Catechin and Epicatechin Concentrations of Red Wines: Regional and Cultivar-Related Differences

Abstract

Employing gradient elution HPLC with direct injection of 20 µL of sample and diode array detection, the (+)-catechin and (-)-epicatechin concentrations were determined in >800 red wines from different wine-producing regions. The concentrations of both were highest in wines vinted from Pinot noir in all regions where this cultivar is grown, with red Burgundy and Canadian wines having the highest concentrations. Among wines vinted exclusively or predominantly from Cabernet Sauvignon, the highest catechin concentrations were found in wines from Washington State and Bordeaux (Medoc) with highest values for epicatechin in wines from Bordeaux and Canada. Next to wines from Pinot noir, those from Merlot had the highest in concentrations and wines from Shiraz the lowest. The ratio catechin: epicatechin showed considerable variation among the different cultivars, highest values for this ratio being found in wines from Pinot Noir and lowest in wines from Shiraz. Regression analysis revealed a variable but significant relationship between the two compounds, with the correlation coefficient ranging between 0.460 (Rhône Valley) to 0.917 (Oregon Pinot noir). Their relationship demonstrated a significant independent component, probably a consequence of genetic factors determining their concentrations in individual cultivars. However, their distribution is reminiscent of the pattern shown by resveratrol free isomers, suggesting that, in addition to cultivar, fungal pressure and climatic stress may promote their synthesis by Vitis vinifera.