Content of trans- and cis-resveratrol in Galician white and red wines

Content in resveratrol (trans and cis) present in commercial white and red wines of the five Galician Controlled Denomination of Origin (CDO Monterrei, CDO Rías Baixas, CDO Ribeira Sacra, CDO Ribeiro and CDO Valdeorras) has been determined by reversed-phase high-performance liquid chromatography (HPLC) with fluorimetric detection. The wines were filtered and directly injected, and also the samples were analyzed after the addition of two known amounts of the two standard isomers. The results obtained showed that the content in cis-resveratrol found in white and red wines ranged from 0.12 to 0.06 mg/L, respectively, whereas the concentration of trans-resveratrol was highest in the red wines (mean=12.68 mg/L), elaborated mainly from varieties such as Mencía, and practically null in the white wines (mean=2.51 mg/L), except in Godello and Albariño wines.