Role of viticultural factors on stilbene concentrations of grapes and wine.

Stilbenes are phenolics that can be found in different grapevine organs, such as berries, leaves, canes and roots. Stilbenes act as antifungal compounds since they are synthesized by the plant in response to pathogen attack. Other abiotic elicitors, such as ultraviolet rays and heavy metals, can trigger stilbene production. Many stilbenic compounds have been detected in grapes and wine (resveratrol, piceid, viniferins, astringin, etc.). The latest stilbene to be analyzed is piceatannol (or astringinin). Stilbene synthesis in grapes depends on different viticultural factors such as the grape variety, the environment and cultural practices. Concerning grape variety, red berry-grapes have higher stilbene levels than white berry-grapes. With regard to climate, preliminary results suggest a positive correlation between vineyard elevation and stilbene grape concentrations. Quality-oriented cultural practices produce grapes with high levels of stilbenes.