Regulatory effects of sweet potato pericarp polyphenols on protein oxidation in commercial fresh milk

Abstract

This study explored the regulatory effects of sweet potato pericarp polyphenols on protein oxidation in commercially available fresh milk. Fresh milk samples from brands such as Yili, Mengniu, and Bright Dairy were collected and supplemented with sweet potato pericarp polyphenols. The samples were then stored at 4°C, and analyses were conducted to evaluate the antioxidant indices, protein oxidation products, microbial count, and texture parameters. The free radical scavenging capacities measured by 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt assays, as well as the decline in the total antioxidant capacity, were significantly lower in the treatment group compared with the control group. In addition, the treatment group showed lower carbonyl content, reduced oxidative loss of free sulfhydryl groups, inhibited excessive formation of disulfide bonds, a slower increase in thiobarbituric acid reactive substances values, suppressed protein hydrolysis, improved microbial safety, and enhanced textural stability. Therefore, sweet potato pericarp polyphenol can effectively inhibit protein oxidation in fresh milk, preserve protein structural stability, and enhance antioxidant and textural quality. These findings provide a theoretical basis for their potential application in fresh milk preservatives.