Effect of fermentation, aging and thermal storage on total glycosides, phenol-free glycosides and volatile compounds of White Riesling (Vitis vinifera L.) wines

There is growing recognition of the significance of the products of glycosi de hydrolysis to varietal wine aroma. White Riesling wines were produced fr om four strains of Saccharomyces cerevisiae. Wines underwent conventional a ging or anaerobic thermal storage (20 days at 45 degrees C) either 2 or 40 months post-fermentation to quantify influences on total glycosides, phenol -free glycosides and selected volatiles. Glycoside and free volatile concen trations were estimated by analysis of glycosyl-glucose and gas chromatogra phy/mass spectrometry, respectively. Thermal storage of wines 2 months post -fermentation reduced the total glycosides by an average of 33% for all yea sts and increased the concentration of free benzyl alcohol while decreasing the concentration of free linalool and geraniol. Conventional aging for 40 months reduced the total and phenol-free glycosides equally among yeasts b y an average of 60%, with phenol-free glycosides averaging 80% of the total . Thermal storage of aged wines reduced the total glycoside concentration b y an additional 29%. The effect of thermal storage on selected volatile phe nols, higher alcohols, esters, acids, terpenes, carbonyl compounds, C-13 no risoprenoids and six-carbon alcohols was variable depending upon the compon ent.