Occurrence of Fungal Growth in the Traditionally Processed Cassava Produces in Lushoto, Rorya and Ukerewe Districts

Abstract

The study was conducted in Lushoto, Rorya and Ukerewe districts of Tanzania on cassava processing and drying methods; storage and fungal growth on cassava products. One hundred and twenty (120) households were interviewed on cassava processing and storage methods. Cassava products samples were collected for laboratory fungal growth analysis. ‘Udaga’ was the only final cassava product produced from cassava roots from all three districts. ‘Udaga’ is a cassava product traditionally produced by peeling cassava roots, solid fermented once or twice and direct or indirect sun-dried. Cassava products were fermented by either heaping under roof, or on rock surface, or on cemented floor, in ‘tenga’ and in polypropylene bags. ‘Tenga’ is a big busket made of bamboo-wood-sliced stems with holding capacity ranging from 10-50 kg. The whole fermentation process took 18 days. During fermentation, cassava was covered either by banana leaves, or tree leaves, or cassava peels, or old cloth, or cactus leaves, or polythene sheets and sometimes left uncovered. Cassava products were dried for 12-196 h indirectly or on direct sun. The cassava products were stored for less than one month (52.5%), 1-2 months (36.7%), 3-4 months (7.5%), and 5-6 months (3.3%). The storage methods/tools mostly used for storing cassava product for more than one month were polypropylene bags (28.3%), platform-like/under roof (15.0%) and plastic containers (4.2%). The study noted that traditional methods of cassava processing which included fermentation, produced poor quality (unhygienic) ‘udaga’ which was associated with fungal growth. The fungus Rhizopus spp. was the most prevalent (59.2%) followed by Cladosporium spp. (51.7%), Penicilium spp. (38.3%), Fusarium spp. (36.7%), Aspergillus spp. (20.0%) and yeast (10.8%). Other fungi observed were Curvularia spp. (4.2%) and Mucor spp. (4.2%). The study noted that traditional methods of cassava processing produced poor quality (unhygienic) ‘udaga’ in the study areas.

Keywords: Processing methods, cassava, storage methods, udaga