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Postharvest Pathology and Mycotoxins

Fungal Growth, Aflatoxin Production, and Moisture Equilibration in Mixtures of Wet and Dry Corn. D. B. Sauer, U.S. Department of Agriculture, Science and Education Administration, U.S. Grain Marketing Research Laboratory, Kansas State University, Manhattan 66506; R. Burroughs, Department of Grain Science & Industry, Kansas State University, Manhattan 66506. Phytopathology 70:516-521. Accepted for publication 14 November 1979. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/Phyto-70-516.

Yellow and white corn with initial moisture contents (MC) ranging from 11 to 26% were blended in various combinations and proportions to give average MC’s between 15 and 18%. The 20 blends were lightly inoculated with Aspergillus flavus and stored in plastic bags at 28 C. Moisture equilibration was rapid between the wet and dry corn fractions, and was more than 80% complete within 24 hr. In blends with mean MC of about 17.5% and equilibrium relative humidity (ERH) of 86–87%, A. flavus grew rapidly and produced aflatoxin. Blends with ERH below 85% generally had limited A. flavus growth and no aflatoxin; blends with average MC below 17% were invaded primarily by the A. glaucus group. Penicillium invaded most of the corn above 16% MC. Findings emphasized the importance of small differences in MC in determining safe storage conditions. The rapid moisture equilibration between wet and dry corn indicated that corn could be blended with minimal risk of mold damage or aflatoxin contamination if the average MC of the blend is low enough to prevent mold growth.