Development of Functional Msalais Wines Rich in Amadori Compounds by Yeast Fermentation

Msalais is a type of wine made by a series of processes such as boiling and fermentation from Hotan red grape juice. The Maillard reaction occurs during the boiling of the grape juice. The Amadori compound is a product of the early stage of the Maillard reaction, which has physiological activities such as antioxidation, anti-hypertension, and anti-hyperglycemia. The purpose of this study was to develop Msalais rich in Amadori compounds by utilizing the fermentative capabilities of different yeasts. The optimal fermentation process was obtained by response surface optimization, with the key parameters as follows: <i>Saccharomyces cerevisiae</i> Y4 and <i>Wickerhamomyces anomalus</i> Y2 (as the fermenting yeasts), fermentation temperature of 28 °C, fermentation time of 14 days, yeast inoculation amount of 2% (<i>V</i>/<i>V</i>), and ratio of <i>Saccharomyces cerevisiae</i> to non-<i>Saccharomyces cerevisiae</i> of 2:1. At the same time, HPLC-ELSD was used to detect Amadori compounds in the product of this optimal fermentation process. The contents of Fru-Pro and Fru-Asp in the optimal fermentation process were 0.2867 ± 0.0115 g/L and 0.0203 ± 0.0014 g/L, respectively, which were 0.0702 g/L and 0.026 g/L higher than those of commercially available commercial Msalais (0.2165 ± 0.0022 g/L and 0.0177 ± 0.0008 g/L, respectively). With the increase in the content of Amadori compounds, the antioxidant activity was significantly improved. The DPPH free radical scavenging ability was 116.37 ± 1.79 μmol Trolox/sample, which was 53.01 μmol Trolox/L sample higher than that of commercial Msalais. The ABTS free radical scavenging ability was 142.51 ± 1.98 μmol Trolox/L sample, which was 68.23 μmol Trolox/L sample higher than that of commercial Msalais. The total oxygen free radical absorption capacity was 132.74 ± 6.36 μmol Trolox/L sample, which was 60.12 μmol Trolox/L higher than that of the commercial Msalais. Compared with traditional Msalais produced by natural fermentation, the quality of Msalais fermented by specific yeasts has been significantly improved. These results provide a reliable basis for the fermentation of Msalais by specific yeasts and its quality optimization.