EFFECT OF ENOLOGICAL PRACTICES ON THE RESVERATROL ISOMER CONTENT OF WINE

Resveratrol (trans-3,5,4'-trihydroxystilbene) is a phytoalexin produce d by grapevines in response to fungal infection, particularly to Botry tis cinerea, the causal organism for gray mold. This compound is known to occur in grapes as well as in wine and claimed to protect against heart diseases. Two factors that can modify resveratrol levels in wine were studied here: (1) the influence of classical white or red winema king practices and (2) the effect of grape Botrytis levels on the resv eratrol content of wines. Analysis of resveratrol was carried out by H PLC and GC-MS. Maceration on the grape skins increased the extraction of resveratrol by ca. 10-fold compared to nonmacerated wines. Paradoxi cally, lower concentrations of resveratrol were observed in wines made from highly Botrytis infected grapes than in those vinted from health y and moderately infected grapes. Finally, this study has clearly esta blished the presence of high quantities of the cis isomer of resveratr ol in,wine, a form only slightly detectable in grapes.