Abstract: In this study, sweet potato slurry that can be used for starch production was fermented using Lactobacillus plantarum (Lp), Lactobacillus bulgaricus (Lb), Streptococcus thermophilus (St), Pediococcus pentosus (Pp), Lactobacillus casei (Lc) and commercial Lp (SZ), separately, and the effects of different lactic acid bacteria (LAB) starter cultures on the nutritional and functional components (protein, ash, soluble dietary fiber, insoluble dietary fiber, total dietary fiber, total acid, total sugar, lactic acid, short chain fatty acid, total polyphenol, and free amino acid) and sensory characteristics (evaluated by electronic nose, electronic tongue, gas chromatography-mass spectrometry (GC-MS), and sensory evaluation) of sweet potato slurry were compared. The results showed that after fermentation, the contents of protein, sugar, soluble dietary fiber, insoluble dietary fiber and total dietary fiber decreased significantly. All starter cultures showed excellent fermentation performance. After fermentation, the pH of the slurry decreased from 6.62 to 3.67–3.88, the total acid content increased from 0.29 to 2.69–3.67 g/100 mL, and the contents of lactic acid and short chain fatty acids increased significantly. Lb and Lc fermentation significantly increased the content of total polyphenols in the slurry by 18.44% and 17.78%, respectively. Additionally, 16 free amino acids were detected in the fermented slurry, and the content of essential free amino acids increased significantly compared to that in the unfermented slurry. The GC-MS profile showed that lactic acid bacteria fermentation remarkably increased the number and amount of flavor substances in the slurry and improved its flavor and mouthfeel. The slurry fermented by Pp, St and SZ exhibited better overall sensory acceptability than that fermented by the other starter cultures. In conclusion, these findings can provide theoretical support for the research and development of LAB-fermented beverage from sweet potato starch slurry.

Key words: sweet potato starch slurry; Lactobacillus; nutritional and functional components; sensory characteristics