Enhancement of Antioxidant Capacity of Purple Sweet Potato Anthocyanins by Wheat Oligopeptides under Acidic Conditions

Abstract

Under the acidic conditions (pH 4.0), the addition of wheat oligopeptides (WOPs) (25~100 g/L) decreased the thermal stability of purple sweet potato anthocyanins (PSPAs), but enhanced its antioxidant capacity, which increased with the rise of the additive amount. When the addition was 100 g/L, the DPPH, ABTS free radical scavenging capacity and FRAP total antioxidant capacity of PSPAs solution after in vitro simulated digestion were increased by 1.5 times, 34 times and 34%, respectively. After storage at 37 ℃ and 45 ℃ for 7 d, the antioxidant capacity did not change significantly, and it had stronger biological activity and higher stability than those of PSPAs. UV and fluorescence spectra showed that PSPAs can affected the redshift of absorption peak and fluorescence quenching at specific wavelength of WOPs at experimental concentration, which proved the interaction between WOPs and PSPAs. It can be seen from the above that WOPs have the potential to be applied in the development of acidic PSPAs beverages.

Keywords

• purple sweet potato anthocyanins
• wheat oligopeptides
• antioxidative activity
• stability
• interaction