Grape chemistry and the significance of resveratrol: An overview

An overview of the discovery of the stilbene, resveratrol, in grapes is presented. Factors affecting the concentration of resveratrol in grape skirt are presented, emphasizing the ephemeral nature of its occurrence. Resveratrol is a phytoalexin and synthesized only after appropriate stimulation. Once its function of disease resistance succeeds or fails, the concentration declines. On subsequent interaction with micro-organ isms or other inducers it can be resynthesized. Resveratrol in grape skin is readily transfered to red wine by fermentation alcohol extraction. It was also quantitatively recovered during the hot press extraction process typical of red or purple juice production. Concentrations of resveratrol in raisins was determined by light exposure during drying. Quercetin a flavonol component of grapes was found to be higher in red than in white wine and nor effectively extracted by the hot press process of purple juice production. Resveratrol was found in several nutraceutical products made from grape extracts.