New Test for Aflatoxin-Fighting CornBy
Corn kernels may someday produce ample amounts of their own anti-fungal
compounds that prevent aflatoxin contamination when the grain is stored. When
the fungus Aspergillus flavus invades corn kernels, it produces
aflatoxin, a carcinogen.
ARS scientists are employing a new test to quickly identify anti-fungal
compounds naturally produced in corn kernels. The test involves growing the
fungus on a thin layer of nutrient medium suspended on a glass fiber disk in a
vial. Previous methods, which used more of the nutrient medium, required more
solvent to extract the toxin.
So far, Agricultural Research Service
chemist Robert A. Norton has identified a half-dozen promising aflatoxin
inhibitors, including alpha carotene and several other carotenoids--compounds
that impart yellow color to modern corn hybrids.
The new assay is a significant improvement over older, slower testing
methods. Scientists at the National Center for Agricultural Research Utilization
in Peoria, Ill., can now test up to 200 samples a week, and from a much wider
range of compounds. The research parallels efforts to breed corn that supports
less growth of the fungus.
In the United States, corn with more than 20 parts per billion (ppb) of
aflatoxin-- equivalent to just 1 ounce in 3,125 tons--is considered unfit for
feeding to animals that produce meat or milk for humans. Grain with more than 5
ppb can't be used for making food-grade corn products.
Details are in a story in the July issue of ARS' Agricultural Research
magazine. The story is also on the World Wide Web at:
Scientific contact: Robert A. Norton, USDA-ARS National Center for
Agricultural Utilization Research, 1815 N. University Street, Peoria, IL 61604;
phone (309) 681-6251, fax number (309) 681- 6693, e-mail