Analysis Of So_2-resistant Polymeric Pigments In Red Wines By High-performance Liquid Chromatography

摘要

A simple modification, the addition of SO_2 to the mobile phases, to an existing HPLC method for the analysis of unbleached polymeric pigments in red wines using a silica-based polymeric column is described for the first time. The samples included wines made from Pinot noir, Merlot, Cabernet Sauvignon, Cabernet franc, Sangiovese, Cagnulari, and Cannonau grapes, mostly from the 2001 season, which covered a range of wine color from 0.1 to 10 absorbance units at 520 nm. Results were compared to the level of SO_2-resistant polymeric pigments as measured by an existing spectrophotometric assay (R~2 = 0.992). In these wines, the ratio of the color of the bleached polymeric pigments to that of the unbleached polymers averaged 0.19 with a coefficient of variation of 34%. The SO_2-resistant polymeric pigments estimated by this HPLC method are also in good agreement with those quantified by the protein precipitation spectrophotometric method of Harbertson and Adams (R~2 = 0.950).