ANTIOXIDANT ACTIVITY EVOLUTION DURING PORTUGUESE RED WINE VINIFICATION AND THEIR RELATION WITH THE PROANTHOCYANIDIN AND ANTHOCYANIN COMPOSITION

Abstract

The aim of this work was to evaluate the evolution of antioxidant activity and its relation to phenolic composition during the vinification of two Portuguese red grape varieties (Tinta Roriz and Touriga Nacional). Two analytical methods were used to analyze antioxidant activity: 2.2-diphenyl-1-pirylhydrazyl (DPPH) radical scavenging assay and 2,2′-azinobis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical cation scavenging assay. Total polyphenols and tannins, different proanthocyanidins fractions according to their degree of polymerization and individual anthocyanins were evaluated by high-performance liquid chromatography as well. During the maceration time, an increased antioxidant capacity was measured followed by a slight decrease in the values over the last two maceration days. A similar evolution was quantified for total polyphenols, total tannins and for the different proanthocyanidin fractions. An increase of the values was verified for the individual anthocyanins quantified but with several slight oscillations during the maceration process. High linear positive correlations among the phenolic composition, different proanthocyanidin fractions (especially for monomeric fraction) and the antioxidant activity evolution during the maceration process were quantified. For the individual anthocyanins, a high disparity of the correlation values was found, and it was not possible to obtain a clear standard. PRACTICAL APPLICATIONS Knowledge of antioxidant capacity evolution and its relation to phenolic extraction (especially proanthocyanidins and anthocyanins) during winemaking is important for red wine production, optimization and consequently for red wine quality. Additionally, the information yielded in our study will be useful to obtain wines with maximum antioxidant capacity, especially when two important Portuguese grape varieties are used, commonly used in several Portuguese wine regions (but also in other wine-producing countries such as Brazil and Australia, where these two grape varieties, especially Touriga Nacional, are used). Thus, this study is particularly important when the “antioxidant power” of foods, in this case in red wine, is an expression of its capacity both to defend the human organism from the action of free radicals and to prevent degenerative disorders deriving from persistent oxidative stress.