Isolation of toxigenic Aspergillus flavus and evaluation of aflatoxins in “Burukutu”, sorghum fermented beverage sold in Akure, Nigeria

Abstract

The possible health threat accompanied with the ingestion of ‘Burukutu’, an alcoholic beverage made from fungal contaminated cereals grains calls for regular inspection. The study aimed at the isolation of toxigenic Aspergillus flavus and quantification of aflatoxins in‘Burukutu’ sold in Akure, Nigeria. The fungi associated with the samples were isolated and counted using standard microbiological methods. Aflatoxins were extracted from 64 samples using different solvents and analyzed with the aid of High Performance Thin-Layer Chromatography (HPTLC). The aflatoxins in the samples applied on pre-heated HPTLC plates were estimated under fluorescent UV light. Cooked fermented milled malted grains ‘Burukutu’ (CFMMG) had the highest fungal counts of 6.8×102 and 2.9×102 cfu/ml at 24 and 48 h of incubation respectively. The fungal isolates identified from the samples were: Aspergillus flavus, Fusarium solani, Rhizopusstolonifer, A. fumigatus, A. niger, Penicillumitalicum, Saccharomyces cerevisae and Candida krusei. All the analyzed samples showed varied quantity of aflatoxin concentrations. The overall quantification of aflatoxins G1, G2, B1 and B2 revealed significant reduction in end products ‘Burukutu’ when compared with the substrates from which it was made. Different general fungi associated with ‘Burukutu’ were identified. There was also a decline in the level of aflatoxins in ‘Burukutu’ which was a product of natural fermentation