Analysis and Characterization of Wine Condensed Tannins Precipitated by Proteins Used as Fining Agent in Enology

Abstract

The effects of gelatins used as fining agents on the amount and nature of polyphenols removed from wine were studied. A red wine was treated with differently hydrolysed gelatins. Polyphenols were analyzed by fractogel chromatography followed by reversed-phase HPLC preceded by thiolysis for condensed tannins. The phenolic composition and content of wine were not significantly affected by gelatin fining treatments. Nevertheless, the polyphenols precipitated were characteristic. Gelatins preferentially removed high molecular weight galloylated proanthocyanidols. Proanthocyanidin precipitation was quite similar for all the gelatins examined except for the largest molecular weight protein which precipitated lower amount of proanthocyanidins with an additional selectivity for epigallocatechin-rich tannins.