Fungal population and distribution of aflatoxigenic fungi in commercial almond powder products

The fungal population and distribution of aflatoxin-producing fungi in 30 samples of imported almond powder products purchased from retail markets were examined in this study. Total counts of fungi ranged from under 1.0 x 10 colony-forming units (CFU)/g to 8.5 x 10(3) CFU/g as determined with the dilution plating technique. The predominant fungi in the mould-contaminated almond samples were Aspergillus niger, A. flavus and the related species, Penicillium, Cladosporium and Rhizopus. Aflatoxin-producing ability in the isolates of A. flavus and related fungi were tested by thin layer chromatography using 2% yeast extract and 15% sucrose broth culture. Four different aflatoxigenic fungi were detected in the isolates; aflatoxins B1 and B2 were produced by some strains of A. flavus and A. parvisclerotigenus, and aflatoxins B1, B2, G1, G2 were produced by all tested strains of A. parasiticus and A. nomius. Identification of the strains was based on morphological and metabolic characters.