Effects of Various Vinification Techniques on the Concentration ofcis- andtrans-Resveratrol and Resveratrol Glucoside Isomers in Wine

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The influence of two different yeast strains and the effect of malolactic fermentation on the content of cis- and trans-resveratrol and resveratrol glucoside isomers in wine was studied, as well as the effect of gelatin and PVPP fining. The analyses of trans-, cis-resveratrol and resveratrol glucoside isomers were carried out by RP- HPLC separation. The yeasts with higher β-glucosidase activity significantly increased (p < 0.001) the concentrations of cis- and trans resveratrol and decreased the concentration of tran/-resveratrol glucoside, while malolactic fermentation had less effect on their concentrations (p < 0.05). Treatment of wine with gelatin had no effect, neither on free nor on glucosidic forms. The aglycone forms showed significant binding to PVPP (up to 90%), but glycosides showed less binding (up to 10%).