A. Corn Grading Factors
1. Test Weight
Test weight is a measure of the quantity of grain required to fill a specific volume (Winchester bushel). Test weight is a part of the FGIS Official U.S. Standards for Corn grading criteria.
The test involves filling a test cup of known volume through a funnel held at a specific height above the test cup to the point where grain begins to pour over the sides of the test cup. A strike-off stick is used to level the grain in the test cup, and the grain remaining in the cup is weighed. The weight is then converted to and reported in the traditional U.S. unit, pounds per bushel (lb/bu).
2. Broken Corn and Foreign Material (BCFM)
Broken corn and foreign material (BCFM) is part of the FGIS Official U.S. Standards for Corn.
This test determines the amount of matter that passes through a 12/64th inch round-hole sieve and all matter other than corn that remains on the top of the sieve. Broken corn is defined as all material passing through a 12/64th inch round-hole sieve and retained on a 6/64th inch round-hole sieve. Foreign material is defined as all material passing through the 6/64th inch round-hole sieve and the coarse non-corn material retained on top of the 12/64th sieve. BCFM is reported as a percentage of the initial sample by weight.
3. Total Damage/Heat Damage
Total damage is part of the FGIS Official U.S. Standards for Corn grading criteria.
A representative working sample of 250 grams of BCFM-free corn is visually examined by a properly trained individual for content of damaged kernels. Types of damage include blue-eye mold, cob rot, dryer-damaged kernels (different from heat-damaged kernels), germ-damaged kernels, heat-damaged kernels, insect-bored kernels, mold-damaged kernels, mold-like substance, silk-cut kernels, surface mold (blight), surface mold, mold (pink Epicoccum), and sprout-damaged kernels. Total damage is reported as the weight percentage of the working sample that is total damaged grain.
Heat damage is a subset of total damage and consists of kernels and pieces of corn kernels that are materially discolored and damaged by heat. Heat-damaged kernels are determined by a properly trained individual visually inspecting a 250-gram sample of BCFM-free corn. Heat damage, if found, is reported separately from total damage.