Degradation of aflatoxins in aqueous buffer in the presence of nucleophiles

Abstract

This study compared the efficacies of lysine, glycine and methylamine to mediate aflatoxin destruction in heated aqueous phosphate buffers. A 3 × 3 × 4 factorial design (buffer pH, heating temperature and nucleophile) was followed. The buffer was artificially contaminated ("spiked") with mixed aflatoxin standard and heated for specified time periods. After the heat treatment residual aflatoxins were determined using HPLC procedures. Aflatoxin reduction was influenced by the buffer pH and the pKa of the added nucleophile. When phosphate buffer (at pH 9) was heated to 150 °C the degradation rate constants (k) aflatoxin in the presence of lysine, glycine and methylamine were 0.11, 0.09 and 0.08 min-1 respectively. Addition of calcium chloride to the "spiked" buffer lowered aflatoxin reduction, but upon adding lysine or methylamine, aflatoxin reduction was restored to some extent. These findings demonstrate the potential capability of lysine to mediate aflatoxin reduction. © 2010 Elsevier Ltd.