The effect of village processing techniques on the content of aflatoxins in corn and peanuts in Zambia

Abstract

The effect of village processing techniques on the aflatoxin content of corn and peanut products was investigated. In 30 trials, corn kernels were dehulled (bran removal), soaked for 24 h, washed and dried before grinding into flour and boiling in water to a thick consistency (Nshima). Shelled peanuts were either dry-roasted as whole kernels or ground into peanut meal and cooked. Dehulling, following by 24-h soaking (steeping) and subsequent washing significantly (P < 0.05) reduced the aflatoxin B1 content of corn flour from 900 to 150 micrograms kg-1, and similarly that of aflatoxin G1 from 929 to 114 micrograms kg-1. Preparation of Nshima did not result into a substantial reduction in aflatoxin content, neither did extension of the cooking duration of 2 h afford any further decontamination. Whereas boiling peanut meal yielded a moderate reduction in the content of aflatoxins B1 and G1, roasting whole peanut kernels greatly reduced (P < 0.001) the concentrations of the toxins from that in raw kernels (AFB1 = 8600 micrograms kg-1 and AFG1 = 6200 micrograms kg-1) to 1300 and 1200 micrograms kg-1, respectively. These results indicate that specific processing techniques carried out in Zambian villages are effective in reducing aflatoxin carry-over into edible fractions, while others are not.