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United States Standards

for Grades of Canned 

Mushrooms

Effective May 20, 2019
This issue of the United States Standards for Grades of Canned Mushrooms

(84 FR 16381) supersedes the previous issue which has been in effect since

April 7, 1962.

Voluntary U.S. grade standards are issued under the authority of the Agricultural 

Marketing Act of 1946, which provides for the development of official U.S. grades to 

designate different levels of quality. These grade standards are available for use by 

producers, suppliers, buyers, and consumers. As in the case of other standards for 

grades of fresh and processed fruits, vegetables, and specialty crops these 

standards are designed to facilitate orderly marketing by providing a convenient 

basis for buying and selling, for establishing quality control programs, and for 

determining loan values. 

The U.S. grade standards and inspection instructions for all fresh and processed fruits,

vegetables, and specialty crops are available on the internet and upon request at the 

address below. These documents provide detailed interpretations of the grade standards 

and provide step-by-step procedures for grading the product. 

Grade standards are issued by the U.S. Department of Agriculture (USDA) after careful 

consideration of all data and views submitted during rulemaking. The Department 

welcomes suggestions for improving the standards in future revisions. Comments may be 

submitted to, and copies of standards and inspection instructions obtained from: 

Director, Specialty Crops Inspection Division

Specialty Crops Program, 

USDA, Agricultural Marketing Service

1400 Independence Avenue, SW, STOP 0240 

Washington, D.C. 20250

Authority: 7 U.S.C. 1621-1627. 

Note: Compliance with the provisions of these standards shall not excuse failure to 

comply with the provisions of the Federal Food, Drug, and Cosmetic Act, or 

with applicable State laws and regulations.

Non-Discrimination Policy: In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) civil rights regulations and 

policies, the USDA, its Agencies, offices, and employees, and institutions participating in or administering USDA programs are prohibited from 

discriminating based on race, color, national origin, religion, sex, gender identity (including gender expression), sexual orientation, disability, age, 

marital status, family/parental status, income derived from a public assistance program, political beliefs, or reprisal or retaliation for prior civil 

rights activity, in any program or activity conducted or funded by USDA (not all bases apply to all programs). Remedies and complaint filing 

deadlines vary by program or incident.

Persons with disabilities who require alternative means of communication for program information (e.g., Braille, large print, audiotape, American 

Sign Language, etc.) should contact the responsible Agency or USDA's TARGET Center at (202) 720-2600 (voice and TTY) or contact USDA 

through the Federal Relay Service at (800) 877-8339. Additionally, program information may be made available in languages other than English.

To file a program discrimination complaint, complete the USDA Program Discrimination Complaint Form, AD-3027, found online at How to File a 

Program Discrimination Complaint and at any USDA office or write a letter addressed to USDA and provide in the letter all of the information 

requested in the form. To request a copy of the complaint form, call (866) 632-9992. Submit your completed form or letter to USDA by: (1) mail: 

U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, D.C. 20250-

9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov.

USDA is an equal opportunity provider, employer, and lender.
United States Standards for Grades of Canned Mushrooms (May 20, 2019)

1

United States Standards for Grades of Canned Mushrooms

______________________________________________________________________

Section Page No.

Product Description, Color Types, Styles, and Grades ............................................. 2

§52.1481 Product description...................................................................................... 2

§52.1482 Color types of canned mushrooms. ............................................................. 2

§52.1483 Styles of canned mushrooms. ..................................................................... 2

§52.1484 Grades of canned mushrooms. ................................................................... 3

Sizes, Fill of Container, and Drained Weights ............................................................ 3

§52.1485 Sizes of canned mushrooms in the styles of whole and buttons.................. 3

§52.1486 Fill of container for canned mushrooms....................................................... 4

§52.1487 Minimum drained weights for canned mushrooms. ..................................... 4

Factors of Quality.......................................................................................................... 5

§52.1488 Ascertaining the grade................................................................................. 5

§52.1489 Ascertaining the rating for the factors which are scored. ............................. 5

§52.1490 Color............................................................................................................ 6

§52.1491 Uniformity of size and shape. ...................................................................... 7

§52.1492 Defects. ....................................................................................................... 8

§52.1493 Character................................................................................................... 10

Lot Inspection and Certification................................................................................. 11

§52.1494 Ascertaining the grade of a lot................................................................... 11

Score Sheet ................................................................................................................. 11

§52.1495 Score sheet for canned mushrooms.......................................................... 11
United States Standards for Grades of Canned Mushrooms (May 20, 2019) 

2 

Product Description, Color Types, Styles, and Grades

§52.1481 Product description.

Canned mushrooms, as defined in the definitions and standards of identity for canned 

mushrooms (21 CFR 155.201) issued pursuant to the Federal Food, Drug, and 

Cosmetic Act, means the product prepared from the sound, succulent, fresh mushroom 

by proper trimming, washing, and sorting and is packed with the addition of water in 

hermetically sealed containers and sufficiently processed by heat to assure preservation 

of the product. Salt, or monosodium glutamate, or both may be added in a quantity 

sufficient to season the product. Ascorbic acid (Vitamin C) may be added in a quantity 

not to exceed 37.5 milligrams for each ounce of drained weight of mushrooms.

§52.1482 Color types of canned mushrooms.

(a) White or cream.

(b) Brown.

§52.1483 Styles of canned mushrooms.

(a) Whole is the style of canned mushrooms that consists of the caps with attached 

stems which are more than 1/8 inch in length when measured from the under 

side of the cap to the cut end of the stem.

(b) Buttons is the style of canned mushrooms that consists of the caps with 

attached stems which are cut transversely below the veil so that in 85 percent or 

more, by count, of the units the attached stem when measured from the under 

side of the cap to the cut end of the stem does not exceed 1/8 inch in length; and 

in the remaining units none of the attached stems may be more than 1/4 inch in 

length.

(c) Sliced whole is the style of canned mushrooms that consists of units which have 

been sliced from whole mushrooms so that in 80 percent or more, by weight, of 

all the units the direction of the slice is approximately parallel to the longitudinal 

axis of the stem; and not more than 5 percent, by weight of all the units may be 

detached portions of stems.

(d) Random sliced whole is the style of canned mushrooms that consists of units 

which have been sliced from whole mushrooms in a random manner so that the 

direction of the slice may materially deviate from approximately parallel to the 

longitudinal axis of the stem; and not more than 15 percent, by weight of all the 

units may be detached portions of stem. 

(e) Sliced buttons is the style of canned mushrooms that consists of units which 

have been sliced from button mushrooms so that in 90 percent or more, by 

weight, of all the units the direction of the slice is approximately parallel to the 

longitudinal axis of the stem.
United States Standards for Grades of Canned Mushrooms (May 20, 2019) 

3 

(f) Stems and pieces or pieces and stems (hereinafter referred to as stems and 

pieces) is the style of canned mushrooms that consists of units which do not 

conform to any of the foregoing styles and are predominantly cut or broken

portions of the caps and stems and may contain units of any of the foregoing 

styles. 

§52.1484 Grades of canned mushrooms.

(a) U.S. Grade A is the quality of canned mushrooms that possess similar varietal 

characteristics; that possess a normal flavor and odor; that possess a good color; 

that are practically uniform in size and shape, except for the style of stems and 

pieces; that are practically free from defects; that possess a good character; and 

that for those factors which are scored in accordance with the scoring system 

outlined in this subpart the total score is not less than 90 points: Provided, That 

the canned mushrooms may be fairly uniform in size and shape for the applicable 

styles if the total score is not less than 90 points.

(b) U.S. Grade B is the quality of canned mushrooms that possess similar varietal 

characteristics; that possess a normal flavor and odor; that possess a fairly good 

color; that are fairly uniform in size and shape, except for the style of stems and 

pieces; that are fairly free from defects; that possess a fairly good character; and 

that for those factors which are scored in accordance with the scoring system 

outlined in this subpart the total score is not less than 80 points: Provided, That 

the canned mushrooms may fail to meet the requirements for U.S. Grade B for 

the factor of uniformity of size and shape for the applicable styles if the total 

score is not less than 80 points.

(c) Substandard is the quality of canned mushrooms that fail to meet the 

requirements of U.S. Grade B.

Sizes, Fill of Container, and Drained Weights

§52.1485 Sizes of canned mushrooms in the styles of whole and buttons.

(a) No. 0 (Petite) size mushrooms will pass through a round opening 1/2 inch in 

diameter.

(b) No. 1 (Tiny) size mushrooms will pass through a round opening 5/8 inch in 

diameter but will not pass through a round opening 1/2 inch in diameter. 

(c) No. 2 (Small) size mushrooms will pass through a round opening 7/8 inches in 

diameter but will not pass through a round opening 5/8 inch in diameter.

(d) No. 3 (Medium) size mushrooms will pass through a round opening 1-1/8 inches 

in diameter but will not pass through a round opening 7/8 inch in diameter.

(e) No. 4 (Large) size mushrooms will pass through a round opening 1-5/8 inches in 

diameter but will not pass through a round opening 1-1/8 inches in diameter.
United States Standards for Grades of Canned Mushrooms (May 20, 2019) 

4 

(f) No. 5 (Extra Large) size mushrooms are those too large to pass through a round 

opening 1-5/8 inches in diameter.

§52.1486 Fill of container for canned mushrooms.

The standard for fill of container for canned mushrooms is not incorporated in the 

grades of the finished product, since fill of container, as such, is not a factor of quality 

for the purpose of these grades. The standard of fill of container for canned mushrooms 

is such that the drained weight of mushrooms is not less than 56 percent of the water 

capacity of the container if such capacity is less than 11.0 ounces avoirdupois; not less 

than 59 percent of the water capacity of the container if such capacity is 11.0 ounces or 

more but less than 25 ounces avoirdupois; and not less than 62 percent of the water 

capacity of the container if such capacity is 25 ounces avoirdupois or more. Canned 

mushrooms which do not meet this requirement are Below Standard in Fill. 

§52.1487 Minimum drained weights for canned mushrooms.

(a) General. The total weight of drained mushrooms (drained weight) shall be not 

less than that shown for the respective size of containers in Table I of this 

section. 

(b) Method of ascertaining the drained weight. The total weight of drained 

mushrooms is determined by emptying the contents of the container upon a 

United States Standard No. 8 circular sieve of proper diameter containing 8 

meshes to the inch (0.0937±3 percent, square openings) so as to distribute the 

product evenly, inclining the sieve slightly to facilitate drainage, and allowing to 

drain for two minutes. The drained weight is the weight of the sieve and 

mushrooms less the weight of the dry sieve. A sieve 8 inches in diameter is used 

for the equivalent of a No. 3 size can (404 x 700) and smaller and a sieve 12 

inches in diameter is used for containers larger than the equivalent of a No. 3 

size can.
United States Standards for Grades of Canned Mushrooms (May 20, 2019) 

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Table I

Minimum drained weight of canned mushrooms

Container Designation 

(metal, unless otherwise 

stated)

Container size overall dimensions

Capacity weight 

H2O at 68°F

Minimum 

drained weight 

ounces 

(avoirdupois)

Diameter 

(inches)

Height (inches)

2 Z Mushroom 2-2/16 2-4/16 3.57 2.0

2-1/2 Z Glass — — 4.464 2.5

3 Z Mushroom 2-2/16 3-4/16 5.36 3.0

4 Z Mushroom 2-11/16 2-12/16 7.15 4.0

8 Z Mushroom 3 4 13.55 8.0

Jumbo 3-7/16 5-10/16 25.70 16.0

No. 10 6-3/16 7 109.45 68.0

Factors of Quality

§52.1488 Ascertaining the grade.

(a) The grade of canned mushrooms is ascertained by considering in conjunction 

with the requirements of the respective grade the respective ratings for the 

factors of color, uniformity of size and shape, defects, and character.

(b) The relative importance of each factor which is scored is expressed numerically 

on the scale of 100. The maximum number of points that may be given each 

such factor is:

Factors Points

Color 30

Uniformity of size and shape 20

Defects 30

Character 20

Total Score 100

(c) Normal flavor and odor means that the product is free from objectionable 

flavors and objectionable odors of any kind. 

§52.1489 Ascertaining the rating for the factors which are scored.

The essential variations within each factor which is scored are so described that the 

value may be ascertained for each factor and expressed numerically. The numerical 

range within each factor which is scored is inclusive (for example, 18 to 20 points

means 18, 19, or 20 points).
United States Standards for Grades of Canned Mushrooms (May 20, 2019)

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§52.1490 Color.

(a) “A” classification. Canned mushrooms that possess a good color may be 

given a score of 27 to 30 points. Good color means that the canned 

mushrooms possess a color that is practically uniform, bright, and typical of 

canned mushrooms produced from mushrooms of similar varietal characteristics 

and meet the following additional requirements for the respective color type:

(1) White or Cream. The color of the surface of the individual caps or 

portions thereof is not darker than medium cream, which color may 

possess a slight tannish cast that does not more than slightly affect the 

overall color appearance of the units, individually or collectively; and with 

respect to the styles of sliced buttons, sliced whole, random sliced whole, 

and stems and pieces, the color of gills of the sliced units is not darker 

than light tannish gray: Provided, That in sliced units the contrast in color 

between the gills and the surface of the cap of such sliced units does not 

more than slightly affect the overall color appearance of the product.

(2) Brown. The color of the surface of the individual caps is not darker than 

light brown, which color may possess a slight grayish cast that does not 

more than slightly affect the overall color appearance; and with respect to 

the styles of sliced buttons, sliced whole, random sliced whole, and stems 

and pieces, the color of the gills of the sliced units is not darker than 

medium brownish gray: Provided, That in sliced units the contrast in color 

between the gills and the surface of the cap of such sliced units does not 

more than slightly affect the overall color appearance of the product.

(b) “B” classification. Canned mushrooms that possess a fairly good color may be 

given a score of 24 to 26 points. Canned mushrooms that fall into this 

classification shall not be graded above U.S. Grade B, regardless of the total 

score for the product (this is a limiting rule). Fairly Good Color means that the 

canned mushrooms possess a color that is typical of canned mushrooms 

produced from mushrooms of similar varietal characteristics and that such color 

may be dull but not to the extent that the appearance of the product is seriously 

affected; and that the canned mushrooms meet the following additional 

requirements for the respective color types:

(1) White or Cream. The color of the surface of the individual caps may be 

dark cream, which color may possess a gray or brown cast that does not 

seriously affect the overall color appearance of the product; and with 

respect to the styles of sliced buttons, sliced whole, random sliced whole, 

and stems and pieces, the color of the gills of the sliced units is not darker 

than tannish gray: Provided, That in sliced units the contrast in color 

between the gills and surface of the cap of such sliced units does not 

seriously affect the overall color appearance of the product.
United States Standards for Grades of Canned Mushrooms (May 20, 2019)

7

(2) Brown. The color of the surface of the individual caps may be medium 

brown in color which color may possess a grayish cast that does not 

seriously affect the overall color appearance of the product, and with 

respect to the styles of sliced buttons, sliced whole, random sliced whole, 

and stems and pieces, the color of the gills of the sliced units may be dark 

brownish gray: Provided, That in sliced units the contrast in color between 

the gills and surface of the cap of such sliced units does not seriously 

affect the overall color appearance of the product.

(c) “SStd” classification. Canned mushrooms that fail to meet the requirements of 

paragraph (b) of this section may be given a score of 0 to 23 points and shall not 

be graded above Substandard, regardless of the total score for the product (this 

is a limiting rule).

§52.1491 Uniformity of size and shape.

(a) General. The factor of uniformity of size and shape for the style of stems and 

pieces of canned mushrooms is not scored; the other three factors (color, 

defects, and character, as applicable are scored and the total multiplied by 100 

and divided by 80, dropping any fractions to determine the total score.

(b) Definitions of terms.

(1) Diameter. The diameter of a cap in the styles of whole, buttons, sliced 

whole mushrooms, and sliced buttons means the greatest width of the cap 

when measured parallel with the under side of the cap.

(2) Center slice. Center slice in the styles of sliced buttons and sliced whole 

mushrooms means a unit sliced from a mushroom button or from a whole 

mushroom approximately parallel to the longitudinal stem axis; possesses 

two cut surfaces; and measures more than 1/2 inch in the longest 

dimension.

(3) Small side-slice. Small side-slice in the styles of sliced buttons, sliced 

whole mushrooms, and random sliced whole mushrooms means a slice 

without attached stem or portion of stem; which possesses only one cut 

surface; and which measures 1/2 inch or less in the longest dimension.

(c) “A” classification. Except in the style of stems and pieces, canned mushrooms 

that are practically uniform in size and shape may be given a score of 18 to 20 

points. Practically uniform in size and shape has the following meanings with 

respect to the applicable styles of canned mushrooms:

(1) Whole; buttons. The units are practically uniform in shape; the stems are 

cut transversely; and the diameter of the cap with the largest diameter 

does not exceed the diameter of the cap with the smallest diameter by 

more than 1/4 inch; and of all the units in the container, in the 85 percent, 
United States Standards for Grades of Canned Mushrooms (May 20, 2019)

8

by count, with the most uniform diameters, the diameter of the cap with 

the largest diameter does not exceed the diameter of the cap with the 

smallest diameter by more than 1/8 inch.

(2) Sliced whole mushrooms, sliced buttons. The presence of irregularshaped units does not materially affect the appearance of the product; not 

more than 5 percent, by weight, of the units may be small side-slices; and 

the diameter of the center slice with the largest diameter does not exceed 

the diameter of the center slice with the smallest diameter by more than 

3/8 inch.

(3) Random sliced whole mushrooms. Not more than 5 percent, by weight, 

of all the units may be small side-slices.

(d) “B” classification. Except in the styles of stems and pieces, canned 

mushrooms that are fairly uniform in size and shape may be given a score of 16 

or 17 points. Fairly uniform in size and shape has the following meanings with 

respect to the applicable styles of canned mushrooms;

(1) Whole; buttons. The units are fairly uniform in shape; the stems are cut 

transversely; and of all the units in the container, in the 85 percent, by 

count, with the most uniform diameters, the diameter of the cap with the 

largest diameter does not exceed the diameter of the cap with the smallest 

diameter by more than 1/4 inch.

(2) Sliced whole mushrooms; sliced buttons. The presence of irregular 

shaped units does not seriously affect the appearance of the product; not 

more than 10 percent, by weight, of the units may be small side-slices; 

and the diameter of the center slice with the largest diameter does not 

exceed the diameter of the center slice with the smallest diameter by more 

than 5/8 inch.

(3) Random sliced mushrooms. Not more than 10 percent, by weight, of 

the units may be small side-slices.

(e) “SStd” classification. Canned mushrooms that fail to meet the requirements of 

paragraph (d) of this section may be given a score of 0 to 15 points. Canned 

mushrooms that fall into this classification shall not be graded above U.S. Grade 

B, regardless of the total score for the product (this is a partial limiting rule).

§52.1492 Defects.

(a) General. The factor of defects refers to the degree of freedom from units which 

are crushed or broken, damaged, or seriously damaged.
United States Standards for Grades of Canned Mushrooms (May 20, 2019)

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(b) Definitions of terms.

(1) Crushed or broken unit with respect to all styles other than the style of 

stems and pieces means a unit that is crushed to the extent so as to 

destroy its normal shape or that is severed into two or more separate 

parts.

(2) Damaged means damaged by discoloration, pathological injury, 

mechanical injury, or damaged by other means to such an extent that the 

appearance or eating quality of the unit is materially affected. Knife marks 

resulting from the preparation of sliced whole mushrooms, random sliced 

whole mushrooms, or sliced buttons are not considered mechanical injury.

(3) Seriously damaged means damaged to such an extent that the 

appearance or eating quality of the unit is seriously affected.

(c) “A” classification. Canned mushrooms that are practically free from defects 

may be given a score of 27 to 30 points. Practically free from defects means:

(1) The product does not exceed the applicable allowances prescribed for the 

respective type of defect in Table II of this section; and

(2) Notwithstanding the specified allowances, the presence of crushed or 

broken units in the applicable styles, damaged, and seriously damaged 

units does not materially affect the appearance or eating quality of the 

product.

(d) “B” classification. Canned mushrooms that are fairly free from defects may be 

given a score of 24 to 26 points. Canned mushrooms that fall into this 

classification shall not be graded above U.S. Grade B, regardless of the total 

score for the product (this is a limiting rule). Fairly free from defects means:

(1) The product does not exceed the applicable allowances prescribed for the 

respective type of defect in Table II of this section; and

(2) Notwithstanding the specified allowances, the presence of crushed or 

broken units in the applicable styles, damaged, and seriously damaged 

units does not seriously affect the appearance or eating quality of the 

product.

(e) “SStd” classification. Canned mushrooms that fail to meet the requirements of 

paragraph (d) of this section may be given a score of 0 to 23 points and shall not 

be graded above Substandard, regardless of the total score for the product (this 

is a limiting rule).
United States Standards for Grades of Canned Mushrooms (May 20, 2019) 

10

Table II

Summary of allowances for defects

Grade Classification

Maximum allowances

All styles except 

Stems and Pieces All styles

Crushed or broken Damaged Seriously damaged1

A 5% by weight 5% by weight including 1% by weight

B 10% by weight 10% by weight including 2% by weight

SStd Fails to meet foregoing requirements for Grade B classification

1 One unit in a container is permitted to be seriously damaged: Provided, That the total number of such seriously damaged units 

in all of the containers comprising the sample is within the percentage permitted for such defect.

§52.1493 Character.

(a) General. The factor of character refers to the tenderness and texture of the 

canned mushrooms and the development of the cap in the styles of Whole and 

Buttons. 

(b) Definitions of closed veil. Closed veil means that the membrane which 

extends from the inner edge of the cap to the stem practically covers the gills.

(c) “A” classification. Canned mushrooms that possess a good character may be 

given a score of 18 to 20 points. Good character means that the units are firm 

and tender; the product is practically free from fibrous or rubbery units; and that 

with respect to the styles of Whole and Buttons not less than 95 percent, by 

weight, of all the units possess closed veils. One unit which fails to meet the 

requirements for closed veils in the styles of Whole and Buttons is permitted in a 

container: Provided, That the average for such units in all the containers 

comprising the sample does not exceed 5 percent, by weight.

(d) “B” classification. Canned mushrooms that possess a fairly good character 

may be given a score of 16 or 17 points. Canned mushrooms that fall into this 

classification shall not be graded above U.S. Grade B, regardless of the total 

score for the product (this is a limiting rule). Fairly good character means that 

the units are reasonably tender; may be slightly soft; the product is reasonable 

free from fibrous or rubbery units; and that with respect to the styles of Whole 

and Buttons is permitted in a container: Provided, That the average for such 

units in all the containers comprising the sample does not exceed 10 percent, by 

weight.

(e) “SStd” classification. Canned mushrooms that fail to meet the requirements of 

paragraph (d) of this section may be given a score of 0 to 15 points and shall not 

be graded above Substandard, regardless of the total score for the product (this 

is a limiting rule).
United States Standards for Grades of Canned Mushrooms (May 20, 2019) 

11

Lot Inspection and Certification

§52.1494 Ascertaining the grade of a lot.

The grade of a lot of canned mushrooms covered by these standards is determined by 

the procedures set forth in the Regulations Governing Inspection and Certification of 

Processed Fruits and Vegetables, Processed Products Thereof, and Certain Other 

Processed Food Products (7 CFR 52.1 through 52.83).

Score Sheet

§52.1495 Score sheet for canned mushrooms.

Size and kind of container

Container marks or identification

Label

Net weight (ounces)

Vacuum (inches)

Drained weight (ounces)

Style

Size

Color

Factors Score Points

Color 30 

“A” 27-30 

“B” 24-261

“Sstd” 0-231

Uniformity of size and shape 20

“A” 18-20

“B” 16-17

“Sstd” 0-152

Defects 30

“A” 27-30

“B” 24-261

“Sstd” 0-231

Character 20 

“A” 18-20 

“B” 16-171

“Sstd” 0-151

Total Score 100

Grade

Normal flavor and odor

1 Indicates limiting rule.

2 Indicates partial limiting rule.