Analysis of the nutritional properties and flavor profile of sweetpotato residue fermented with Rhizopus oligosporus

Sweetpotato residue, a by-product generated after starch extraction in the food industry, has not been effectively utilized. In this study, fermentation with Rhizopus oligosporus RT-3 was carried out to improve the nutritional properties and flavor profile of sweetpotato residue. The contents of soluble dietary fiber, protein, phenolics and flavonoids and the antioxidant activities of sweetpotato residue significantly increased during fermentation. The analysis of headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and sensory evaluation indicated that fermentation enhanced the aroma of sweetpotato residue due to the increased levels of alcohols, esters, ketones, and alkenes. Metabolite analysis further revealed that fermentation remarkably improved the nutritional composition of the sweetpotato residue. The potential metabolic pathways triggered during fermentation demonstrated that the improved nutritional composition of sweetpotato residue was attributed to the biochemical reactions driven by microbial enzymes.