Effect of Fermentation, Aging, and Agingsur Lieon Total and Phenol-Free Riesling (Vitis viniferaL.) Glycosides

Grape-derived glycosides are, in part, important aroma precursors. Quantification may offer a means of determining the impact of processing methods on potential wine quality. Several studies were conducted to evaluate the influence of four strains ofSaccharomyces cerevisiaeon total and phenol-free Riesling glycosides during fermentation and following aging for 40 months or 40 monthssur lie(with yeast). Fermentation decreased the total and phenol-free glycoside concentrations, as estimated by the analysis of glycosyl-glucose, although the maximum difference among yeasts was only 7.6%. Fermentation had little effect on the percentage of phenol-free to total glycosides which averaged 61.5%. Aging 40 months or 40 monthssur liereduced the total glycoside concentrations by an average of 59.6 and 73.4%, respectively, resulting in no differences among yeast strains. Phenolic-free glycosides averaged 80% of the total in the aged wines.