Reduction of aflatoxins in peanut meal by extrusion cooking in the presence of nucleophiles

This study explored the feasibility of degrading aflatoxins in contaminated peanut meal by extruding in the presence of calcium chloride with lysine and methylamine. A 2 × 2 × 3 experiment (moisture, pH and nucleophile) was designed to screen for a nucleophile to use in a study of extrusion conditions to degrade aflatoxins in peanut meal. The nucleophile was mixed with peanut meal at 2 g/100 g protein level and the samples “spiked” with aflatoxin standards. They were extruded using a single screw extruder, and aflatoxins quantified by HPLC.The presence of calcium chloride impeded the degradation of aflatoxins by extrusion. However, methylamine and lysine showed comparable efficacies to mediate aflatoxin reduction. There were significant (p ≤ 0.05) interactions between moisture and pH, as well as moisture and temperature. Contour plots from regression models (R2 = 0.85) showed a bimodal effect of moisture on aflatoxin degradation. Extrusion cooking reduced aflatoxins from an initial 417.72 μg/kg to 66.87 μg/kg (i.e. 84% reduction) in the peanut meal.