Effect of Different Indigenous Yeast β-Glucosidases on the Liberation of Bound Aroma Compounds

This study investigated beta-D-glucosidase activity in the indigenous wine yeast present on grape berries in Yantai in Shandong Province, China. Yeast population profiles from the Yantai production area in China were examined. Among the ten species identified by RFLP analysis of the 5.8S rRNA gene, four exhibited higher beta-glucosidase activity, namely, Hanseniaspora uvarum, Trichosporon asahii, Pichia fermentans and Saccharomyces cerevisiae. The beta-glucosidases from the four representative strains were chosen to hydrolyse the glycosidic precursors of Cabernet Sauvignon. After enzymatic hydrolysis, 31 compounds were identified and quantified, including terpenes, C13-norisoprenoid, C6 compounds, alcohols, aldehydes and volatile phenols. Results showed that different strains exhibited different hydrolytic abilities on the bound aroma precursors. The main variables included C6 compounds, terpenes and alcohols. The concentration of the 14 compounds showed significant differences between enzymatic treatments, with 11 treated using the beta-glucosidase of the F6 strain (T. asahii). These findings may have some applicative value for utilizing the strains or their beta- glucosidases, which are able to complement and optimize wine quality.