Redox Behavior of Anthocyanins Present in Vitis vinifera L.

Voltammetric techniques were employed to study the electrochemical behavior of several anthocyanins. The redox behavior of anthocyanins with the same basic structure, the influence of glycosylation on the redox behavior of anthocyanins derived from different anthocyanidins, and the influence of methoxylation were investigated. The anthocyanins used in this study were malvidin‐3‐O‐glucoside chloride, malvidin‐3,5‐di‐O‐glucoside chloride, cyanidin‐3‐O‐glucoside chloride, cyanidin‐3,5‐di‐O‐glucoside chloride, peonidin‐3‐O‐glucoside chloride, delphinidin‐3‐O‐glucoside chloride and the anthocyanidin petunidin chloride, all of them present in Vitis vinifera L. All hydroxyl groups of the anthocyanins can be electrochemically oxidized and the anthocyanins studied revealed a complex and pH dependent oxidation process, with the occurrence of adsorption and of oxidation products blocking the electrode surface.