OENOLOGICAL CHARACTERIZATION OF SOME YEAST STRAINS ISOLATED FROM THE IAȘI VINEYARD ROMANIA

This study investigated the oenological potential of indigenousSaccharomyces and non-Saccharomyces yeasts isolated from different stages of the natural must fermentation process. Screening of extracellular enzymatic activities was performed on agarized media in which the following substrates were added: arbutin, cellobiose, Tween 80, tributyrin, casein and citrus pectin, to highlight the activity of enzymes: ßglucosidase, esterase, lipase, protease and pectinase. Among the 30 Saccharomyces cerevisae strains tested, 37% showed very low β-glucosidase activity, 100% showed esterase activity, 40% lipase activity, 90% protease activity and 53% pectinase activity.The non-Saccharomyces strain tested showed β-glucosidase, esteraseand protease activity. Tolerance to ethanol was assessed in YPD medium with ethanol concentrations of 5, 10 and 15% (v/v) by yeast culture development index.At 15% ethanol, development of all tested strains were inhibited. In the case of SO2 tolerance, decrease in strains development was inversely correlated with the increase in potassium metabisulphite concentration, up to 200 mg/L. Only four Saccharomyces strains showed specific oenological characteristics and were selected to be tested in mixed and/or sequential cultures to obtain wines with improved sensory features.