Trans-Resveratrol Concentrations in Berry Skins and Wines from Grapes Grown in Japan

Abstract

The resveratrol concentrations in 10 white, two pink and nine red wines, and in the skins of ripe and apparently healthy grapes of 16 white- and 20 pink- or red-skinned grape varieties grown in Japan (relatively humid and warm with heavy rainfall in the growing season) were determined by high pressure liquid chromatography with fluorescence detection. The resveratrol concentration in skins ranged from 0.5 (Pizzutello Bianco) to 14.1 (Mü11er-Thurgau) µg/g fresh skin, with an average of 4.12µg/g for the 36 skin samples, and that in wines from 1 (Delaware) to 244 (Cabernet Sauvignon) µg/L with an average of 81 µg/L for the 21 wine samples. These values are not markedly different from those in the literature pertaining to other grapegrowing and winemaking regions of the world. The average resveratrol concentration in red wines was about six-fold that in white wines. Little resveratrol (less than 0.01 µg/L) was found in grape juices. The effect of fermentation on the skins (maceration) on the resveratrol contents of wines was investigated. While no increase in resveratrol occurred during fermentation without skins, the resveratrol concentrations increased during fermentation on the skins. The rate of resveratrol extraction from skin to wine differed with grape variety and skin contact time.