Effect of Pomace-Contacting Method on the Concentration ofcis- andtrans-Resveratrol and Resveratrol Glucoside Isomers in Wine

Abstract

The effect of various pomace-contacting (maceration) methods on the concentrations of <i>cis</i>- and <i>trans</i>-resveratrol and resveratrol glucoside isomers were investigated in <i>Vitis vinifera</i> L. cv. Cabernet Sauvignon grape musts during alcoholic fermentation. Compared to a classical red wine vinification (control), carbonic maceration resulted in no detectable quantities of all four forms of resveratrol throughout fermentation and pressing. Prefermentation cold-soaking significantly increased (<i>p</i> &lt; 0.01) both free isomers of resveratrol in free-run, press, and mix wine despite no significant differences with the control in <i>trans</i>-resveratrol glucoside concentration and slightly less extraction of <i>cis</i>-resveratrol glucoside. Free resveratrol was absent in the must heated prior to fermentation, while the level of resveratrol glucosides significantly increased (<i>p</i> &lt; 0.001) relative to the control. In the final wines ready for bottling or aging, thermovinification proved most beneficial with respect to total resveratrol concentration, being 266% higher than that achieved in the control, while cold-soaking proved less beneficial, improving total resveratrol by 27%.