The study aims to document the microbial and pH changes occurring during the traditional fermentation of orange-fleshed sweet potato. Two traditional methods of fermenting orange-fleshed sweet potato slices (cold water fermentation (soaking) and hot water fermentation (parboiling) were used. A rapid drop in pH was measured over the first 3 days of the fermentation, after which the pH rose for both processes. The results showed that the optimum period for both the cold and hot fermentations of orange-fleshed sweet potato was 3 days. The mean bacterial counts (log10 cfu/g) were found to be consistently 1 log higher (P≤ 0.001) in the cold-water fermentation than in hot water fermentation. The bacteria found during the fermentation were Enterobacter cloacae and Leuconostoc mesenteroides in the cold-water fermentation whereas the same organisms as well as Bacillus cereus were isolated from the hot water fermentation process. The microbial content in amala produced front both fermentation methods was below detectable levels (< 2.0 log10 cfu/g). The results indicate there are no issues with the use of orange-fleshed sweet potato for human consumption in terms of microbial content, which could benefit the rural people.
Key words: Orange-fleshed sweet potato, traditional cold and hot fermentation, Enterobacter cloacae, Leuconostoc mesenteroides.
|
