Electrochemical Basis for Re-evaluating Antioxidant Effect of Redox Substances in Foodstuffs

Abstract

Differences in the mechanisms of in vitro antioxidant actions provide difficulties in evaluating antioxidant power and in choosing correct antioxidants for certain foodstuffs. In view of the reducing, antiradical, and pro-oxidant abilities of certain redox substances, an electrochemical approach was applied in this Review for re-evaluating antioxidant properties. The redox basis was discussed to provide a holistic view with respect to polyphenols acting both as reducing and antiradical agents. Quantitative (quantity of reduced forms) and qualitative (standard redox potential) constituents of reducing power were analyzed. Antioxidant vs pro-oxidant effects of polyphenols in foodstuffs were shown to rely upon the thermodynamic viability of redox reactions. It was demonstrated that the intermediate products of redox reactions of polyphenols (semiquinones) may act as antiradical agents. The article is based on previous works and outlines the further research for a practical application of electrical current in determining and improving the antioxidant capacity of foodstuffs.

Characterization of 20 Oenological Tannins from Different Botanical Origins for Formulation of Blends with Redox Potential Tuning Ability in Model Wine Solution

“…The antioxidant property of the oenotannin solutions was measured by the DDPH assay, since it was able to show both mechanisms of hydrogen atom transfer (HAT) and single-electron transfer (SET) [25]. All the solutions showed a general high antioxidant power value (Table 2), ranging from 90.10% for the CIT tannin extract from citrus wood to 95.96% for the TAR tannin extract from tara.…”

“…), but the characteristic of an antioxidant agent connected with its redox potential cannot be evaluated by the above methods. Then, a suitable characterization of the antioxidant properties should be also carried out using electrochemical methods, which are able to measure the oxidation or reduction state of a medium [25]. The common electrochemical methods in enology consist (i) in the zero-current potential of a platinum electrode [26,27] or (ii) in the cyclic voltammetry based on measurement of the electric current intensity due to increase/decrease of potential at 100 mV/s using glassy carbon electrodes [28,29].…”