The role of non-Saccharomyces species in releasing glycosidic bound fraction of grape aroma components - a preliminary study

AIMS: The purpose of the study was to evaluate the effect of beta-glycosidase activity in wine yeasts in releasing terpene glycosides from grape juice. METHODS AND RESULTS: Glycosidase activity was screened in 160 yeasts by testing their ability to hydrolyse arbutine on agar plates. Only non-Saccharomyces species exhibited beta-glycosidase activity. Enzyme activity, based on hydrolytic activity on p-nitrophenyl-beta-glycoside, was mainly located in the whole cell fraction, with smaller amounts in permeabilized cells being released into the growth medium. The hydrolysis of glycosides was determined by HRGC-MS, confirming the role of yeast in the liberation of monoterpenols, especially linalool and geraniol. CONCLUSION: The results indicate the potential of microbial beta-glycosidases for releasing flavour compounds from glycosidically-bound, non-volatile precursors, with significant implications for wines made from less aromatic grapes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study confirms the role of non-Saccharomyces species in enhancing wine aroma and flavour, suggesting that the future lies with controlled use of mixed cultures in winemaking.