P. Jeandet et al., EFFECT OF ENOLOGICAL PRACTICES ON THE RESVERATROL ISOMER CONTENT OF WINE, Journal of agricultural and food chemistry, 43(2), 1995, pp. 316-319
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.