Resveratrol Content in Some Tuscan Wines

Reverse phase high performance liquid chromatography was used to determine the trans-resveratrol concentration in 40 Tuscan wines. It ranged from 0.3 to 2.1 mg/L in the 32 red wines and had a maximum of 0.1 mg/L in the 8 white wines tested, thereby confirming previous reports of the higher amounts of resveratrol of red wines. Both the cis- and trans- isomers of resveratrol were detected in all tested samples, a finding confirmed by a cross-check using HPLC and high resolution gas chromatography. Cis-resveratrol levels were comparable to those of the trans- isomer. They ranged from 0.5 mg/L to 1.9 mg/L in red wines and had a maximum of 0.2 mg/L in white wines. These findings and the partitioning of resveratrol in the various parts of the grape berry suggest that the reported differences depend on differences in wine-making techniques.