Corn Grading Factors
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 GIPSA Official United States Standards for Grain 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).
Broken Corn & Foreign Material (BCFM)
Broken Corn & Foreign Material is part of the GIPSA Official United States Standards for Grain grading criteria. This test determines the amount of all 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 sieve. Foreign material is defined as all material passing through a 6/64th inch roundhole sieve and the coarse non-corn material retained on the 12/64th sieve. BCFM is reported as a percentage of the initial sample by weight.
Total Damage/Heat Damage
Total Damage is part of the GIPSA Official United States Standards for Grain grading criteria. A representative working sample of 250 grams of BCFMfree corn is visually examined by a properly trained individual for content of damaged kernels. Types of damage include blue-eye mold, cob rot, drier-damaged kernels (different from heat-damaged kernels), germ-damaged kernels, heat-damaged kernels, insect-bored kernels, mold-damaged kernels, moldlike substance, silk-cut kernels, surface mold (blight), surface mold, mold (pink Epicoccum), and sproutdamaged 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 is 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.
Moisture
The moisture recorded by the elevators’ electronic moisture meter at the time of delivery is reported. Electronic moisture meters sense an electrical property of grains called the dielectric constant that varies with moisture. The dielectric constant rises as moisture content rises. Moisture is reported as a percent of total wet weight.