Characterization of microorganisms associated with sweet potato spoilage

Sweet potatoes are staple food crops, especially in developing countries. However, spoilage of sweet potatoes due to microbial contamination is a major problem, causing significant economic losses. The most common microorganisms associated with spoilage of sweet potatoes are Bacteria and Fungi. This study was aimed at characterization of microorganisms associated with sweet potato spoilage in Awka, Anambra State. Six samples of decaying sweet potatoes were obtained at different locations at Eke Awka Market in Awka. Nigeria. The samples were serially diluted and inoculated on nutrient agar and Sabourauds Dextrose Agar to assess for bacterial and fungal growths respectively. Discrete colonies were obtained and identified using appropriate microbiological and biochemical methods. From the result, the total bacterial count ranged from 1.02 x 10* to 5.40 x 10* while the mean fungal count ranged from 1.36 x 106 to 1.71 x 106. The result showed that all the samples had both bacterial and fungal isolates which can be associated with the spoilage mechanism. The fungal population is much more than the bacterial population and this shows that bacteria are the predominant microorganisms responsible for the spoilage of sweet potato during storage. The bacterial isolates include Staphylococcus spp and Streptococcus spp while the fungal isolates are Candida albicans and Saccharomyces cerevisae. Since sweet potatoes have been described as having thin, delicate skin that is easily damaged by cuts and abrasion during harvesting, transportation or distribution. concerted efforts should therefore be directed towards minimizing or reducing this so as to avoid physical damage to the tuber and thereby reducing or preventing microbial attack. In order to mitigate the rate at which microorganisms cause deterioration of sweet potato, several control techniques such proper washing of the harvested tuber, cleaning of transit containers, proper handling of the tuber in order to avoid injuries, good hygienic practices by the handlers, provision of good and healthy storage facilities must be put in place.