Fungal mycoflora and contamination of maize from Vietnam with aflatoxin B1 and fumonisin B1

Abstract

Twenty five samples of maize intended for human or animal consumption coming from North, Central and South Vietnam were analysed for fungal contamination and for the presence of aflatoxin B1 and fumonisin B1. The total fungal load was found to be greater in maize intended for animal feed than for human consumption with average levels of 4x106 and 7x105 CFU/g, respectively. Identification of fungal strains revealed that Aspergillus was the most frequent genus, found in all maize samples whatever their intended use or their geographic origin. Among the Aspergillus species, A. flavus was the most frequent contaminant, observed in more than 90% of the samples. Other fungal strains found in the Vietnamese maize samples belonged to Penicillium species, Fusarium verticillioides and to the Mucorales, and were found in up to 53, 33 and 23% of the samples, respectively. All samples were tested for both aflatoxin and fumonisin contamination. Aflatoxin B1 was found in 17 samples (68%). Five of these samples showed aflatoxin B1 levels below 10 µg/kg, ten samples were found to be contaminated in a range of 11.3 to 47.2 µg/kg, and 2 samples showed contamination levels of 98.4 and 126.5 µg/kg, respectively. The maize samples for human consumption were found frequently contaminated with aflatoxin B1 (77%), but the level of contamination was lower than those for animal consumption. Fumonisin B1 contamination was found in 8 out of 25 samples (32%). Detected amounts of fumonisin B1 ranged from 0.4 to 3.3 mg/kg.