Enzymatic Characterization of Purified β -Glucosidase from Non- Saccharomyces Yeasts and Application on Chardonnay Aging

The application of -glucosidase from non- yeasts to improve wine aroma has been widely explored. However, few enzymes are active under the severe conditions of wine aging (high ethanol concentration, low temperature, and low pH). Therefore, the application of -glucosidase in wine aging needs further research. In this study, the -glucosidases Mg-βgl and Hu-βgl extracted from NM218 and BF345 were purified and used in young Chardonnay wines aged for 50 days. The enzyme activity of the two enzymes was measured. The effects of the two enzymes and a commercial -glucosidase (An-βgl) on the volatile composition and sensory quality of the wine were also determined. The results showed that Mg-βgl and Hu-βgl had high specific activity of 1.95 U/mg and 2.11 U/mg, respectively, maintaining the activity of 70-80% at 20 °C, pH of 3.0-4.0, and 15% ethanol, corresponding to wine aging conditions. Analysis of volatiles with GC-MS showed a 65-70% increase in total terpenoids and new detection of C -norisoprenoids when the wines were treated with the three -glucosidases. In addition, wines treated with Mg-βgl and Hu-βgl had more hexanol, phenylethanol, ethyl octanoate, ethyl heptanoate, and ethyl caprate than wines treated without and with An-βgl. In sensory analysis, the judges showed a greater preference for Hu-βgl-treated wines, to which they attributed pleasant sweet, floral, honey, pomelo, and banana aromas. The results of this study not only offer a way to improve flavor complexity in wine but also provide a reference for the use of other edible sources of -glucosidase in wine aging.