Role of Oak Wood Ellagitannins in the Oxidation Process of Red Wines During Aging

Abstract

The production of hydroperoxides and acetaldehyde and the kinetics of the oxidation process involving ellagitannins using model solutions containing ethanol (10% vol.), tartaric acid, iron, and copper were analyzed. Influence of oak phenolic compounds on wine aging in barrels under continuous-slow-oxidation conditions was also studied. Ellagitannins are revealed as impressive oxidation regulators, quickly absorbing the dissolved oxygen and facilitating the hydroperoxidation of wine constituents. This reaction induced tannin/anthocyanin condensation via acetaldehyde, favoring stabilization and deepening the crimson color; the limited oxidation of wine phenolic compounds prevented the development of brick-yellow color. In addition, the structure of the wine tannins was modified, reducing their astringency because of a higher polymerization level. Preliminary results on how ellagitannins affect the oxidation process of red wines are presented.