TRANS-RESVERATROL CONCENTRATIONS IN BERRY SKINS AND WINES FROM GRAPESGROWN IN JAPAN

The resveratrol concentrations in 10 white, two pink and nine red wine s, and in the skins of ripe and apparently healthy grapes of 16 white- and 20 pink- or red-skinned grape varieties grown in Japan (relativel y humid and warm with heavy rainfall in the growing season) were deter mined by high pressure liquid chromatography with fluorescence detecti on. The resveratrol concentration in skins ranged from 0.5 (Pizzutello Bianco) to 14.1 (Muller-Thurgau) mu g/g fresh skin, with an average o f 4.12 mu g/g for the 36 skin samples, and that in wines from 1 (Delaw are) to 244 (Cabernet Sauvignon) mu g/L with an average of 81 mu g/L f or the 21 wine samples. These values are not markedly different from t hose in the literature pertaining to other grapegrowing and winemaking regions of the world. The average resveratrol concentration in red wi nes was about six-fold that in white wines. Little resveratrol (less t han 0.01 mu g/L) was found in grape juices. The effect of fermentation on the skins (maceration) on the resveratrol contents of wines was in vestigated. While no increase in resveratrol occurred during fermentat ion without skins, the resveratrol concentrations increased during fer mentation on the skins. The rate of resveratrol extraction from skin t o wine differed with grape variety and skin contact time.