Deterioration and spoilage of peanuts and desiccated coconuts from two sub-Saharan tropical East African countries due to the associated mycobiota and their degradative enzymes

A broad variety of fungi (84 species belonging to 36 genera) were identifie d with more taxa infesting peanut seed samples from two tropical countries (29 genera and 61 species) compared to those found in desiccated coconuts ( 20 genera and 55 species) on both DRBC and DG18 media. This may be due to t he higher moisture levels in peanuts (5.07-7.97%) compared with coconuts (1 .5-4.17%). More taxa and propagules were recovered on DG18 in both cases. T he dominant fungi from both substrates on both isolation media were Aspergi llus and Penicillium, with other fungi from only one substrate/medium. The aflatoxigenic species (A. flavus) dominated Kenyan samples more so than Uga ndan samples on both substrates. However only 71.5% and 87% of the peanut k ernels, on DRBC and DG18, respectively, were found to be infested with fung i. The aflatoxigenic species (A. flavus/parasiticus) were found in 75% of t he samples, however only 15.75% and 13% of the kernels analyzed were infest ed. The most frequently isolated species from peanuts were A. niger followe d by A. flavus and M. phaseolina. E. repens, E. amstelodami, E. rubrum and E. chevalieri dominated peanut seeds on DG18, and R. stolonifer, A. parasit icus, F. solani, L. theobromae and P. chrysogenum on DRBC. The mean count o f fungal propagules in coconut samples were approximately 0.7x 10(3) and 0. 8x 10(3) on DRBC and DG18, respectively, with a high proportion of those pr opagules recorded for the aflatoxigenic species (about 0.17x 10(3) and 0.25 x 10(3) colonies/g). The mycobiota of desiccated coconut was dominated by A . niger, A. flavus and P. chrysogenum. Also A. ochraceu, P. waksmanii, Paec ilomyces variotii, P. islandicum and R. mucilaginosa were more frequent on DRBC, while, species of Cladosporium, Chrysosporium and Eurotium were more frequent on DG18. Enzyme indices (or the activities) for each specific strain, when determine d after 5 and 8 days of incubation, proved to be similar. A recommendation is given. The proteolytic and lipolytic potentialities of the most commonly encountered species from both peanuts and coconuts were studied. The most interesting observation is that most of the positive isolates, in both comm odities had high enzymic activity compared to those reported earlier for is olates of the same species. Such capabilities suggest that these commoditie s are expected to deteriorate, since climatic conditions in tropical areas favour fungal proliferation. Emphasis on the proper harvesting, drying, han dling, transportation and/or storage; and also education of the populace, e specially those are dealing with these foods, should be taken into consider ation by the relevant authorities. The contaminated foods constitute a heal th hazard for human consumption.