Evaluation in Quality Characteristics of Sweet Potato Powder by Different Preparation Processes

To screen for whole sweet potato powder (WSP) suitable for various industrial production processes, this study employed two representative sweet potato cultivars (Lingzi and Hong'anhong) as raw materials. It compared the variations in physicochemical properties, functional characteristics, sensory quality, and other related traits among four types of WSP produced by distinct processing methods: raw WSP, cooked WSP, freeze-dried WSP, and fermented raw WSP. The results showed that the pH of raw, cooked, and freeze-dried WSP ranged from 6.31 to 6.52, whereas fermentation decreased the pH of raw WSP to 4.42~5.90. Notably, single-strain fermentation using Lactiplantibacillus plantarum exhibited the strongest acid-producing capacity, with a total titratable acidity (TTA) value approximately three fold higher than that of unfermented raw WSP. Cooked WSP exhibited no endothermic peak, attributed to complete gelatinization. Among WSP samples of the same cultivar, cooked WSP had significantly higher water-holding capacity and water absorption-swelling capacity but poor freeze-thaw stability. Regarding oil-holding capacity, raw WSP was the lowest, whereas fermentation increased this capacity to more than twice its initial level. Furthermore, raw WSP fermented with single-strain L. plantarum had the highest soluble sugar content. Freeze-dried WSP performed best in sensory evaluation, with a total sensory score 7.56%~22.54% higher than those of the other types. For purple WSP, the anthocyanin content in freeze-dried purple WSP was approximately 5.32 times that in raw purple WSP. This study provides a valuable reference for the quality control, industrial-scale production, and application expansion of WSP.