Isolation and Investigation of Potential Non-Saccharomyces Yeasts to Improve the Volatile Terpene Compounds in Korean Muscat Bailey A Wine

The Muscat Bailey A (MBA) grape, one of the most prominent grape cultivars in Korea, contains considerable amounts of monoterpene alcohols that have very low odor thresholds and significantly affect the perception of wine aroma. To develop a potential wine starter for Korean MBA wine, nine types of non-Saccharomyces yeasts were isolated from various Korean food materials, including nuruk, Semillon grapes, persimmons, and Muscat Bailey A grapes, and their physiological, biochemical, and enzymatic properties were investigated and compared to the conventional wine fermentation strain, Saccharomyces cerevisiae W-3. Through API ZYM analysis, Wickerhamomyces anomalus JK04, Hanseniaspora vineae S7, Hanseniaspora uvarum S8, Candida railenensis S18, and Metschnikowia pulcherrima S36 were revealed to have beta-glucosidase activity. Their activities were quantified by culturing in growth medium composed of different carbon sources: 2% glucose, 1% glucose + 1% cellobiose, and 2% cellobiose. W. anomalus JK04 and M. pulcherrima S36 showed the highest beta-glucosidase activities in all growth media; thus, they were selected and utilized for MBA wine fermentation. MBA wines co-fermented with non-Saccharomyces yeasts (W. anomalus JK04 or M. pulcherrima S36) and S. cerevisiae W-3 showed significantly increased levels of linalool, citronellol, and geraniol compared to MBA wine fermented with S. cerevisiae W-3 (control). In a sensory evaluation, the flavor, taste, and overall preference scores of the co-fermented wines were higher than those for the control wine, suggesting that W. anomalus JK04 and M. pulcherrima S36 are favorable wine starters for improving Korean MBA wine quality.