United States

Department

of

Agriculture

Agricultural

Marketing

Service

Fruit and

Vegetable

Division

Processed

Products 

Branch

Grading Manual for

Tomato Sauce

November 1994
Tomato Sauce

Grading Manual

November 1994

This manual is designed for Processed Products Branch Personnelof 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 specifications

and special procedures.

The citation of any data, criteria, techniques, illustrations, copyrighted material, or pictorial

representationaccredited to private authorship is used with the permissionof the individuals

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.

Following the suggested guidelines inthis manualdoes notexcuse failure to comply with the

Federal Food, Drug, and Cosmetic Act or any other applicable Federal or State laws or

regulations.

ExceptforofficialUSDAinspectionaidsor devices and color guides (or standards) produced

underlicense of theDepartment,the mentionof 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 inquires to:

Chief, Processed Products Branch

Fruit and Vegetable Division, AMS

U.S. Department of Agriculture

P.O. Box 96456, Rm. 0709, South Building

Washington, DC 20090-6456
Tomato Sauce

Grading Manual

November 1994

TOMATO SAUCE GRADING MANUAL

TABLE OF CONTENTS Page No. 

I. DESCRIPTION OF PRODUCT. ........................................ 1

A. Refractive Index Versus Salt-Free Tomato Solids. ................ 1

B. History and Development of the Product. ....................... 1

II. INGREDIENTS. ...................................................... 2

A. Tomato Pulp. ................................................. 2

B. Other Ingredients. ............................................. 2

III. PROCESSOR CONTROL. ............................................ 3

A. Color Control. ................................................. 3

B. Consistency Control. .......................................... 3

C. Flavor Control. ................................................ 3

IV. GRADING THE PRODUCT. ........................................... 4

A. Equipment Needed. ........................................... 4

B. Suggested Order of Grading. ................................... 4

V. EXAMINATION FOR FILTH AND EXTRANEOUS MATTER. .............. 11

VI. CERTIFICATION. .................................................... 12

SCORING TOMATO SAUCE COLOR OBJECTIVELY .......................... 13
Tomato Sauce

Grading Manual

November 1994

1

I. DESCRIPTION OF PRODUCT.

While there are many condiment sauces which contain tomato pulp as one ingredient, the

tomato sauce standards cover only those sauces that are composed primarily of spiced

concentrated tomato pulp which have a refractive index of 1.3455 or more.

Tomato sauce is a concentrated tomato product thathas a refractive index value of not less

than 1.3455.

A. Refractive Index Versus Salt-Free Tomato Solids.

Because of the practicalimpossibilityofdetermining the percentageof salt-free

tomato solids in a product which may contain added salt, sugar, vinegar, and

other vegetable flavoring ingredients, the concentration requirement of the

product is given in terms of the refractive index of the filtrate. The refractive

index while easily and accurately measured, however, is not accurately

convertible to total solids, specific gravity, salt-free tomato solids or sucrose in

a product of this type. It is believed, however, that if the refractive indexfalls at

1.3455 or above and the color, flavor, and consistency of the sauce falls in the

Grade A or Grade B range, there will be no question about proper

concentration of the tomato ingredient.

B. History and Development of the Product.

Tomato sauce was probably developed by the first packers as a by-product of

canned tomatoes; that is, a product to utilize surplus pulp made from tomato

peelings and trimmings. Today in many plants it is still a by-product line--a

place for the excess pulp from canning or, more importantly, a product to utilize

residual tomato material after the first and often better flavored pulp has been

extracted for use as tomato juice. At other plants the production of tomato

sauce is a "main line" operation and the tomato ingredient consists principally

of whole, pulped tomatoes. A more recent trend is the increased use tomato

concentrates in the manufacture of tomato sauce.

Sauces made from residual material are often highly spiced and may contain

Cayenne pepper. Such sauces are often called "hot sauce" by the

manufacturers. In the United States grade standards, no distinction is made

between sauces on the basis of the source of the tomato ingredient or the

spices used. In fact it is not always possible to be certain of the source.

Consistencymaybe better in product made from residualmaterialforthe same

percent soluble solids.
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2

In recent years, tomato sauce has been used quite extensively in cooking

wherever tomato paste or tomato puree is used, or, as a condiment. It has, to

a large extent, replaced retail size cans of tomato puree on many grocery

shelves. The added spices are a convenience which appeals to home cooks.

II. INGREDIENTS.

The ingredients used in tomato sauce maybe similar to those used in tomato catsup or may

vary considerably. Company formulas can vary, depending on ethnic and consumer

preferences. Sugar is usually added only in very small amounts, if at all, in tomato sauce while

in tomato catsup approximately 50 percent of the total solids is due to added sugar. The

tomato ingredient may be previously manufactured tomato paste or puree if such ingredient

is declared on the label.

A. Tomato Pulp.

Tomato pulp supplies most of the important characteristics of the product. In

order to obtain the desired consistency at the refractive index specified for

tomato sauce, the tomato pulp from which the sauce is prepared, must be of

high consistency. The pulp must have been produced in a manner so that its

consistency is relatively high at refractive indexes as low as 1.3455.

Among practices which tend to increase the consistency of tomato pulp are:

1. Hot break process to preserve the action of pectic substance;

2. Recooked peelings, seed and other residue from juice 

extraction;

3. Extracted high-fiber pulp from tomato juice for canning;

4. Hard-meated tomatoes, particularly pear-shaped varieties; and

5. Milled pulp (stacked fiber).

B. Other Ingredients.

There are no standardized formulasbetweenmanufacturers with respect to the

amounts of sugar or vinegar or of the amount, type, or quality of the spices,

onion, garlic, or other flavoring ingredients. Any vegetable flavoring such as

peppers, onion, or garlic is usually added in finely ground form prior to

concentrating the pulp. Just before finishing, the other spices in the form of

spice oils or extracts, sugar, and salt are added. The product is usually slightly

salted.

The processor usuallydeterminesthe finishing pointbyusing the refractometer.
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Grading Manual

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3

III. PROCESSOR CONTROL.

Prior to the manufacture of the product, certain specifications of quality will have been

establishedcovering suchfactorsas color,consistency, absence ofdefects,flavor,acidityand

refractive index. Formulas will have been devised and methods of processing developed to

meetthe requirements. Quality control consists of making such adjustments as are necessary

to meet the specifications. Samples are examined during and after the process in order to

determine what adjustments are to be made.

A. Color Control.

Color of the pulp and also ofthe product is evaluated based on comparing the

product color with the spinning discs as prescribed inthe United States grade

standards, color plates, colorimeter readings,and standardreferencesamples

of product. Failure of the product to meet the color requirement may

necessitate anadjustment in the packing practice, suchas, more pulp or better

pulp in the product, or a change in the manufacture of the product, depending

on the cause of the loss of color.

B. Consistency Control.

The amount of pulp needed to produce the desired consistency depends to a

large extent on the quality of the pulp with respect to the size and character of

the insoluble material, the amount and effectiveness of the pectins and gums

present. To maintain good quality control of tomato sauce the quality of the pulp

should be as uniform as possible. Consistencyis adjusted during processing

by measuring certain characteristics ofthe hot sauce or of the cooled product

and making adjustments by increasing ordecreasing the concentrationto meet

the desired quality.

C. Flavor Control.

Flavor control is usually accomplished by tasting samples and comparing them

with standard reference samples, making adjustments to the formula, as

necessary.
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Grading Manual

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4

IV. GRADING THE PRODUCT.

A. Equipment Needed.

1. Scale and pan.

2. Vacuum gauge.

3. Headspace gauge.

4. Large flat white trays and 12"x18" (outside dimension) shallow white

trays .

5. Graph paper.

6. Equipment for determining tomato products color.

7. Refractometer.

8. Bostwick consistometer.

9. White plastic sheet and clear plexiglass sheet, 18"x18"x3/16".

10. Mold counting equipment.

11. Equipment for making filth determination.

12. Inspection instructions for tomato products, grades, and definitions.

13. Score sheets and other inspection forms.

14. U.S. Standard No. 12 sieve screen (optional)

B. Suggested Order of Grading.

1. Afterthe nonqualityfactors (codes, netweights, vacuum, etc.)have been

recorded, evaluate and grade the sample units on a container-bycontainer basis.

The consistency of tomato sauce is partly due to the pectin in the

product. If the jell is broken by hard stirring and beating, the consistency

will change. Refractometer readings, however, may not be accurate if

taken only from the most liquid portion at the top of the container. For

these reasons the sample unit should be prepared by stirring gently,

just enough to fold in excessive liquid portions, before taking the

refractometer reading.

Solids content in tomato sauce is expressed in terms of the refractive

index (Methods of Analyses for Tomato Products, Solids Content

Determinations).

2. Stir each container gently, determine and record the refractive index.

This maybe read from a direct smear or if there is difficultyin obtaining

a clear line, it may be necessary to take the reading on the filtrate.
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5

3. Refer to the color score guide found under the section for color of the

U.S. grade standards for tomato sauce to evaluate color. Accuracy

depends onapproved lighting,reliable equipment,and good technique.

If using USDA-approved colorimeters to determine tomato sauce color,

refer to the APPENDIX in this manual. Otherwise:

Determine the color score using the Macbeth-Munsell Disks

Colorimeter--Type 1.

Grade A Color (Good color). Record a score of 21 to 25 points if the

color of the tomato sauce is as red or more red than the prescribed

combinations of the spinning Munsell disks described in the U.S.grade

standards.

Grade B Color (Reasonably good color). Record a score of 17 to

20 points if the tomato saucemeetsorexceeds the requirements for

U.S.Grade B Colorin the U.S.grade standards but fails to meet the

requirements for good color.

Substandard Color. Any color that is less red than Grade B or not

typical of tomato sauce would receive a score of 16 points or less.

4. Determine the consistency by using the Bostwick Consistometer or

other equipment which gives equivalent results. Refer to "Methods of

Analyses for Tomato Products, Determination of Consistency."

Consistency is determined from the product as it comes from the

container. It may be mixed by stirring gently, taking care to minimize

incorporating airinto the product. The consistometer must be clean and

dry for each determination.

Place on a steady support and level by means of the leveling screws.

Mix sample by gently stirring and pour immediately into reservoir

chamber of the consistometer. The temperature of the product in the

consistometer should be as close as practicable to 20 degrees Celsius

(68° F). Slightly overfill the reservoir, avoiding incorporation of air

bubbles. Pass a straight-edge across the filled chamber to remove

excess product, starting at the gate and working toward the back of the

reservoir. Release the gate using gradual pressure on the release lever.

Hold the instrument steady as the gate is released. Note the time

interval, and, after 30 seconds, measure the maximum distance of

product flow. Read flow distance to the nearest 0.1 cm.
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Recordthe Bostwickconsistometerreading incentimetersonthe score

sheet.

Place a tablespoon of tomato sauce on a flat dry tray or on a flat

transparent plastic plate located over a sheetof graphpaper (1/16 inch

graduations) and determine the amount of"weeping" after two minutes.

This test for serum separationis a supplement to the testforconsistency

to help determine ascorepoint value. Record the amount of separation

on the scoresheet. If there is very little separation of free liquid at the

end of two minutes, the score maybe in the Grade A range with respect

to free liquid. A narrow ring of free liquid averaging 5 mm (3/16 inch)

around the mass is allowed in U.S. Grade A. A ring of free liquid

averaging 10 mm (3/8 in) is permitted in U.S. Grade B.

Use the score point guide in this sectionfor consistencyand assignthe

score for consistency and separation of free liquid. When several

characteristics of a factor of quality must be considered you are

expected to exercise sound judgment in weighing the effect of such

characteristics in assigning score points. The following table is

provided as a guide for scoring consistency. Note that a consistometer

reading of less than 3 cm is considered "excessively stiff."

SCORE POINT GUIDE -- CONSISTENCY

Points Consistometer Readings (cm) Free Liquid (inch)

U.S. Grade A

25

24

23

22

4.0 - 7.0

7.1 - 9.0

9.1 - 11.0

11.1 - 12.0

Not More than 5 mm

(3/16 in)

1/16

2/16

3/16

U.S. Grade B

21

20

19

18

3.8 - 3.9 or 12.1 - 13.0

3.6 - 3.7 or 13.1 - 13.7

3.4 - 3.5 or 13.8 - 14.4

3.0 - 3.3 or 14.5 - 15.0

Not more than 10 mm

(3/8 in)

4/16

5/16

6/16

Substandard More than 15.0 less than 3.0 More than 3/8 inch

Record the score points for consistency on the score sheet.

5. Determine the score points for defects.

The scoring of defects is based on the degree of freedom from such

defects as dark brown or black specks, whole seeds, peel, core

material, other similar material that affect the overall appearance of the

product. Next, take a 100 gram sub-sample, with an adjusted Tomato

Soluble Solids (TSS) of 8.0 to 9.0, and spread it over a smooth white
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7

surface of at least 968 square centimeters (150 sq in). One way to

accomplish this is with the use of a 12"x18" shallow white tray:

Transfer 100 grams of tomato sauce, prepared as indicated above,

into the shallow tray. Tap the edges of the trayto distribute the product

evenly at least 968 square centimeters (150 sq in) towards the edges

of the tray.

Another more efficient method is to use a:

White plastic sheet, 18"x18"x3/16"; and

Clear plexiglass sheet, 18"x18"x3/16"

Transfer 100 grams of tomato sauce,prepared as indicated above,to

the center of the white sheet ofplastic. Then place the clear plexiglass

sheet over the white plastic sheet and press gently. This will force the

sauce out towards the edges. Once you have spread the sauce an

average diameter of 14 to 15 inches, leaving the clear plexiglass sheet

in place, you will be able to count the dark brown and black specks,

whole seeds, peel, and core material, using Table I in the U.S. grade

standards for tomato sauce. Other methods maybe used to spread the

sauce as long as the 100 grams of sauce are spread overat least a 150

square inch area.

Next, examine the entire contents of the container for whole seeds.

Count the number of whole seeds in the sample unit.
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Checking for whole seeds may be done when:

a. The presence of seeds maybe indicated from a routine (100 g)

check for other defects; or

b. There is a history of finding whole seeds.

Checking for whole seeds may be accomplished by:

a. Examining the entirecontentsof the container bypouring smaller

subsamplesofthe product onto a trayand spreading the material

thin enough to detect any seeds that may be present; or

b. Washing the entire contents of the container through a U.S.

Standard No. 12 screen (if available) and count the seeds

remaining on the screen. 

6. Record the score points for defects on the score sheet using the

following table which corresponds with the criteria for Defects in Table

I of the U.S. grade standards:

DEFECTS

COLOR, TYPE, OR SIZE

CLASSIFICATION

Minor Major Severe

Dark brown or black specks:

 Larger than 1.0 mm (1/32 inch), up to and including 

 3.2 mm (1/8 inch)

X

 Larger than 3.2 mm (1/8 inch), up to and including 

 6.5 mm (1/4 inch)

X

 Larger than 6.5 mm (1/4 inch) X

Pieces of peel exceeding 5 mm (3/16 inch) X
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The following is a guide in regulating score points with relation to the number and type of

defects found.

Severe Major Minor/Total Score Points Grade

0 0 0 - 3 25

A

0 0 4 - 6 24

0 0 7 - 9 23

0 0 10 - 12 22

0 0 13 - 15 21

0 1 16 - 22 20

0 -- 23 - 29 19 B

0 2 30 - 36 18

The most severe defect(s) limits the score. Examples: 

1 major and 10 minor = 20 points

2 major and 12 minor = 18 points

Rejection numbers for various defect classifications:

Grade

Defect Classification

Severe Major Minor/Total Seeds

A

AC RE AC RE AC RE Not more than 1 seed/100 oz

N/A 0 1 15 16

B 0 1 2 3 36 37 Not more than 5 seeds/100 oz

Remember to use the above chart as a guide. In the U.S. grade standards, any combination

of defects present that does not materially affect the appearance or eating quality is Grade

A. Any defects present that materially affect but does not seriously affect the appearance or

eating quality is U.S. Grade B.
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7. Determine the score points for flavor and odor. Tomato sauce is a

formulated product and the flavor can be adjusted considerably by the

use of different spices, amounts of sugar and acid, as well as by

differing amounts of tomato pulp or different qualities of tomato pulp.

Flavor is an important characteristic of tomato sauce and every effort

should be made to accurately evaluate this factor to minimize personal

preferences. The following may be helpful:

Tomato sauce that has a good bright color and a strong, pleasing odor

will usually have a good, acceptable flavor. Therefore, in line with the

wording of the standards if the tomato sauce has a flavor that indicates

thatgood quality ingredients were used insuitable proportions and that

the process was proper, a score of 21 to 25 points may be given. The

proportions of the various ingredients must be considered because

these strongly affect the acceptability of the flavor; thatis, if the sauce is

extremely acidic or very bland or too sweet, it probably would not be

GradeA. No salt, excessive salt, or an excess of any condiment (except

Cayenne pepper in a product declared to be a hot sauce) would lower

the score. Lack of a clean, distinct tomato flavor or bitterness due to

crushed seeds would tend to also lower the score.

Good flavor and odor mean a distinct tomato flavor and odor. Such

flavor and odor is free from scorching or any other objectionable flavor

and odor.

Reasonably good flavor and odor mean a flavor and odor in which

there maybe slight tracesofundesirable flavor,suchas scorched,bitter,

or astringent flavor, but is free from objectionable off-flavors and odors.

Substandard flavor and odor mean the flavor and odor are off-flavor

and do not meet the requirements for reasonably good flavor.

The flavor of tomato sauce and hot sauce must be evaluated quickly.

The first impressionis the best impression. Taste a small portionof the

product and assign the score points for flavor and odor.
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8. Determine the finish of the tomato sauce.

Good finish means the product is evenly comminuted, has uniform,

smooth texture, and is free from noticeable lumps.

Poor finish means the product fails to meet the definition of "good

finish".

Indicate the quality of the finish as either "good" or "poor".

9. Totalthe scorepointsfor defects, consistency, color, and flavorfor each

sample unit. If any whole seeds were found, before assigning the "lot as

a whole U.S. grade," remember to go back and compare the total

number of whole seeds found with the total amount of product in all the

sample units. Whole seeds allowances are based on each 100 ounces

of product. To determine the number of whole seeds per 100 ounces,

dividethe number of seeds found into totalnetweight of all sample units.

Example: 2 whole seeds are found in 620 oz of product.

 620/2 = 1 seed per 310 oz.

One whole seed per 100 oz is allowed in Grade A, so 1 seed per 310

oz is allowed in Grade A.

V. EXAMINATION FOR FILTH AND EXTRANEOUS MATTER.

Before assigning the "lotas a whole U.S.grade" to any processed food product, the following

analyses are to be made:

Mold counts. Refer to "Methods of Analyses for Tomato Products Mold Count"

Fly egg and maggot determination.

Insect fragment and other light filth analyses.

(These to be made only if specifically directed or requested or if there is any question about

sanitary manufacture or suitable raw materials.)
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VI. CERTIFICATION.

In addition to applying File Code 165-A-1, Certification, the following information is also

applicable to the certification of tomato sauce. The following procedure may be used for

certification of the refractive index values.

Any individual sample unit may be as low as 1.3447 (corrected to 20.0 degrees Celsius)

provided that the average of all sample units in the lot is equal to or greater than 1.3455.

If a product offered for inspection as tomato sauce does not meet this tolerance, the grade

statement should be similar to:

"NO APPLICABLE STANDARDS FOR GRADES OF THIS PRODUCT -- refractive index

less than requirement for tomato sauce."

If the tomato sauce contains an excess amount of Cayenne pepper, certify the grade but

indicate in the body of the certificate:

Flavor -- highly spiced.
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Appendix

November 1994

13

SCORING TOMATO SAUCE COLOR OBJECTIVELY

In addition to the use of the Macbeth-Munsell colorimeter other selective electronic color

meters may be used as an alternate means of determining color in tomato sauce. Such

meters shall be calibrated to indicate that the color of the product is as red or more red than

that produced by spinning the Munsell color disks in the combinationas described in the U.S.

grade standards.

Methods

Tomato Sauce. Color of tomato sauce is measured as the product comes from the

container. No dilution is necessary. The sample should be stirred prior to measurement.

During stirring, care should be taken to avoid incorporation of air bubbles into the product.

Transfer the sample to the appropriate colorimeter sample cup for measurement.

Colorimeters - Operation, Standardization and Color Score Calculation

Hunter Colorimeters:

Instrument. Use Hunterlab D25-D2 series with type A optical head.

Selection and UseofSample Cups. On request, U. C. Davis will supply several sixounce cans of the calibration standard (see page 12 for address). 

Color Score Point Conversions - Hunter Colorimeter

The following equation is used for calculation of tomato sauce color score:

Score = -154.39 + 1.1142(aL) + 22.596(bL) - 0.86736(bL)

2

Agtron Colorimeters:

Agtron M400 and M500. Use black and red discs to set zero on scale.

Selection and Use of Sample Cups. (Agtron M400 and M500 Models). Use only

pre-selected cups. On request, U. C. Davis will supply several six-ounce cans of the

standard (see page 12 for address).
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Appendix

November 1994

14

Color Score Point Conversions - Agtron Colorimeters

The following equation is used for calculation of tomato sauce color score:

Agtron M400 and M500 Colorimeters

Score = -25.002 + 1.5234(R) - 0.0092174(R2) - 0.25817(G)

Gardner Colorimeters:

Instrument. Use Gardner models XL20 or XL23 series, XL-805 or Colorgard

2000/05 models.

Selection and Use of Sample Cups. Use only pre-selected cups. On request, U.

C. Davis will supply several six-ounce cans of the calibration standard (see below for

address).

Color Score Point Conversions - Gardner Colorimeters

The following equation is used for calculation of tomato sauce color score:

Score = -193.20 + 1.0211(aL) + 27.649 (bL) - 1.0175(bL)

2

Information and Assistance

Assistance in colorimeter standardization and operation may be obtained by

contacting your supervisor at the local area field office.

For further information about obtaining cans of tomato color calibration standards to

use to calibrate these colorimeters, please contact:

Teri Wolcott

Department of Food Science and Technology

Cruess Hall

University of California

Davis, California 95616

(916) 752-8079