Degradation of aflatoxins and tocopherols in peanut (Arachis hypogaea): Effect of aflatoxin type, time and temperature of roasting

At the present time, aflatoxins are believed as one of the most harmful mycotoxins to people, and nuts including peanuts are one of the main foods for human exposure to mycotoxins. The aim of this study was to consider the effect of roasting conditions on the extent of the degradation of aflatoxins and nutritional changes (e.g., to the α- and γ-tocopherols) of peanuts. Samples of peanuts were contaminated with three initial concentrations of 2.5, 5 and 10 ng/g aflatoxin B1, B2, G1 and G2, respectively and the peanuts were roasted at 120 and 150 °C for 20, 30 and 40 min. Then, the concentrations of aflatoxins B1, B2, G1 and G2 were determined by High Performance Liquid Chromatography (HPLC) and the residual concentrations of the aflatoxins were expressed as percentage of the original aflatoxin content. In addition, the amount of tocopherols was determined by HPLC. The results showed that at highest decrements of the aflatoxins occurred at the higher roasting times, temperatures and initial concentrations of the aflatoxins. Accordingly, maximum reduction of aflatoxins B1, B2, G1 and G2 i.e., 37.9%, 39.8%, 37.4% and 40.4%, respectively, occurred when the contaminated samples with initial aflatoxin concentrations 10 ng/g were heated at 150 °C for 40 min. In addition, the content of α- and γ-tocopherols were increased at both roasting temperatures (120 and 150 °C) during the initial steps of the roasting process, however the roasting time increase up to 40 min, the amount of tocopherols decreased slightly. Thus, treatment of 150 °C for 40 min, could be regarded as the best roasting treatment for peanuts.