Effect of Winery Yeast Lees on Touriga Nacional Red Wine Color and Tannin Evolution

• Autor(a) principal: Rodrigues, Ana
• Data de Publicação: 2013
• Outros Autores: Ricardo-da-Silva, Jorge M., Lucas, Carlos, Laureano, Olga
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.5/25907
• topic: red wine; yeast lees; color; proanthocyanidins; mannoproteins

Red wine aging on lees is a w inemaking practice u sed to achieve more rounded and less astringent wines. In two different trials, external yeast lees were added to a red wine and their effects on wine color and tannin evolution during aging were studied. Results indicated that the addition of yeast lees did not affect color stabilization during the studied period. Color compounds a nd condensed tannins were rapidly adsorbed to t he yeast lees at the beginning of the experiment. There was a retarding effect on proanthocyanidin polymerization reaction by the addition of yeast lees, leading to the maintenance of low and medium molecular weight tannins in solution. Two different interactions were observed: first, proanthocyanidin adsorption by the yeast lees, primarily ones with the highest polymerization degree, and second, the retarding of proanthocyanidin polymerization, likely by the mannoproteins released by yeast lees. The age of the yeast lees was a factor in mannoprotein release and its effect in wine