Fate of the mycotoxin fumonisin B1 during alkaline cooking of cultured and whole kernel corn
Burns, Tantiana Donata
MetadataShow full item record
Fumonisins are Fusarium mycotoxins that are natural contaminants of corn. They are toxic to animals and consumption of contaminated foods, including tortillas, is a suspected risk factor for neural tube defects in humans. Nixtamalization, the alkaline cooking method for making tortillas from corn, reduces fumonisin concentrations in tortillas, however, its effect on in vivo fumonisin toxicity is not known. To determine if interactions between fumonisins and corn matrix components during nixtamalization affect toxicity, fumonisin B1 (FB1)-contaminated culture material (CM) or a CM–ground corn mixture (the ground corn provided corn matrix) were nixtamalized and their kidney toxicity compared in a three week rat feeding bioassay. Nixtamalization reduced the FB1 concentrations of CM 70% and of the CM-corn mixture 90%. Rats fed uncooked CM exhibited marked renal toxicity whereas a less severe effect was found in the rats fed nixtamalized CM, and no renal toxicity was evident in rats fed the nixtamalized CM-corn mixture. Results of this experimental model suggest that fumonisin-corn matrix interactions occur during nixtamalization and might contribute to reducing FB1 concentrations and toxicity. Nixtamalization in households and industry involves the alkaline cooking of whole kernel corn. In a second experiment, nixtamalization increased mycotoxin-matrix binding in two batches of fumonisin-contaminated whole kernel corn. Ten to 15% of the fumonisins were bound to the matrix after cooking, whereas < 5% was bound beforehand. Reduction of free (not bound) FB1 concentrations varied from 90% (batch 1) to 30% (batch 2). When equivalent amounts were mixed with rodent chow and fed to rats for three weeks, both the uncooked (9 ppm FB1 in the mixed diet) and nixtamalized corn kernels (4 ppm in the mixed diet) from batch 2 caused significant kidney toxicity indicating that fumonisin-matrix binding had a neglible effect on the toxic potential of the nixtamalized corn kernels. Therefore, the matrix binding did not significantly influence in vivo toxicity.