Grape tannins are widely used adjuvants in winemaking. Their impact on color stability, mouthfeel and aroma profile has already been investigated but the possibility that grape tannins could also introduce the S-glutathionylated and S-cysteinylated precursors of 3-mercaptohexanol (3MH), was only recently proven.The identification of these precursors was achieved by applying LC-MS/MS experiments and comparing the mass spectra of natural samples with those obtained from synthetic reference compounds.Additionally, different grape tannins showed significantly different levels of the two precursors suggesting that the preparation protocol of the tannins and the grape tissue chosen could be crucial. This finding has opened a new avenue on the use of the grape tannins in winemaking to modulate wine aroma for such an important and studied class of molecules.In a second study, a preliminary experiment was designed to test for this hypothesis: pre-fermentative introductions of thiol precursors, via tannins addition, were carried out in several Mueller-Thurgau (17) and Sauvignon blanc (15) juices. The content of 3-mercaptohexano-l-ol and 3-mercaptohexyl acetate was measured in the finished wine.3-Mercaptohexanol and its acetate were higher in all the wines added with grape tannins as compared to those without tannins.This further result strengthens the idea that pre-fermentative addition of oenological tannins could be used to modulate the level of tropical thiols.

Grape tannins to modify wine tropical flavor

248th National Meeting (2014)

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