Toxigenic Aspergillus section Flavi and aflatoxins in Dried Yam Chips in Oyo State, Nigeria

Abstract: The distribution of aflatoxigenic Aspergillus and quantity of aflatoxins were determined in 40 dried yam chip samples collected from four markets in Ibadan, Nigeria. A control chip was prepared to assess the influence of storage duration on toxin accumulation. Two hundred and thirty-four isolates of the Aspergillus section Flavi group were recovered from 92.5% of the chips. A. flavus L-strain was the most occurring taxon (>60% incidence) while S BG strain and A. parasiticus were the least predominant (<4.5% incidence). The relative proportion of toxigenic to atoxigenic strains varied across markets with significant (P<0.05) incidence of atoxigenic over toxigenic in 75% of the locations. The overall incidence for B-and G-aflatoxin contamination was 97.5% with aflatoxin B 1 having the highest concentration of 190µg/kg. About 67.5% of the chip samples violated the EC regulation on aflatoxin levels in food. Consequently, contaminating mould and toxin reduction strategies targeted towards the post-production storage methods should be considered since there was the highest positive correlation (r=0.99) for the influence of storage duration on aflatoxin concentration in the contaminated samples. This will ensure public health safety