Correlation of wine phenolic composition versus cyclic voltammetry response

Cyclic voltammetry has been used to quantify antioxidants at a carbon electrode in white wines diluted to 10% and red wines diluted to 0.25%. in a model wine solution (12% ethanol, 0.033 M tartaric acid adjusted to pH 3.6) The first peak near 400 mV (versus Ag/AgGl) was due to phenolic compounds with an orthodiphenol group or to gallic acid, while a small feature at 300 mV was seen in red wines containing higher levels of myricetins (triphenol on the flavonoid B-ring), and a peak or shoulder at 470 mV was ascribed to quercetin glycosides. The integral of the current to 500 mV was then used as a measure of the lower oxidation potential phenolics, reported as gallic acid equivalents, and Compared to traditional measures of total phenols in wines. A peak at 640 mV in red Wines was associated with malvidin anthocyanins and was smaller in an older red wine sample, while further oxidation current beyond 700 mV prominent in white wines was due to meta-diphenol or isolated phenol groups and other oxidizable compounds. Simulated voltammograms constructed from high-pressure liquid chromatography results for six monomeric phenolics were in good agreement with the experimental voltammograms for the white wines, while a higher proportion of the current for the red Wine samples was due to oligomeric phenolics.