INFLUENCE OF MOISTURE-CONTENT AND STORAGE-TEMPERATURE ON THE PRODUCTION OF AFLATOXIN BY ASPERGILLUS-FLAVUS EA-81 IN MAIZE AFTER EXPOSURE TOGAMMA-RADIATION

The effect of gamma radiation on aflatoxin production by Aspergillus f lavus EA-81 in maize with different initial moisture levels was determ ined over a 15-day period. The viability of A. flavus on maize decreas ed over time with increasing moisture contents and storage at 8C. Afte r 45 days at 28C, levels of viable conidiospores of A. flavus increase d from 4.5 x 10(7) to about 3.0 x 10(8) per gram of maize. Levels of a flatoxin B-1 produced by A. flavus were 10 mu g kg(-1) in the maize st ored at 8C after 45 days. Production of aflatoxin was highest at 40% m oisture and 28C. Irradiation of 1.0 or 2.0 kGy greatly reduced the lev el of mold growth relative to unirradiated controls. A dose of 4.0 kGy eliminated all viable fungi. Aflatoxin B-1 production decreased with increased levels of irradiation and was negligible at 4.0 kGy. When ma ize was inoculated after irradiation and stored, the spore counts and aflatoxin levels were higher than in unirradiated and inoculated contr ols after 30 days. Apparently, the natural competitive microflora prev ented growth and thus limited higher concentrations of aflatoxin in ma ize.