TEST DESCRIPTIONS FOR THE ISU GRAIN QUALITY LABORATORY

Near-infrared Composition & Density:

Composition of corn (moisture, protein, oil, starch, and density) and
soybeans (moisture, protein, oil, and fiber) determined by NIR instruments
calibrated by ISU GQL methods developed by ISU GQL.

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NIR Amino Acid Analysis (Soybeans):

Amino acid profile (5 essential amino acids) predicted by NIR instruments calibrated by ISU GQL
methods developed by ISU GQL.

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NIR Fatty Acid Analysis (soybeans):

Fatty acid profile predicted by NIR instruments calibrated by ISU GQL
methods developed by ISU GQL.

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Density by Pycnometer:

The Pycnometer is an instrument that measures specific gravity of materials.
Density is measured in units of grams per cubic centimeter (g/cc).
ISU GQL uses these densities as a reference value for our NIR corn density calibration.

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Breakage Susceptibility:

A test to determine breakage susceptibility during handling and transportation.
200 grams of corn are weighted out and processed through a Wisconsin breakage
tester and the processed grain is screened through a 16/64 screen. Those particles
that pass through the screen are weighed. The results are expressed as a
percentage of broken kernels.

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Seed Weight:

Seed weight (grams per 1,000 seeds) is sometimes an
important factor for food use grains. It is determined by using an automated seed
counter. That passes seeds individually through a photoelectric counting beam.

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Test Weight:

All grains. Results are in pounds per bushel. Grains are funneled into an approved
dry quart measure, leveled off, and weighed.

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Thins (corn size test):

Corn is screened with a 20/64 screen. The grains pass through the screen
are called thins. The results are expressed as a percentage of thins. Thins are used by
dry corn millers to identify undesireable samples.

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Amino Acid Profile by Wet Chemistry:

Amino acid profile is determined by approved HPLC methods. Results are
expressed as a percentage of total weight.

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Fatty Acid Profile by Wet Chemistry:

Fatty Acid profile is determined by approved GC methods. Results are
expressed as a percentage of toal oil.

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Stress Cracks:

Corn kernels are placed on a light table. The grain is separated according
to visible cracks showing while on the light table. Results are expressed
as a percentage of stress cracks.

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U.S. Grain Grade:

Samples are sent to a licensed grain grader for determination of factors in the
Official Grades.

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Copyright © 2004 Grain Quality Laboratory, Iowa State University, Ames, Iowa