Identification of new oxidation markers of grape-condensed tannins by UPLC-MS analysis after chemical depolymerization

Model solutions of oxidized monomer/dimer mixtures of flavan-3-ol (EC/B2, EGC/B2, ECG/B2, EGCG/B2) were studied after chemical depolymerization by UPLC-MS. New oxidation markers of condensed tannins were identified. This analytical method was applied to a wine sample and most of these oxidized markers were detected. This method will permit following the oxidation state of tannins during the winemaking process and storage in order to improve the quality of the products. (C) 2015 Elsevier Ltd. All rights reserved.