The prevention of pathologies associated with oxidative stress has been related to red wine consumption and antioxidant phenolic compounds have been suggested as being responsible of this effect. To study factors influencing the antioxidant capacity (AC) and phenolic composition of red wines, different viticulture, vinification and maturation processes of the red wine variety Tannat were studied. AC correlated with total polyphenol content at 1, 6 and 12 months post-fermentation times. In all wines studied, AC increased with aging although most of the phenolic families remained constant, suggesting the relevance of qualitative changes of these compounds for AC. Changes in field treatments such as etephon application, the timing of the application and variations in wine making techniques such as the use of S. cerevisiae var. ellipsoideus or a "color extractor" pectinolytic enzyme were the most effective in increasing AC. (c) 2004 Published by Elsevier Ltd.