Mycology and spoilage of retail cashew nuts

Thirty-two samples of retail cashew nuts from Lagos, Nigeria were examined on two media. The pH values (5.1-6.3) of all the samples were conducive for fungal growth and mycotoxin production. Moisture content levels ranged between 4.1 and 6.8%. Fifteen samples had moisture contents up to or above 5.8%, the highest level estimated to be ‘safe' for the storage of the nuts. Fourteen fungal species, mostly toxigenic and belonging to 5 genera were isolated. Seven species were from genus Aspergillus, 3 from Penicillium, 2 from Rhizopus and one each from Mucor and Syncephalastrum. The most predominant isolates were: A. niger, A. restrictus, A. flavus, A. fumigatus and Aspergillus sp. The mean and range of total fungal counts (CFU/g) in samples were: 3,368 (180 to 16, 300). At acceptable fungal levels of 103 and 104/g, only 14 and 28 samples, respectively, were deemed fit for human consumption. All the species recovered induced detectable loss in weights of the milled nuts, though to varying extents and would be expected to cause considerable spoilage of the nuts. Key words: Cashew nut, Anacardium occidentale, fungal count, mycology, Aspergillus sp., Penicillium sp., spoilage. African Journal of Biotechnology Vol.2(10) 2003: 36