ROLE OF OAK WOOD ELLAGITANNINS IN THE OXIDATION PROCESS OF RED WINES DURING AGING

The production of hydroperoxides and acetaldehyde and the kinetics of the oxidation process involving ellagitannins using model solutions co ntaining ethanol (10% vol.), tartaric acid, iron, and copper were anal yzed. Influence of oak phenolic compounds on wine aging in barrels und er continuous-slow-oxidation conditions was also studied. Ellagitannin s are revealed as impressive oxidation regulators, quickly absorbing t he dissolved oxygen and facilitating the hydroperoxidation of wine con stituents. This reaction induced tannin/anthocyanin condensation via a cetaldehyde, favoring stabilization and deepening the crimson color; t he limited oxidation of wine phenolic compounds prevented the developm ent of brick-yellow color. In addition, the structure of the wine tann ins was modified, reducing their astringency because of a higher polym erization level. Preliminary results on how ellagitannins affect the o xidation process of red wines are presented.