Transfer of Catechins and Proanthocyanidins From Solid Parts of the Grape Cluster Into Wine

The transfer of catechins and proanthocyanidins from solid parts of the grape cluster into wine was investigated. The Tinta Miúda red wines made by skin fermentation, both with and without stem contact, were used in this study. Catechins, oligomeric and polymeric proanthocyanidins in all solid parts of the grape cluster before crushing, in the wines, and in the seeds and stems isolated from pomace after fermentation, were quantified. Nearly half of extractable catechins and oligomeric proanthocyanidins in grape seeds were transferred into wine, but grape seeds did not contribute polymeric proanthocyanidins to the wine. From the stems, the great majority of extractable catechins, oligomeric and also polymeric proanthocyanidins were released into wine. Both grape skins and grape stems were important sources of polymeric proanthocyanidins for the wine. Although considerable amounts of catechins, oligomeric and polymeric proanthocyanidins were extracted from solid parts of the cluster during fermentation, only small amounts of these compounds were retained in wines.