Purpose: This study assessed the occurrence of fungi in some traditionally fermented foods (TFF) and evaluated the toxigenic potential of the fungi isolated from the TFF.
Methods: Cluster sampling procedure was used to obtain 18 samples each of fermented maize gruel (FMG), fermented locust beans [FLB] and fermented melon (FM) from different markets in Southwest Nigeria. The fungal load of the samples was determined and macroscopic, microscopic and molecular identification of isolated fungi species was done. The potential of the fungi isolates to produce aflatoxins, deoxynivalenol, fumonisin, ochratoxin and zearalenone was determined using thin-layer chromatography.
Results: The mean fungal load of the FMG, FLB and FM samples were 8.0 x 103 CFU/ml, 9.4 x 103 CFU/g and 7.9 x105 CFU/g, respectively. A total of 164 fungal isolate from nine genera; Aspergillus, Penicillium, Fusarium, Rhizopus, Saccharomyces, Pichia, Mucor, Candida and Rhodotorula were identified from the samples. The most dominant fungi isolates in FM samples were A. flavus, A. parasiticus, F. verticillioides and P. rugolosum while S. cerevisiae was identified from all the FMG samples. A total of 99 potentially toxigenic isolates of Aspergillus (56), Penicillium (24) and Fusarium (9) species were recovered from the samples. All positive extracts for aflatoxin G1 and zearalenone had spots with retardation factors ranging from 39 - 41mm and 80 - 85 mm, respectively. Of all the Aspergillus species from the FLB isolates (23), only 65% were positive for aflatoxin B1 by giving a light blue fluorescence under ultraviolet light while 14% of the fungi extracts from the FM samples were positive for fumonisin B1 from F. verticillioides.
Significance: The TFF are unsafe for consumption due to high fungi load and the consequent presence of mycotoxigenic fungi.