In vitro protein digestibility and bioactive activities of yogurt from black soybean (Glycine max L.) milk

Black soybean raw material has high nutritional value and shows potential for producing plant-based yogurt alternatives. In this study, black soybean milk was fermented with a commercial yogurt starter to produce black soybean yogurt. The chemical composition, bioactive activities, amino acid profile, protein digestibility, release of free amino acids during in vitro digestion, and bioactive activities after in vitro digestion of black soybean yogurt and black soybean milk were compared. Fermentation led to a significant decrease in carbohydrate content (94.69 %db) while increasing protein (3.45 % db), fat (1.55 % db), and ash contents (0.30 % db). Black soybean yogurt exhibited higher α-amylase (1.26 mg acarbose/mL), α-glucosidase (31.33 mg acarbose/mL), and ACE inhibitory activity (97.10 %) than unfermented black soybean milk, with improved protein digestibility and higher release of free amino acids during in vitro digestion. The increased digestibility of black soybean yogurt contributed to higher bioactive activity in the digesta after the duodenal phase. Black soybean yogurt displays strong potential in the plant-based yogurt market due to its high nutritional value, complete amino acid profile, easy digestibility, and potent bioactive properties.