Effect of baking and frying on the in vivo toxicity to rats of cornmeal containing fumonisins.

Fumonisins are mycotoxins produced by Fusarium verticillioides (=F. moniliforme) and other Fusarium species. They are found in corn and corn-based foods. Cooking decreases fumonisin concentrations in food products under some conditions; however, little is known about how cooking effects biological activity. Baked cornbread, pan-fried corncakes, and deep-fried fritters were made from cornmeal that was spiked with 5% w/w F. verticillioides culture material (CM). The cooked materials and the uncooked CM-spiked cornmeal were fed to male rats (n = 5/group) for 2 weeks at high (20% w/w spiked cornmeal equivalents) or low (2% w/w spiked cornmeal equivalents) doses. A control group was fed a diet containing 20% w/w unspiked cornmeal. Toxic response to the uncooked CM-spiked cornmeal and the cooked products included decreased body weight gain (high-dose only), decreased kidney weight, and microscopic kidney and liver lesions of the type caused by fumonisins. Fumonisin concentration, as determined by HPLC analysis, in the 20% w/w pan-fried corncake diet [92.2 ppm of fumonisin B(1) (FB(1))] was slightly, but not statistically significantly, lower than those of the 20% w/w baked cornbread (132.2 ppm of FB(1)), deep-fried fritter (120.2 ppm of FB(1)) and CM-spiked cornmeal (130.5 of ppm FB(1)) diets. Therefore, baking and frying had no significant effect on the biological activity or concentration of fumonisins in these corn-based products, and the results provided no evidence for the formation of novel toxins or "hidden" fumonisins during cooking.