Inactivation of aflatoxin B1 in corn meal, copra meal and peanuts by chlorine gas treatment

More than 75% degradation of aflatoxin B1 (AFB1) was achieved after treatment of AFB1-spiked corn meal, spiked copra meal (the residue of the kiln-dried coconut kernels after mechanical expulsion of oil) and peanuts artificially infected with Aspergillus parasiticus, with 11, 16 and 35 mg chlorine gas per g meal or peanuts, respectively. At these chlorine gas treatment levels, extension of the exposure period of the corn meal and copra meal beyond 2.5 hr, and the peanuts beyond 1 day, did not increase the percentage degradation of AFB1. The mutagenicity of chlorine-treated copra meal and peanuts spiked with AFB1 was greatly reduced compared with untreated controls, as determined in Salmonella typhimurium strain TA98 in the presence of rat liver S-9 mix; the reduction in mutagenicity was found to be highly correlated with the reduction in AFB1 levels. Reactions of chlorine with AFB1 or constituents of the meals or peanuts did not appear to generate new mutagenic compounds. The moisture content of the meals and peanuts appeared to be an important factor affecting the degradation of AFB1 by chlorine gas.