Components and Antioxidant Activity during the Fermentation Process of Kidney Bean Jiaosu

Kidney bean Jiaosu was prepared from purple kidney bean, pH, total acid, reducing sugar, soluble solid, total phenol and flavone were used as evaluation indexes of active constituents, and the variation rule of each component content were explored, the correlation between each component in the fermentation process and antioxidant activity parameters (reduction power, ABTS free radical scavenging rate) was analyzed. The results showed that during the fermentation process of kidney bean Jiaosu, pH decreased continuously and then tended to be flat, the change law of total acid was opposite. The content of reducing sugar increased from the initial stage of fermentation to 11.2 mg/mL, subsequently, it kept decreasing and reached the minimum value of 3.55 mg/mL after 48 h fermentation. The soluble solid content decreased from 17.07% to 6.01%. The total phenol content showed an upward trend on the whole, decreased only at 32 h of fermentation, and reached a maximum of 367.92 mg/mL at the end of fermentation. The flavones content showed a trend of continuous increase and tended to be stable after fermentation for 48 h, reaching 92.24 g/mL. The antioxidant capacity of kidney bean Jiaosu (reducing power, ABTS free radical scavenging rate) showed a continuous growth trend and reached a stable state in the late fermentation period, reaching the maximum value (0.88, 88.12%) at 56 h of fermentation. The correlation between functional components and antioxidant capacity parameters showed that the total phenols and the flavones were significantly positively correlated with reducing power and ABTS⁺ free radical scavenging capacity(P<0.05).