Influence of Indigenous Saccharomyces cerevisiae Strains on Higher Alcohol Content in Malvazija Istarska Wines

Istria is one of the most remarkable wine growing regions in Croatia. The main white grape variety is Malvasia from Istria (Malvazija istarska). Commercial yeast inocula, generally Saccharomyces cerevisiae, are widely used as starters today, however it might be preferable to use selected indigenous strains, which may have optimum abilities and may be better adapted to ferment the must of each area. Production and final concentration of higher alcohols is one of the strains most important oenological properties. In this research we extensively studied three indigenous S. cerevisiae strains during three years, isolated from the Istra wine region. Content of higher alcohols (1-propanol, 1-hexanol, Isobutanol, 1-butanol, Isoamyl alcohol and 2-phenyl ethanol were analyzed using GC- SHS. Compared to the control strain all tested indigenous yeast strains produced significantly lower concentration of 1 propanol while only the strain RO 1203 produced higher concentration of Hexanol, Isobutanol and 2-phenyl ethanol in all investigated years. In the 2000 and 2001. wines produced with strain RO1172 had the lowest total higher alcohol amount while in the year 2002 there were no difference between tested strains. Sensory evaluation carried out by Buxbaum method pointed out good enological properties and positive influence on final wine quality of all three tested S. cerevisae indigenous strains.