Proantocianidinas da uva e do vinho: isolamento, caracterizacao quimica e quantificacao. Sua importancia em enologia

Grape and wine proanthocyanidins have been fractionated on C_1_8 Sep-Pak cartridges into three fractions containing respectively monomeric flavan-3-ol (catechins), oligomeric proanthocyanidins (degree of polymerisation ranging from 2 to 12-15) and polymeric proanthocyanidins (degree of polymerisation >12-15). Several parameters mostly affecting the precision and accuracy of vanillin assay were optimised. On the basis of the separation method and modified vanillin assay, proanthocyanidins in some grapes and wines were quantified. We have further studied the extraction efficiency of various solvents on grape seed proanthocyanidins. In addition, the isolation and purification of some individual dimeric and trimeric procyanidin, and the mixture product of oligomeric procyanidin and that of polymeric procyanidin, and the mixture product of oligomeric procyanidin and that of polymeric procyanidin, from gape seed, on a preparative scale, were described. Finally, we have studied the transfer of proanthocyanidins during wine-making, i.e. the release of these compounds from different parts of grape into wine, their evolution during fermentation and early post-fermentation, and also the effect of different types of wine making technologies on proanthocyanidins contents in red winesAvailable from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1249-074 Lisboa, Portugal / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga