The Influence of SPI 7S and 11S on the Stability of Lonicera caerulea L. Anthocyanins and Interaction Mechanism with C3G

This study examined the effects of soy protein isolate (SPI) 7S and SPI 11S on the anthocyanin (AN) retention rate of Lonicera caerulea L. under different processing conditions and further analyzed the molecular interaction mechanisms between 7S/11S and cyanidin-3-O-glucoside (C3G). The results demonstrated that SPI increased the retention rate of anthocyanins to varying degrees while also enhancing the digestive stability. Multispectral results indicated that static quenching occurred between 7S/11S and C3G, and the polarity changes in the amino acid microenvironment varied with pH. Thermodynamic analysis indicated that hydrogen bonds dominated the interaction under both pH conditions, while a certain degree of hydrophobic interaction was additionally observed under neutral conditions. After binding with C3G, the proportion of β-sheet structures in SPI decreased and the proportion of other structures increased. Finally, molecular docking further simulated the binding between SPI and C3G and revealed the important roles of hydrophobic interactions and hydrogen bonding, which also promoted the combination of SPI and C3G to form a stable complex. This study provides a mechanistic reference for using proteins as effective carriers to protect anthocyanins, with implications for developing functional food components with enhanced stability.