EFFECT OF FERMENTATION, STORAGE SUR LIE OR POSTFERMENTATION THERMAL-PROCESSING ON WHITE RIESLING (VITIS-VINIFERA L.) GLYCOCONJUGATES

Four strains of Saccharomyces cerevisiae were evaluated for their infl uence on White Riesling glycoconjugates. Fermentation resulted in a de crease in bound glycosides, as estimated by the analysis of glycosyl g lucose. The greatest reduction occurred with the Fermiblanc strain, al though the maximum difference among yeasts was only 7%. The concentrat ion of bound monoterpene alcohols, oxides, and aromatic alcohols was d iminished due to fermentation, although generally similar among yeasts . Following fermentation, the concentration of free terpenes and aroma tic alcohols differed slightly among yeasts, but differences were belo w the sensory thresholds reported for each compound. Post-fermentation thermal processing reduced the glycoconjugates by an average of 33% f or all treatments, with the greatest reduction occurring with the VL1 strain. Storing wines for 45 days sur lie lessened the glycoside conte nt uniformly among treatments by 52%.