . . . . . . . . . . . (pods)

 . . . . . . . . . . . . . . . . . 29.9 –1.2

 . . . . . . . . . . . . . . . . . (shelled)

Peppers (sweet) . . . . 45 - 55 7.2 - 12.8 90 - 95 30.7 –0.7 No

Pineapples:

Mature-green . . . . 50 - 55 10.0 - 13.0 85 - 90 30.0 –1.1 No 

Ripe Fruit . . . . . . . . . 45 7.2 85 - 90 30.0 –1.1 No

Plums and Fresh

Prunes . . . . . . . . . . 32 0.0 90 - 95 30.5 –0.8 No

Potatoes:

Early crop for

table . . . . . . . . . . 50 - 60 10.0 - 15.6 90 30.9 –0.6 No

Early crop for

chipping . . . . . . . 65 - 70 18.3 - 21.1 90 30.9 –0.6 No

Late crop for

table . . . . . . . . . . 40 - 50 4.4 - 10.0 90 30.9 –0.6 No

Late crop for

chipping . . . . . . . 50 - 60 10.0 - 15.6 90 30.9 –0.6 No

Radishes . . . . . . . . . . 32 0.0 95 - 100 30.7 –0.7 Yes

Raspberries . . . . . . . 32 0.0 90 - 95 30.0 –1.1 No

 . . . . . . . . . . . . . . . . . (black)

 . . . . . . . . . . . . . . . . . 30.9 –0.6

 . . . . . . . . . . . . . . . . . (red)

Rhubarb . . . . . . . . . . 32 0.0 95 - 100 30.3 –0.9 No

Romaine . . . . . . . . . . 32 0.0 95 31.7 –0.2 Yes

Salad mixes . . . . . . . 33 0.6 90 - 95 (varies) No

Spinach . . . . . . . . . . 32 0.0 95 - 100 31.5 –0.3 Yes

Squash and

Pumpkins:

Winter . . . . . . . . 50 - 55 10.0 - 12.8 50 - 70 30.5 –0.8 No

Summer . . . . . . . 41 - 50 5.0 - 10.0 95 31.1 –0.5 No

Strawberries . . . . . . . 32 0.0 90 - 95 30.6 –0.8 No

Sweet potatoes . . . . . 55 - 60 12.8 - 15.6 85 - 90 29.7 –1.3 No

Tangerines . . . . . . . . 40 4.4 90 - 95 30.1 –1.1 No
86

Table III-1.—Recommended Protective Services for Perishable Foods During

Transit — Continued

Top-ice

Recommended Desired Highest and/or1

Transit Relative Freezing Package-ice

Product Temperature Humidity Point OK

oF oC Percent oF oC

Fresh fruits and

vegetables: — Continued

Tomatoes:

Mature-green . . . . 55 - 70 12.8 - 21.1 90 - 95 31.0 –0.6 No

Pink . . . . . . . . . . . . 46 - 50 7.2 - 10.0 90 - 95 31.1 –0.5 No

Watermelons . . . . . . 50 - 60 10.0 - 15.6 90 31.3 –0.4 No

Canned Foods4 . . . . — — — — — —

Dairy Products:

Butter:

Fresh . . . . . . . . . 39 3.9 75 - 85 No

Frozen . . . . . . . . –10 –23.3 No

Margarine . . . . . . . 35 1.7 60 - 70 No

Milk (whole) . . . . . 32 - 34 0.0 - 1.1 ———— 31.0 –0.6 No 

Cheese5 . . . . . . . . . 34 - 40 1.0 - 4.0 65 - 70 No

Ice Cream . . . . . . . –20 - –15 –29 - –26 ———— 21.0 –6.0 No

Fresh and Cured Meat and 

Seafood6 . . . . . . . . — — — — — —

Frozen Foods7 . . . . . — — — — — —

Poultry and Eggs:

Fresh . . . . . . . . . . . 26 - 34 -3.0 - 1.1 90 - 95 27.0 –2.8 Yes

Hard, chilled . . . . . 0 - 26 –18 - –3 90 - 95 27.0 –2.8 No

Eggs . . . . . . . . . . . 40 - 45 4.4 - 7.2 80 - 85 28.0 –2.2 No

1 Make sure products are packed in moisture resistant containers before applying top- or package-ice.

2 Florida and Texas oranges shipped from cold storage or those that will be in transit for more than 5 days should be 

held at 32–34oF (0.0o to 1.1oC). Arizona and California oranges should be shipped at 38o to 48oF. 3 Early Bartlett pears that are ripened in transit should be shipped at 55–60oF. 4 See text page 57 and table 4.

5 See text page 60 and table 5.

6 See text page 62 and table 6.

7 All frozen foods should be shipped at 0oF (–18oC) or below.
Selected Bibliography

American Society of Heating, Refrigerating, and Air-Conditioning Engineers, ASHRAE

Handbook—Refrigeration Systems and Applications, Atlanta, GA, various editions.

Ashby, et al., User’s Guide to the RTF Truck Trailer Classification, Transportation Tips No.

8, AMS-TMD, U.S. Department of Agriculture, Washington, DC, March 1989.

Frozen Food Roundtable, Frozen Food Handling and Merchandising—A Code of Recommended Practices, Washington, DC, 1992.

Hardenburg, R.E., et al. The Commercial Storage of Fruits, Vegetables, and Florist and

Nursery Stocks, Agricultural Handbook No. 66, ARS, U.S. Department of Agriculture,

Washington, DC, 1986.

Kasmire, R.F. and R. Tom Hinsch, Maintaining Optimum Transit Temperatures in Refrigerated Truck Shipments, University of California Perishables Handling Supplement No. 2,

University of California, Davis, CA 95616, and ARS, U.S. Department of Agriculture, Fresno, CA, April 1987.

Lipton, W.J. and John M. Harvey, Compatibility of Fruits and Vegetables During Transport

in Mixed Loads, MRR-1070, ARS, U.S. Department of Agriculture, Washington DC, May

1977.

McGregor, Brian M., Tropical Products Transport Handbook, Agricultural Handbook No.

668, U.S. Department of Agriculture, Washington, DC, 1987.

Nicholas, C.J., Export Handbook for U.S. Agriculture Products, Agricultural Handbook No.

593, U.S. Department of Agriculture, Washington, DC, March 1985.

The Packer, Produce Availability & Merchandising Guide, Vance Publishing Corp., Overland Park, KS, 1993.

The Refrigeration Research Foundation, Commodity Storage Manual,

International Association of Refrigerated Warehouses, Bethesda, MD.

Transfresh, Fresh Produce Mixer & Loading Guide, Transfresh Corp., Salinas, CA, 1988.
Contact the Refrigerated Transportation Library, Department of Pomology, Wickson Hall,

University of California, Davis, CA 95616, for a catalog of videos, slide sets, and printed

material that may be either purchased or obtained free. The items in the catalog are of interest to those involved in the transportation of perishable foods. It comprises the library of the

Refrigerated Transportation Foundation and other resources available from the University of

California, Davis, Cooperative Extension and the U.S. Department of Agriculture.

Preferred Citation

Ashby, B. Hunt. Protecting Perishable Foods During Transport by Truck. 

U.S. Department of Agriculture, Agricultural Marketing Service, September 1995, 

reprinted July 2006. Web. <http://dx.doi.org/10.9752/TS024.07-2006> 

Other Resources