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 gra pe cluster into wine was investigated. The Tinta Miuda red wines made by sk in fermentation, both with and without stem contact, were used in this stud y. Catechins, oligomeric and polymeric proanthocyanidins in all solid parts of the grape cluster before crushing, in the wines, and in the seeds and s tems isolated from pomace after fermentation, were quantified. Nearly half of extractable catechins and oligomeric proanthocyanidins in grape seeds we re transferred into wine, but grape seeds did not contribute polymeric proa nthocyanidins to the wine. From the stems, the great majority of extractabl e catechins, oligomeric and also polymeric proanthocyanidins were released into wine. Both grape skins and grape stems were important sources of polym eric proanthocyanidins for the wine. Although considerable amounts of catec hins, oligomeric and polymeric proanthocyanidins were extracted from solid parts of the cluster during fermentation, only small amounts of these compo unds were retained in wines.