United States Department of Agriculture

Agricultural Marketing Service

Federal Grain Inspection Service

U.S. Standards September 1996

Distribution: FGIS, OSP, Industry Originating Office: FMD PPMAB

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Subpart D -- United States Standards for Corn

Contents

Subpart D -- United States Standards for Corn 1

Terms Defined 2

Principles Governing the Application of Standards 3

Grades and Grade Requirements 3

Special Grades and Special Grade Requirements 3
Official US Standards for Grain

Corn

September 1996

Page 2

Terms Defined

§ 810.401 Definition of corn.

Grain that consists of 50 percent or more of whole kernels of shelled dent corn and/or

shelled flint corn (Zea mays L.) and not more than 10.0 percent of other grains for which

standards have been established under the United States Grain Standards Act.

§ 810.402 Definition of other terms.

(a) Broken corn. All matter that passes readily through a 12/64 round-hole sieve and 

over a 6/64 round-hole sieve according to procedures prescribed in FGIS instructions.

(b) Broken corn and foreign material. All matter that passes readily through a 12/64

round-hole sieve and all matter other than corn that remains in the sieved sample after

sieving according to procedures prescribed in FGIS instructions.

(c) Classes. There are three classes for corn: Yellow corn, White corn, and Mixed corn.

(1) Yellow corn. Corn that is yellow-kerneled and contains not more than 5.0 percent of

corn of other colors. Yellow kernels of corn with a slight tinge of red are considered

Yellow corn.

(2) White corn. Corn that is white-kerneled and contains not more than 2.0 percent of

corn of other colors. White kernels of corn with a slight tinge of light straw or pink color

are considered White corn.

(3) Mixed corn. Corn that does not meet the color requirements for either of the classes

Yellow corn or White corn and includes white-capped Yellow corn.

(d) Damaged kernels. Kernels and pieces of corn kernels that are badly grounddamaged, badly weather-damaged, diseased, frost-damaged, germ-damaged, heatdamaged, insectbored, mold-damaged, sprout-damaged, or otherwise materially 

damaged.

(e) Foreign material. All matter that passes readily through a 6/64 round-hole sieve and

all matter other than corn that remains on top of the 12/64 round-hole sieve according to

procedures prescribed in FGIS instructions.

(f) Heat-damaged kernels. Kernels and pieces of corn kernels that are materially

discolored and damaged by heat.

(g) Sieves.

(1) 12/64 round-hole sieve. A metal sieve 0.032 inch thick with round perforations

0.1875 (12/64) inch in diameter which are 1/4 inch from center to center. The

perforations of each row shall be staggered in relation to the adjacent row.

(2) 6/64 round-hole sieve. A metal sieve 0.032 inch thick with round perforations 0.0937

(6/64) inch in diameter which are 5/32 inch from center to center. The perforations of

each row shall be staggered in relation to the adjacent row.
Official US Standards for Grain

Corn

September 1996

Page 3

Principles Governing the Application of Standards

§ 810.403 Basis of determination.

Each determination of class, damaged kernels, heat-damaged kernels, waxy corn, flint

corn, and flint and dent corn is made on the basis of the grain after the removal of the

broken corn and foreign material. Other determinations not specifically provided for

under the general provisions are made on the basis of the grain as a whole, except the

determination of odor is made on either the basis of the grain as a whole or the grain

when free from broken corn and foreign material.

Grades and Grade Requirements

§ 810.404 Grades and grade requirements for corn.

Grade

Minimum test

weight per

bushel

(pounds)

Maximum limits of:

Damaged kernels Broken corn

and foreign

material

(percent)

Heat damaged

kernels

(percent)

Total

(percent)

U.S. No. 1

U.S. No. 2

U.S. No. 3

U.S. No. 4

U.S. No. 5

56.0

54.0

52.0

49.0

46.0

0.1

0.2

0.5

1.0

3.0

3.0

5.0

7.0

10.0

15.0

2.0

3.0

4.0

5.0

7.0

U.S. Sample Grade

U.S. Sample grade is corn that:

(a) Does not meet the requirements for the grades U.S. Nos. 1, 2, 3, 4, or 5; or

(b) Contains stones with an aggregate weight in excess of 0.1 percent of the sample weight, 2 or 

more pieces of glass, 3 or more crotalaria seeds (Crotalaria spp.), 2 or more castor beans (Ricinus 

communis L.), 4 or more particles of an unknown foreign substance(s) or a commonly recognized 

harmful or toxic substance(s), 8 or more cockleburs (Xanthium spp.), or similar seeds singly or in 

combination, or animal filth in excess of 0.20 percent in 1,000 grams; or

(c) Has a musty, sour, or commercially objectionable foreign odor; or

(d) Is heating or otherwise of distinctly low quality

Special Grades and Special Grade Requirements

§ 810.405 Special grades and special grade requirements.

(a) Flint corn. Corn that consists of 95 percent or more of flint corn.

(b) Flint and dent corn. Corn that consists of a mixture of flint and dent corn containing

more than 5.0 percent but less than 95 percent of flint corn.

(c) Waxy corn. Corn that consists of 95 percent or more waxy corn, according to

procedures prescribed in FGIS instructions