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ARS-Adapted Grain Sorter Sees Fungal Poisons Under "New Light"

January 13, 2004

By Erin Kendrick-Peabody

Source: ARS News Service, Agricultural Research Service, USDA

Spotting the fungal toxins contaminating kernels of harvested corn just became easier. An Agricultural Research Service engineer, through the use of near-infrared spectroscopy, has transformed a standard grain sorter into a fast and highly effective detector of the mycotoxins that cost the corn industry millions of dollars each year.

Mycotoxins are natural--yet potentially toxic--compounds produced by some fungi. Occurring on corn, cottonseed, wheat and other crops, they can cause serious illness in animals and livestock and are considered carcinogenic to humans.

Thomas C. Pearson adapted a commercially available grain sorter to detect two types of mycotoxins that commonly infest corn: aflatoxin, which is produced by some strains of the fungus Aspergillus flavus, and fumonisin, produced by fungi of the genus Fusarium.

Pearson found that two bands of infrared light are needed to detect almost all kernels of corn contaminated with alflatoxin and fumonisin. He equipped a grain sorter with a pair of filters corresponding with these wavelengths. The grain sorter is manufactured by Satake USA Inc. of Houston, Texas.

With just one pass through the sorting machine, 80 percent or more of the aflatoxin and fumonisin in commercially grown and harvested corn can be detected and removed. The sorter erroneously rejects less than 5 percent of uncontaminated corn, compared to error rates of 10 percent or higher for other sorting machines.

Pearson and his colleagues at the ARS Grain Marketing and Production Research Center in Manhattan, Kan., cooperated with ARS scientists in Peoria, Ill., to investigate the use of near-infrared for detecting fungal toxins. Peoria scientists provided the fungi-infected corn kernels for the studies.

The new method, which can process 260 bushels of corn per hour, can be used to segregate individual corn kernels before they are used for food or feed purposes.

Upcoming studies will look at how the machine can be calibrated to detect mycotoxins on white corn intended for human consumption and on wheat.

ARS is the U.S. Department of Agriculture's chief scientific research agency.