Corn Grading Procedures: Part 1

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.

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 ground-damaged, badly weather-damaged, diseased, frost-damaged, germdamaged, germdamaged, heat-damaged, insect-bored, molddamaged, 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 roundhole sieve after sieving 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 that 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 that are 5/32 inch from center to center. The perforations of each row shall be staggered in relation to the adjacent row.