Encapsulating vitamins C and E using food-grade soy protein isolate and pectin particles as carrier: Insights on the vitamin additive antioxidant effects

Functional factors show additive effects in the same nutraceutical food. In this study, a core-shell structure based on soy protein isolate (SPI) and pectin was constructed as a delivery system for vitamins C and E under neutral (pH 7.0) and acidic environment (pH 4.0). The SPI-vitamin-pectin complex formed at pH 4.0 showed larger particle size, higher turbidity, lower fluorescence intensity, and higher vitamin E encapsulation efficiency than those formed at pH 7.0. Also, the addition of vitamin C significantly enhanced the vitamin E encapsulation efficiency in the particles. Furthermore, the antioxidant properties of DPPH, ABTS, and hydroxyl radicals were increased by the addition of vitamin C, maximum values of 77%, 82%, and 65%, suggesting that vitamins C and E have additive antioxidant effects. These findings proposed a simple, structured protein-polysaccharide-based food-grade delivery system, which could serve as the basis for the design of products having multiple functional factors.