Evolution of resveratrol and piceid contents during the industrial winemaking process of sherry wine.

In the Jerez region, the sherry winemaking process involves a stage of aging carried out in a dynamic system known as "soleras" and "criaderas". In the case of fino sherry, this aging takes place in the presence of a yeast film growing on the surface of the wine, which gives it a very specific character. In this work, the influence of the sherry elaboration process on resveratrol and piceid levels has been studied. With this purpose, the contents of resveratrol isomers and piceid during the main stages of the sherry wine production system, from maturation until bottling, were monitored during two vintages. The results showed that resveratrol contents of both the skin and juice, for Palomino fino grape, are very similar to those described for other white grape varieties. Sherry wine fermentation, clarification, cold stabilization, and filtration processes considerably affect resveratrol and piceid contents. However, biological aging has the most important influence, diminishing their contents by 80%. These results were confirmed in several tests performed in the laboratory, in which various factors that could affect the resveratrol contents during aging were taken into account (oxidative phenomena and a combination with acetaldehyde and "flor" biofilm growth).