Reduction of aflatoxins during brewing of a Malawian maize-based non-alcoholic beverage, thobwa.

Abstract

This study reportsonthe effect of various production steps on levelsofaflatoxins during preparation of thobwa, a traditional maize-based fermented non-alcoholic beverage, brewed across Malawi. The effect of boiling, fermentation and their interaction on the level of aflatoxins, the trends of aflatoxin reduction during brewing, and the distribution of aflatoxins between the solid and liquid phases of the beverage were studied using VICAM AflaTest immunoaffinity fluorometric assay. Fermenting and boiling thobwapre-mix-, with initial aflatoxin content of 45-183 μg/kg, resulted in aflatoxin reduction of 47% (13-61 μg/kg)onaverage. Fermentation and boiling contributed about 20 and 33% aflatoxin reduction, respectively, but without interactive effect between the two factors. Fermenting the thobwafor 24 h led to further reduction of aflatoxins to about 37%oftheinitialcontent, andremainedconstant for up to 8 days.Thobwa is a popular beverage in Malawi which is consumed in large quantities by all gender categories including infants, therefore the presence of aflatoxins may constitute a significant health risk factor. This study highlights the need to use raw materials with low levels of aflatoxins for production of maize-based non-alcoholic beverages to ensure consumer safety.