Microbiological and physicochemical properties of fermented and unfermented sweet potato flour

Abstract

This research accesses the suitability of using processed flours from fermented and unfermented yellow-fleshed sweet-potato as alternative flour based on their physiochemical and microbiological properties. Raw yellow sweet potato tubers were obtained from a local Nigerian market and processed into fermented and unfermented sweet potato flours. Their microbiological and physiochemical (proximate and functional) properties were analyzed using standard methods. The microbiological results identified six bacterial genera; (Bacillus, Klebsiella, Micrococcus, Staphylococcus, Lactococcus, and Enterobacter) and five fungal genera (Aspergillus, Penicillium, Mucor, Candida, and Saccharomyces). Bacillus and Aspergillus spp. were the most dominant bacterial and fungal genera respectively. The physiochemical result reveals that fermenting sweet potato flour resulted in improved protein, moisture content, and water and oil adsorption capacities compared to the unfermented flour. The pH also decreased from 8.8 to 5.0 after 72 h of fermentation. Most of the microorganisms isolated are associated with plants, water, environment, and fermentation, they are generally recognized as safe (GRAS) organisms and their potentials can be further exploited in the food industry. These findings highlights the potentials of incorporating fermentation techniques in enhancing the nutritional and techno-functional attributes of sweet potato flour as a healthy alternative gluten-free flour-based staple diet.