Description of the beta-glucosidase activity of wine yeasts

beta-glucosidase activity of different Saccharomyces strains has been detected on the basis of its hydrolytic activity on para-nitrophenyl-beta-glucoside (pNPG) and terpene glycosides of Muscat wine. This enzymatic activity is induced by the presence of bound beta-glucose as the only carbon source in the medium and seems to be a characteristic of the yeast strain. beta-glucosidase is associated with the cell wall and is found in the insoluble fraction obtained from lysed yeast cells. Saccharomyces beta-glucosidase is quite glucose independent, so that its activity is reduced by about 40% in the presence of 200 g/l of glucose, but it is inhibited by about 50% with 5% ethanol in the medium; therefore, its technological use seems to be restricted to the first stages in the wine-making process. (C) 1997 Academic Press Limited.