Natural occurrence of AFB1 in maize and effect of traditional maize flour production on AFB1 reduction in Malawi.

Abstract

Aflatoxin B1 (AFB1) is one of the most harmful mycotoxins to humans, animals, and crops that result in illnesses and economic losses. Maize, the most important staple food in most southern African countries, is susceptible to these fungi infections throughout its growth, harvest, transport and storage. In this study, we report on the incidence of AFB1 (determined by indirect competitive ELISA) contamination in maize from Malawi and the effect of traditional maize-flour production procedures on the final AFB1 levels. AFB1 was detected in 45.3% of the maize samples with 12.3% of them exceeding 5 µg/kg (FAO median AFB1 MTL). The traditional flour production procedures reduced AFB1 significantly in the order: soaking of dehulled maize (72.4±5.4, 75.4±3.5 and 80.9±5.3% for 24, 48 and 72 h soaking periods, respectively) > dehulling of maize (mean 29.3±5.4%) > sun drying (11.7% max). Sun drying followed pseudo-first order kinetics in AFB1. A maximum AFB1 reduction of 88.1 ± 3.1% was achieved using a sequence of dehulling, soaking for 72 h and sun drying the flour for 4.5 h. Key words: Aflatoxin B1, maize, Malawi.