Fumonisins are found in corn. The most common, fumonisin FB1 (FB1) is toxic to animals, disrupts sphingolipid metabolism, and is a suspected risk factor for neural tube defects (NTDs; serious birth defect) and cancer in humans that consume contaminated corn as a diet staple. FB1 levels in foods and animal feeds should therefore be reduced as much as possible. Quantification of FB1 in uncooked and cooked grits or corn combined with rodent bioassays utilizing FB1-specific toxicological endpoints were done to evaluate the effectiveness of extrusion and nixtamalization for reducing FB1 concentrations and toxicity. (A) Extrusion reduced (64-72%) FB1 concentrations in 2 batches of grits initially containing low (10 ppm) or high (50 ppm) amounts of FB1. Reductions improved to 89-94% when 10% glucose was added before cooking. No (low dose batch) or markedly reduced (high dose batch) kidney pathology and sphingolipid effects were found when extruded, glucose supplemented grits were fed (50% w/w in the diet) to rats for up to 8 weeks. Extrusion without glucose was less effective but none the less reduced toxicity. (B) Alkaline cooking whole kernel FB-contaminated corn (3 batches; initial FB1 concentrations of 1.8 – 4.2 ppm) reduced FB1 concentrations by about 90%. Kidney pathology and sphingolipid effects were absent (2 batches: FB1 diet concentrations about 0.1 ppm) or significantly reduced (1 batch; FB1 diet concentration 0.4 ppm) in rats fed the alkaline cooked corn. (C) Hydrolyzed FB1 (HFB1) is formed from FB1 during nixtamalization. Unlike FB1 (10 mg/kg body weight = 14 µmol/kg), doses up to 20 mg/kg (= 49 µmol/kg) body weight HFB1 did not cause NTDs when test using the LM/Bc mouse bioassay. Furthermore, FB1 caused liver pathology and significantly disrupted sphingolipid metabolism whereas only slight sphingolipid effects and no pathology were found in mice given HFB1. Together, these findings show that extrusion, especially with glucose supplementation, and nixtamalization effectively reduce the toxicity of FB1 contaminated corn.

Reduction of fumonisin toxicity by extrusion and nixtamalization (alkaline cooking)

251st National Meeting (2016)

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