Elucidation of key antioxidant components in red wine via challenge with a range of oxidants using an HPLC comparison to faux wine

Abstract

The purported health benefits of red wine owing to its antioxidant capacity attract persistent attention. The aims of this study were (1) to explore the contribution of individual phenolic constituents to the antioxidant capacity of red wine and (2) to investigate if non-phenolic components have oxidant or antioxidant effects. Red wine and a faux wine model systems of 11 constituent phenolic compounds were challenged with increasing concentrations of selected oxidants, namely hydrogen peroxide, redox-active transition metal ions and Fenton systems. Antioxidant activity was assessed through loss of phenolic components upon oxidant challenge measured using a reversed-phase high-performance liquid chromatography (HPLC) method. Elemental analysis of the red wine showed that the concentration of metal ions was in the range of 0.01–1.11 mM, whereas the concentration of antioxidant phenolics in the wine was in the range of 0.10–4.40 mM. As expected, addition of all five oxidant systems to both red wine and faux wine resulted in considerable loss of phenolics as quantified by HPLC. However, the pattern of phenolic loss was largely similar for both red wine and the faux wine across the five oxidant systems (frequently ca. 50–60% with the initial addition of oxidant), with only marginal effects on antioxidant activity after further additions of oxidants. The data revealed that the non-phenolic wine constituents had little influence over oxidative processes under the conditions studied, suggesting that the antioxidant properties observed in the tested red wine could be attributable to the phenolics.