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

Authors: Voss, Kenneth; Meredith, Filmore; Bacon, Charles

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2003
Publication Date: 7/31/2003
Citation: Voss, K.A., Meredith, F.I., Bacon, C.W. 2003. The effect of baking and frying on the in vivo toxicity to rats of cornmeal containing fumonisins. Journal of Agricultural and Food Chemistry. v.51. n.18 p.5546-5551.

Interpretive Summary: Fumonisins are toxins made by fungi that grow on corn. Under some conditions, baking, frying or other cooking methods appear to decrease the amount of fumonisins in cooked foods. However, the fate of fumonisins in the cooked products is poorly understood. It is therefore possible that the fumonisins are not degraded, but become undetectable due to reversible chemical reactions that occur during cooking. There is also concern that some unknown, and therefore unmeasurable, toxic fumonisin breakdown products might form. A bioassay was done to address these questions. We baked cornbread, pan-fried corncakes, and deep-fried corn fritters using fumonisin-contaminated cornmeal. The cooked products were then fed to rats. By comparing the type and severity of the toxic effects found in the rats fed cornbread, corncakes and fritters to those found in rats fed uncooked contaminated cornmeal, it was shown that baking, pan-frying, and deep-frying had essentially no affect on toxicity. Likewise, baking and frying had little to no effect on the amount of fumonisins measured in the cooked products by routine analysis methods. These results are important because they show that significant amounts of undetectable fumonisins or unknown toxins did not form when fumonisin-contaminated cornmeal is baked or fried.

Technical Abstract: Fumonisins are mycotoxins produced by Fusarium verticillioides 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 Fusarium verticillioides culture material (CM). The cooked materials and the uncooked CM-spiked cornmeal were fed to groups of male rats 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) was slightly, but not significantly (p<0.05) lower than those of the 20% w/w baked cornbread (132.2 ppm), deep fried fitter (120.3 ppm) and CM-spiked cornmeal (130.5 ppm) 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