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| - Redox Chemistry of Red Wine. Quantification by an OscillatingReaction of the Overall Antioxidant Power as a Function of theTemperature
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| - The redox and acid−base reactivity of red wines was studied from both the analytical and kineticstandpoint. Four homemade wines, made from Italian red grape varieties of two different vintages,were tested to study the effect of temperature (25 and 37 °C) on the overall antioxidant power, throughthe Briggs−Rauscher oscillating reaction. The reaction was monitored by potentiometry (platinumelectrode) and by direct chronometric detection. A reference scale based on the response of gallicacid was also employed, so as to achieve a quantitative evaluation: the novel Briggs−Rauscherantioxidant index (BRAI) was developed to express the overall antioxidant power quantitatively versusthe chosen standard molecule. Overall antioxidant power was found to be related to total polyphenolcontent measured using the Folin−Ciocalteu method: the older wines had a lower antioxidant ability.Total acidity was also estimated indirectly by means of coupled pH-metric/photometric titrations andvisible spectrophotometric measurements; it revealed an overlap between acid−base and redoxchemistry of red wine. Keywords: Antioxidant power measurement; redox chemistry; red wine; polyphenols; gallic acid; color-acidity relation; free radicals
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