Grading Manual 

for 

Pineapple Juice

February 2011

United States

Department of

Agriculture

Marketing and

Regulatory

Programs

Agricultural

Marketing 

Service

Fruit and 

Vegetable

Programs

Processed 

Products 

Branch
PREFACE

This manual is designed for Processed Products Branch personnel of the U.S. 

Department of Agriculture. Its purpose is to give background information and 

guidelines to assist in the uniform application and interpretation of U.S. grade 

standards, other similar specification and special procedures. 

The citation of any data, technique illustrations, copyrighted material or pictorial 

representation accredited to private authorship is used with permission of the 

individual or sources cited. Unless a specific reference is cited, the information in 

this manual has been compiled or developed from sources available to the public 

as well as from technical knowledge of personnel in the Department. 

Compliance with the suggested guidelines in this manual does not excuse failure 

to comply with Federal Food, Drug, and cosmetic Act or any other applicable 

Federal or State laws or regulations.

Except for official USDA inspection aids or devices and color guides (or

standards) produced under license of the Department, the mention of any 

supplier, patented device, product, brand name or equipment does not imply 

endorsement by the Department over any other similar, or equally effective 

material.

Address inquiries to:

Chief, Processed Products Branch

Fruit and Vegetable Programs, AMS

U.S. Department of Agriculture

STOP 0247

1400 Independence Ave., SW

Washington, D.C. 20250
Pineapple Juice

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2

GRADING MANUAL

for

PINEAPPLE JUICE

TABLE OF CONTENTS

Page

I. SAMPLING PROCEDURES ......................................................................... 4

II. NONQUALITY PROCEDURES ................................................................... 4

III. HEADSPACE AND FILL OF CONTAINER ................................................. 4

IV. VOLUME MEASUREMENT ........................................................................ 5

A. Measuring Flask Method ................................................................... 5

B. Net Weight to Fluid Ounces Conversion Method .............................. 5

V. STYLES ....................................................................................................... 6

A. Unsweetened .................................................................................... 6

B. Sweetened ....................................................................................... 6

VI. PASTEURIZATION .................................................................................... 6

VII. MIXED LOT OF UNSWEETENED AND SWEETENED JUICE ................. 6

VIII. METHODS OF ANALYSES ...................................................................... 6

A. Brix Measurement ............................................................................ 6

B. Acid Determination ............................................................................ 6

IX. SUGGESTED ORDER OF GRADING A SAMPLE UNIT ............................ 7
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GRADING MANUAL

FOR

PINEAPPLE JUICE

I. SAMPLING PROCEDURES 

1. Regulations (109-A-1)

2. Sampling Procedures (120-A-1)

3. Time Sampling (120-A-4)

4. Condition of Container (125-A-1)

5. In-Plant Inspection (160-A-1, 162-A-1)

6. Foreign Material (172-A-1, 172-A-2)

II. NONQUALITY PROCEDURES

1. Time Sampling (120-A-5)

2. Net Contents (128-A-10)

3. Vacuum (128-A-20)

4. Fill of Container (128-A-40), Inspection Procedures (130-A-1) 

5. Brix Measurement (128-A-50, 135-A-3)

6. Mold Count (135-A-8, 135-A-9)

III. HEADSPACE AND FILL OF CONTAINER

Generally, the headspace of containers of pineapple juice need not be 

checked as long as the declared net contents for the particular container 

size is met. The quality control department of some plants may prefer to 

have the headspace recorded for all containers opened for grading. The 

headspace should be recorded for all cans which appear to have lower 

than normal fill before determining net contents. Headspace is generally 

reported in units of 1/32 inch. Headspace measurement is not applicable 

to other container types such as plastic bottles or aseptic brik pack.

The standard of fill of container for pineapple juice, except when the food 

is frozen, is not less than 90 percent of the total capacity of the container, 

as determined by the general method for fill of container prescribed in 21 

CFR 130.12 (b). The net contents may be determined either by direct 

measurement in a volumetric cylinder graduated in fluid ounces or by net 

weight and conversion to fluid ounces. Refer to File Code 130-A-1 for this 

procedure. 

The net contents statement for pineapple juice must be declared in liquid 

measure in the largest whole units (quarts, quarts and pints, or pints, as 

appropriate) with any remainder in terms of fluid ounces or common or 

decimal fractions of the pint or quart.
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III. HEADSPACE AND FILL OF CONTAINER (continuation)

Example:

(1) A declaration of 1 quart liquid measure shall be 

expressed as “Net 32 fl oz (1 qt).”

(2) A declaration of 1-3/4 quart liquid measure shall be 

expressed as, Net contents 56 fluid ounces (1 quart 1-1/2 

pints)” or as “Net 56 fluid oz (1 qt 1 pt 8 oz),” but not in 

terms of quart and ounce such as “Net 56 fluid oz (1 quart 24 

ounces).”

(3) A declaration of 2-1/2 gallons liquid measure shall be 

expressed as “Net contents 2-1/2 gallons,” “Net contents 2.5 

gallons,” or “Net contents 2 gallons 2 quarts” and not as “2 

gallons 4 pints.”

When the contents are less than one pint only the fluid 

ounces must be declared.

IV. VOLUME MEASUREMENT

A. Measuring Flask Method

Glass flasks are available that are accurately calibrated for 

measuring volume of liquids. There are two important things to 

remember when using this method. The flask is calibrated for 

volume of a liquid at a standard temperature, usually 20 degrees C. 

The legend is etched on each flask. The juice must be at this 

temperature for accuracy. Also, it is important not to incorporate air 

into the liquid when filling the flask to permit any occluded air to 

escape.

B. Net Weight to Fluid Ounces Conversion Method

Take the net weight of the juice. Convert this weight to volume 

measurement by the following formula:

Net contents = Net weight (avoir. oz.) x 0.9614

 Specific gravity at 20 degrees C
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Example:

Pineapple juice No. 3 cylinder

Net weight – 49.2 ounces

Refractive Index (20 degrees C) – 1.3414 

(See File Code 135-A-50 for Specific Gravity.)

Specific gravity – 1.02289

Net contents = (49.2) (0,9614) = 47.3 = 46.2 fl oz. 

 1.02289 1.02289

V. STYLES

1. Unsweetened - no sweetener added.

2. Sweetened - any safe and suitable dry nutritive carbohydrate 

sweetener approved by FDA may be added.

VI. PASTEURIZATION

The juice is pumped to a heat exchanger or pasteurizer where it is brought 

up to a temperature of 190 degrees F just prior to filling.

VII. MIXED LOT OF UNSWEETENED AND SWEETENED JUICE

Under normal packing practice unsweetened style juice would not be 

mixed with sweetened style. However, if a lot is inadvertently mixed style, 

the packer may wish to segregate the lot before offering for grading. In the 

event the packer declines the segregation, grade the lot according to the 

style that it is offered for, either unsweetened style or sweetened style.

VIII. METHODS OF ANALYSES

A. Brix Measurement

Procedures for taking Brix measurements are outlined in 

File Code 135-A-3 (Technical Inspection Procedures - Brix 

Measurement).

B. Acid Determination

Transfer 10 mL of well-mixed juice to 250 mL Erlenmeyer flask. 

Rinse inside of flask down with approximately 25 mL distilled water. 

Add 3 or 4 drops of phenolphthalein indicator or other suitable 

indicator. Titrate this solution with approximately 0.1N sodium 

hydroxide (NaOH) to the first signs of a permanent end point 
Pineapple Juice

 February 2011 

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(Acid Determination Continued)

according to the indicator used (pink in the case of phenolphthalein.

The acid content is expressed in grams anhydrous citric acid per 

100 mL of juice according to the following formula:

mL NaOH x N of NaOH x 0.64 = gm anhydrous citric acid/100 mL 

of juice.

IX. SUGGESTED ORDER OF GRADING A SAMPLE UNIT

1. Draw 500 mL (250 mL for containers 12 fl. oz. or less) of well-mixed 

pineapple juice. This could be a portion of the contents of a 

container, the entire contents of a container, or a composite of 

more than 1 container from a particular code.

2. Evaluate the color by pouring the suggested amount (250 mL or 

500 mL) into a clean glass cylinder approximately two inches in 

diameter and twelve inches tall and viewing the juice through the 

cylinder under good lighting conditions.

Grade A – the color should be very good, bright and typical as 

described in the standards. Pineapple juice that falls into this 

classification may be assigned a score of 17 to 20 points.

Grade B – the color should be good and may be slightly dull but not 

off-color. Pineapple juice that falls into this classification may be 

assigned a score of 14 to 16 points and should not be graded 

above U.S. Grade B regardless of the total score for the product.

The more prevalent color of pineapple juice in the marketplace is 

light yellowish beige. Another variety from the Caribbean (Puerto 

Rico) yields a golden amber or golden pinkish cast. This range in 

color is normal as long as it is typical of the variety. However, 

watch for “abused” juice such as: oxidized, caramelized, scorched, 

stack burn, etc.

Reasonable allowance should be made for pineapple juice made 

from concentrate, as long as it is typical of the color of the 

processed product. Any juice, which has been improperly prepared 

or processed, is subject to impaired color - - generally because of 

excessive or prolonged heating.
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3. Evaluate the juice for absence of defects. In addition to the 

subjective evaluation for dark specks and seed or shell particles, 

the juice should be evaluated for the amount of “finely divided 

insoluble solids.” The quantity of “finely divided insoluble solids” as 

described in the standards is determined as follows:

Measure 50 mL of thoroughly stirred pineapple juice into a coneshaped graduated tube of the long-cone type, measuring 

approximately 4-3/16 inches from tip to top calibration and having a 

capacity of 50 mL.

Place the tube in a suitable centrifuge, the approximate speed of 

which is related to diameter of swing in accordance with the table 

below. The word “diameter” means the overall distance between 

the tips of opposing centrifuge tubes in operating position.

The milliliter reading at the top of the layer of “insoluble solids,” 

after centrifuging 3 minutes, is multiplied by two to obtain the 

percentage of “insoluble solids.” 

Approximate revolutions

Diameter per minute 

10 inches ........................................................................... 1,609

10-1/2 inches ..................................................................... 1,570

11 inches ........................................................................... 1,534

11-1/2 inches ..................................................................... 1,500

12 inches ........................................................................... 1,468

12-1/2 inches ..................................................................... 1,438

13 inches ........................................................................... 1,410

13-1/2 inches ..................................................................... 1,384

14 inches ........................................................................... 1,359

14-1/2 inches ..................................................................... 1,336

15 inches ........................................................................... 1,313

15-1/2 inches ..................................................................... 1,292

16 inches ........................................................................... 1,271

16-1/2 inches ..................................................................... 1,252

17 inches .......................................................................... 1,234

17-1/2 inches ..................................................................... 1,216

18 inches ........................................................................... 1,199

18-1/2 inches ..................................................................... 1,182

19 inches ........................................................................... 1,167

19-1/2 inches ..................................................................... 1,152

20 inches ........................................................................... 1,137
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Compare the results obtained against the allowances in the 

standards.

Grade A – may contain slight amounts of defects (specks, pieces of 

shell, seeds) that do not more than slightly affect the appearance or 

palatability of the juice. Pineapple juice that falls into this 

classification may be assigned a score of 34 to 40 points.

Grade B – may contain moderate amounts of defects (specks, 

pieces of shell, seeds) that do not more than materially affect the 

appearance or palatability of the juice. Pineapple juice that falls 

into this classification may be assigned a score of 28 to 33 points 

and should not be graded above U.S. Grade B regardless of the 

total score for the product.

Dark specks, seed or shell particles, or other defects are evaluated 

by pouring 250 mL portions of the sample onto a flat white grading 

tray (approx. 17” x 12”) and observing the defects present. Also 

evaluate for the allowable amount of “finely divided insoluble solids” 

as previously discussed. Allow 5-26 percent by volume of “finely 

divided insoluble solids” in Grade A and 5-30 percent by volume in 

Grade B. The intent of these tolerances is to allow a little bit more 

pulp in Grade B than in Grade A.

 

4. Evaluate flavor. A proper combination of various pineapple 

characteristics is essential to a high quality pineapple juice flavor. 

Specifically, these are:

(1) A good sugar-acid balance; and 

(2) Pineapple essences which provide the “fruity flavor,” 

bouquet and aroma.

Minimum requirements are provided for sugar, expressed as 

“Degrees Brix,” in grade A and B. Maximum requirements for acid 

are provided in these grades.

Although a sample unit of pineapple juice may meet the 

requirements for a particular grade for both sugar and acid, a 

subjective evaluation must be made with respect to sugar-acid 

balance. For example, if the acidity of the juice approaches the 

maximum for Grade A, the sugar content should be such that the 

juice is not too tart for good flavor balance. On the other hand, if 

the acidity of the juice is quite low, the sugar content should not be 
Pineapple Juice

 February 2011 

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such as to cause the flavor to be too sweet. NOTE: Allow for 

normal sweet taste in the sweetened style.

Pineapple essences must be present to provide a pronounced 

“fruity” flavor characteristic of pineapple juice made from properly 

ripened and properly processed pineapple, in addition to meeting 

sugar and acid requirements in order for the juice to qualify for 

Grade A. If the juice does not have a pronounced pineapple flavor, 

the sample unit must not be classified above Grade B even though 

sugar and acid requirements for Grade A are met.

Also, be alert to scorched and caramelized flavors particularly when 

grading pineapple juice from concentrate. Adverse “de-tinned” can 

flavor should also be watched for.

Grade A (very good flavor) – the juice possesses a distinct varietal 

flavor that is typical of freshly extracted juice (pineapple juice) or 

typical reconstituted juice (pineapple juice from concentrate) that is 

properly processed from mature, well-ripened pineapple. 

Pineapple juice that falls into this classification may be assigned a 

score of 34 to 40 points. 

Grade B (good flavor) – the pineapple juice possesses a normal 

varietal flavor that may be slightly caramelized but is not off-flavor. 

Pineapple juice that falls into this classification may be assigned a 

score of 28 to33 points.

5. Examine for MOLD (and other foreign material) per File Code 

172-A-1.

Prepare the juice for the Howard Mold Counting Procedure as 

follows:

Without incorporating air into the sample unit, thoroughly mix by 

pouring back and forth a minimum of 12 times between two 

containers. After mixing, pour 50 mL of juice into a 50 mL 

graduated conical centrifuge tubes (Corning No. 8300 or 

equivalent). Centrifuge according to the following instructions:

Centrifuge the sample for 10 minutes at a Relative Centrifugal 

Force (RCF) of 1060 g. The reference centrifuge has a radius of 

19.6 cm and attains RCF of 1060 g at a speed of 2200 rpm.
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 February 2011 

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Since many of the centrifuges used in plants and offices differ from 

the AOAC reference, the following equation may be used to calculate 

the speed at which your centrifuge must run to attain RCF = 1060 g.

N1

2

x r1 = N2

2

x r2

Where N1 = 2200 rpm

r1 = 19.6 cm

N2 = speed of centrifuge 

r2 = radius of centrifuge arm

For example, for a centrifuge having a radius of 14.1 cm, determine 

the speed as follows:

N2

2

= N1

2

 r1

 r2 

N2

2

= (2200)2 (19.6)

 (14.1)

N2

2

= (2594)2

N2 = 2594 rpm

Rounding to the nearest 100 rpm, would result in a speed of 2600 

rpm. This is the speed necessary to run the centrifuge to attain the 

proper relative centrifugal force. 

Consult the manufacturer’s instructions for the radius of the 

centrifuge arm. Be certain that the measurement is that taken to 

the bottom of the horizontal centrifuge tube. When setting the 

speed of the centrifuge, it is best to use a tachometer that reads by 

direct contact. Strobe type tachometers are not as accurate. 

Centrifuge must be balanced properly. 

AFTER CENTRIFUGING FOR 10 MINUTES, ALLOW 

CENTRIFUGE TO COME TO A STOP GRADUALLY. DO NOT 

USE CENTRIFUGE BRAKE. DO NOT OPEN CENTRIFUGE 

COVER UNTIL THE CENTRIFUGE HAS COME TO A COMPLETE 

STOP.

After centrifuging, read and record the volume of sediment in the 

tube and decant the supernatant liquid without disturbing the 

sediment. Add 0.5 mL hydrochloric acid to dissolve oxalate 

crystals. Add distilled water to the tube to bring to the 10 mL mark. 

Add 5 mL stabilizing solution.
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 February 2011 

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The stabilizing solution may be any one of the following:

1. 0.5 percent Sodium Carboxymethylcellulose

2. 3 to 5 percent Pectin Solution

3. 1 percent Algin Solution

See file code 135-A-6 for preparation of stabilizing solutions.

Thoroughly mix sediment, water, and stabilizing solution and pour 

into a small beaker. Mix by pouring back and forth a minimum of 6 

times between beaker and centrifuge tube. Stir mixture thoroughly 

in beaker and proceed with mold counting according to instructions 

in File Codes 135-A-8 and 135-A-9. Record results and apply 

acceptance criteria from 172-A-2. Lots failing Howard Mold Count 

cannot be assigned a grade. These lots are Grade Not Certified 

(GNC) and fail the Federal Food, Drug and Cosmetic Act.