Incidence of aspergillus flavus in stored dried cassava products and its association with aflatoxin production
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Date
2014
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Sokoine University of Agriculture
Abstract
Udaga is derivative of cassava products traditionally produced by farmers through peeling, fermentation and direct or indirect sun-drying of fermented cassava roots and widely consumed in Tanzania. The study was conducted in Lushoto, Rorya and Ukerewe districts in Tanzania based on diverse processing and storage methods between October and November 2012. Households (120) were interviewed on cassava processing and storage practices. Samples of dried cassava products were also obtained from interviewed households for moisture content, pH, microbial growth and aflatoxin content analysis. The factors that impact on mould and aflatoxin contamination of these products were established using regression analysis. Cassava products contained mean moisture content of 13.9%, pH 5.5 and aflatoxin ≥ 4 ppb in 8 samples. Mould incidence were Rhizopus spp. (59.17%), Cladosporium spp. (51.67%), Penicillium spp. (38.33%), Fusarium spp. (36.67%) Aspergillus spp. (20%) and Mucor spp. (4.17%). Aspergillus flavus was the most aflatoxin producing fungus isolated and occurred on 16.7% of all samples. Surface drying of cassava root pieces on bare ground rock surface, polypropylene sheet, rusty iron corrugated sheet roof and spread under roof (indirect sun drying) were some factors which were related to aflatoxin contamination. Other factors were fermentation of cassava products on rock surface, in polypropylene bags, heap under roof, heap on floor and cover with polypropylene bags/sheet, banana leaves, cassava peels and tree leaves. Storage practice positively significant correlated with aflatoxin contamination where cassava products were heaped under roof and stored in polypropylene bags.
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Keywords
Stored dried cassava products, Aflatoxin production, Aspergillus flavus, Fermented cassava roots