Effect of Winemaking on Phenolic Compounds and Antioxidant Activities of Msalais Wine

Msalais wine (MW) is a popular traditional wine with the cultural characteristics of a specific Chinese ethnic group. In this study, phenolic profiles and antioxidant characteristics were identified using chromatographic analysis. A total of thirty-eight compounds, including eight furans, eleven phenolic acids, fourteen flavonoids, and five others, were identified via LC-MS/QTOF. It was found that catechin is the most abundant phenolic compound in MW, followed by epicatechin, gallic acid, caffeic acid, rutin, and p-coumaric acid. Winemaking had a significant influence on the levels of phenols and antioxidant activity. Condensed juice (CJ) displayed the highest phenol and antioxidant activity levels, while the levels were significantly decreased during the fermentation process and gradually stabilized thereafter during the aging process. A correlation analysis between the polyphenols in Msalais and their antioxidant capacity was performed to determine which molecules contributed more to the antioxidant capacity in a complex mixture of polyphenols. All of the phenolic compounds, except ferulic acid, showed good correlation with DPPH, ABTS, and CUPRAC. Among them, resveratrol had the strongest antioxidant capacity, although its concentration was very low. Catechin also had a strong antioxidant capacity, which was positively correlated with its concentration. This indicates that the antioxidant activity of Msalais is related to the number, type, and structure of polyphenols.