INFLUENCE OF SOME TECHNOLOGICAL PRACTICES ON THE QUANTITY OF RESVERATROL IN WINE

A study of the effects of some perfermentative and fining practices on the resveratrol concentration in wine was carried out. The trans- and cis-resveratrol contents in a red wine obtained using must hyperoxida tion were reduced to about 50% compared with those of control wines; t his decrease was greater than that observed for total phenols and cate chins. In contrast, sparging the red grapes with SO2 and ascorbic acid before crushing them resulted in the trans-resveratrol concentration being greater than that of the control wines. Moreover the amounts of trans- and cis-resveratrol in commercial and synthetic wines were dete rmined before and after addition of charcol, polyvinylpoly-pyrrolidone (PVPP), bentonite, casein, gelatine, and two inert materials, cellulo se and diatomaceous earth (kiesel-gur), used as a filter aid. The resu lts showed that PVPP, charcoal and casein were more effective at remov ing trans- and cis-resveratrol both in synthetic wine and in commercia l wines. In all the wines tested the other fining agents gave a limite d decrease (2-5%) of trans- and cis-resveratrol. After charcoal and PV PP treatments, significant correlations were observed between the perc entage of residual resveratrol and the total phenols in the wines.