Effect of Principal Polyphenolic Components in Relation to Antioxidant Characteristics of Aged Red Wines

TLDR

Aged red wines have a different polyphenolic composition than young wines due to polymerization, oxidation, hydrolysis, and other transformations of native grape phenolics during aging. The study aimed to examine the relationship between polyphenolic content and antioxidant activity in Greek single‑variety aged red wines. Total phenol, flavanol, and anthocyanin contents were measured by spectrophotometry, and HPLC was used to identify individual polyphenols responsible for antioxidant effects. Total flavanols were the main contributors to hydroxyl‑radical scavenging and, to a lesser extent, to antiradical and reducing activities, while antioxidant properties were largely due to synergistic interactions among phenolics rather than individual compounds.

Abstract

Aged red wines possess significantly different polyphenolic composition compared with young ones, mainly due not only to formation of polymeric compounds but also because of oxidation, hydrolysis, and other transformations that may occur in native grape phenolics during aging. Representative Greek, single-variety, aged red wines were examined for total phenol, total flavanol, and total anthocyanin content using spectrophotometry, and attempts were made to establish correlations with the antiradical, reducing, and hydroxyl free radical scavenging activity. In addition, HPLC analyses were carried out, to ascertain whether individual polyphenols are actually responsible for the antioxidant effects of aged red wines. It was found that total flavanols are the class of polyphenols that account for hydroxyl free radical scavenging efficacy and to a lesser extent for antiradical and reducing ability, whereas there was a less significant link between the antioxidant properties and the total phenolics and only a weak relationship to total anthocyanin content. The correlation of the antioxidant properties with the principal polyphenols showed that individual compounds are weakly associated with all the antioxidant parameters, suggesting that the expression of antioxidant activity in aged red wines is rather a consequence of synergism between various phenolics, and it is not simply attributed to specific constituents.