Occurrence of Fusarium Species and Mycotoxins in Nepalese Maize and Wheat and the Effect of Traditional Processing Methods on Mycotoxin Levels

Abstract

Maize (Zea mays) and wheat (Triticum aestivum) collected in the foothills of the Nepal Himalaya Mountains were analyzed for Fusarium species and mycotoxins: fumonisins, nivalenol (NIV), and deoxynivalenol (DON). Predominant species were Gibberella fujikuroi mating population A (F. moniliforme) in maize and F. graminearum in maize and wheat; G. fujikuroi mating population D (F. proliferatum), F. acuminatum, F. avenaceum, F. chlamydosporum, F. equiseti, F. oxysporum, F. semitectum, and F. torulosum were also present. Strains of G. fujikuroi mating population A produced fumonisins, and strains of F. graminearum produced NIV or DON. By immunoassay or high-performance liquid chromatography, fumonisins were >1000 ng/g in 22% of 74 maize samples. By immunoassay or fluorometry, NIV and DON were >1000 ng/g in 16% of maize samples but were not detected in wheat. Fumonisins and DON were not eliminated by traditional fermentation for producing maize beer, but Nepalese rural and urban women were able to detoxify contaminated maize by hand-sorting visibly diseased kernels. Keywords: Fusarium; maize; wheat; mycotoxins; fumonisins; nivalenol; deoxynivalenol; HPLC; immunoassay