Polyphenol content and antioxidant activity of merlot and shiraz wines

The total polyphenol content, antocyanins, proantoacyanidins, and some phenols were determined in fifteen red wine samples of the same vintage from single-blended Merlot or Shiraz cultivars. The principal goal of this study was to use these compounds for wine identification and to evaluate the correlation with antioxidant activity. High-performance liquid chromatography (HPLC) was used to determine catechin, epicatechin, rutin, quercetin, malvidin, peonidin, petunidin, cyanidin, delphinidin, pelargonidin, trans-resveratrol, gallic acid, chlorogenic acid, and p-coumaric acid. Spectrophotometric methods were employed to determine chromatic profile, total polyphenol content, antocyanins, proanthocyanidins, and antioxidant activity. There were some differences in the concentrations of phenolics for Shiraz and Merlot wines of 2009 vintage, including total polyphenols, antocyanidins, and proanthocyanidins. The analysis revealed a significantly higher antioxidant activity of Merlot than Shiraz and a strong correlation between antioxidant capacity and total polyphenol concentration.