Comparison of the ability of three Aspergillus strains to form aflatoxins on bakery products and on nutrient agar.

The growth of Aspergillus parasiticus NRRL 2999, A. parasiticus NRRL 3000 and A. flavus NRRL 3251 on whole wheat bread and on cake ('Rührkuchen') was compared and the formation of the aflatoxin B1, B2, G1, G2 and M2 on these substrates and, for purpose of comparison, on malt extract agar was determined. On cake the moulds grew better than on bread and formed the highest yields of aflatoxins. Malt extract agar was the most unfavourable substrate for toxin production. The ratio M1/B1 on bread and cake was in the order of 0.1-0.4 and was higher than the data reported for grains. The highest yields of aflatoxin B1 (1.0 micrograms/g) were produced by A. flavus NRRL 3251 on cake.