Determination of Major Phenolic Compounds of Grape Juice and Wine of Different Geographic Origins

Trans-resveratrol, quercetin, and epicatechin are natural polyphenolic substances with a wide range of biological activities, including anti-oxidant and anti-cancer properties. The compositions and levels of these chemicals were determined in grape (Vitis vinifera) juice and wine of different geographic origins. Significant differences in Hunter color values, pH, total acidity, and ethanol and free sugar contents, were found depending on both the nature and country of processing. Overall, trans-resveratrol and quercetin levels in wines were higher than in juices, indicating that wine is a rich source of these chemicals. Significant differences in the content and composition of epicatechin were found to depend on processing procedures, country of origin, and cultivar. This information may be useful to grape breeders and manufacturers of wine or juice.