A cyclic voltammetry method suitable for characterizing antioxidant properties of wine and wine phenolics

Phenolic antioxidants are ranked by reducing strength and characterized for reversibility using cyclic voltammetry at a glassy carbon electrode. Pheno lics with an ortho-diphenol group show a first oxidation peak close to 400 mV (vs. Ag/AgCl) in a model wine solution (12% ethanol, 0.033 M tartaric ac id, adjusted to pH 3.6), with a linear concentration dependence below 0.01 mM. Dilution of white wines 10x, and red wines 400x, gave first oxidation p eak currents in the 1.5 to 2.2 muA range and 1.9 to 3.4 muC of charge passe d by 500 mV, producing values for the concentrations of phenolic antioxidan ts with low oxidation potentials in the wines. Further peaks in the cyclic voltammograms of the diluted wines correspond to classes of phenolics with higher oxidation potentials, providing a qualitative assessment of wine phe nolics based on reducing strength.