Effects of black soybean peel anthocyanins on the structural and functional properties of wheat gluten

Wheat gluten (WG) is a crucial cereal protein commonly utilized in the food, biological and pharmaceutical industries. However, WG is poorly soluble in water, resulting in poor functional properties, which restrict its application in the food industry. As a result, there is an urgent need for improving the properties of WG.

This study was conducted to examine the functional properties of WG after binding with black soybean peel anthocyanin extract (BAE). Results showed that BAE enhanced the solubility, water-holding and antioxidant capacity, foaming properties and emulsifying activity of WG, while decreasing the emulsion stability. The degree of hydrolysis of WG and retention rate of BAE became higher in the digested WG-BAE complex than in the control groups. Additionally, an analysis was conducted on the mechanism of interaction between cyanidin-3-O-glucoside (C3G) and WG/gliadin (Gli)/glutenin (Glu). The secondary structure of WG/Gli/Glu was altered after adding C3G. C3G had high affinity for WG/Gli/Glu since their binding constants were greater than 10⁴ L mol^-1. The primary binding forces between C3G and WG/Gli were hydrophobic interactions, whereas the main interaction forces between C3G and Glu were hydrogen bonding and van der Waals forces. Moreover, C3G increased the thermal stability and changed the network structure of WG/Gli/Glu.

This study revealed that BAE effectively enhanced a range of functional properties of WG. The interaction between WG and BAE also improved the bioavailability and nutritional value of them. Furthermore, the interaction mode between BAE and WG was investigated. These findings lay a foundation for utilizing gluten-anthocyanins in the food sector. © 2024 Society of Chemical Industry.