Effect of bentonite fining on polyfunctional mercaptans and other volatile compounds in Sauvignon blanc wines

Bentonite fining is the most common process used in the wine industry to remove proteins from wine. Herein, the influence of fermentative and post-fermentative fining on aroma compounds found in Sauvignon blanc wines was studied. Sauvignon blanc musts from different vintages were fined using bentonite. Conventional enological parameters, together with more than 60 volatile compounds, including varietal thiols, were determined in the bottled wines. The results showed that bentonite fining was more effective in removing proteins from wine when carried out on finished wines. Several volatile compounds were influenced by bentonite fining depending on the tim­ing of addition and the vintage. Varietal thiols, key compounds of Sauvignon blanc wine aroma, were significantly reduced when the wines were fined with bentonite, particularly when fining took place during fermentation. Results suggest that bentonite fining of musts could damage the organoleptic quality and varietal character of Sauvignon blanc wines because of its impact on polyfunctional mercaptans