Inhibitory effects of ultrasound combined with ascorbic acid or glutathione on enzymatic darkening of whole-wheat raw noodles

Abstract

The effects of ultrasound combined with ascorbic acid or glutathione on the inactivation of polyphenol oxidase (PPO) in whole-wheat flour (WWF) and the prevention of enzymatic darkening of whole-wheat noodles (WWN) were studied. The residual PPO activity, free phenolics content, thermal properties, representative mineral elements, and B vitamins in WWF as well as the discoloration over 24 h, and textural characteristics of WWN after treatments were determined. The combination of ultrasound with ascorbic acid was proven to be the most effective treatment that reduced PPO activity in WWF and effectively prevented the enzymatic darkening of WWN. Moreover, the thermal properties, mineral element, and B vitamins in WWF, and the textural characteristics of WWN were little affected by ultrasound treatment and the two antioxidants. The results suggested that the combined treatments with ultrasound and antioxidants have exhibited significant effectiveness in maintaining the color stability and improving the overall quality of WWN.