Destruction of aflatoxins [Aspergillus flavus, Aspergillus parasiticus] in peanut protein isolates by sodium hypochlorite [Food decontamination]

Sodium hypochlorite has been tested for destruction of aflatoxins during the preparation of peanut protein isolates from raw peanuts and defatted peanut meal. The treatments were evaluated by determination of the aflatoxins in the products by thin layer chromatography. Effects of sodium hypochlorite concentration, reaction pH, temperature, and time were studied. Results show that both the sodium hypochlorite concentration and pH are important factors in reducing the concentration of aflatoxins in the protein isolates to nondetectable levels. The treatment with 0.4% sodium hypochlorite at pH 8 produced protein isolates with trace amounts of aflatoxins B1 and B2 from ground raw peanuts containing 725 ppb aflatoxin B1 and 148 ppb aflatoxin B2, whereas untreated protein isolates contained 384 ppb aflatoxin B1 and 76 ppb aflatoxin B2. At pH 9, 0.3% sodium hypochlorite reduced the aflatoxin B1 content in the protein isolates from 300 ppb to below detectable quantities and the aflatoxin B2 content from 52 ppb to 2 ppb. Similar results were obtained at pH 10 for 0.3% sodium hypochlorite concentration. In the case of defatted peanut meal which contained 136 ppb aflatoxin B1 and 36 ppb aflatoxin B2, 0.25% sodium hypochlorite concentration at pH 8 (0.20% at pH 9; 0.15% at pH 10) reduced both the aflatoxin B1 and B2 contents to below detectable quantities in protein isolates as compared to aflatoxin levels of ca. 75 ppb B1 and 17 ppb B2 in the untreated protein isolates. Reaction temperature and time did not affect the destruction of aflatoxins significantly.