Isolation and Determination of Polymeric Polyphenols in Wines Using Sephadex LH-20

Abstract

Chromatography on Sephadex LH-20 separated non-polymeric and polymeric phenols in wines. Concentrations of polymeric phenols in white wines made with five-day pomace contact were directly related to polymeric phenol concentrations in skin tissues. Although polymeric phenol concentrations in solid tissues of white and red grape varieties were found to be similar, white wines made with the same pomace contact time as red wines were found to contain much lower concentrations of polymeric phenols. This strongly suggests that anthocyanins greatly enhance transfer or retention of polymeric phenols in wines. Mature pigment polymers in aged red wines were not retained by Sephadex LH-20, showing that these polymers have different size or hydrogen-bonding properties than the condensed tannin polymers found in solid grape tissues and young wines. By combining results obtained by dialysis and the Sephadex procedure, an estimate can be made of the "residual tannin" and "mature polymer" concentrations in aged red wines.