Stereodifferentiation of 3-mercapto-2-methylpropanol in wine

Abstract

 3-Mercapto-2-methylpropanol, an odorous compound recently identified in red wines, was extracted from a red wine variety, using a low-temperature vacuum distillation coupled with a specific reversible thiol capture. The analysis of the diacetylated wine extract by enantioselective multidimensional gas chromatography with mass spectrometry detection revealed the presence of only one enantiomer, (R)-3-mercapto-2-methylpropanol. Although both of the optical isomers are characterized by the same broth and sweat odour, they have very different odour thresholds. The amounts of (R)-3-mercapto-2-methylpropanol in young Cabernet-Sauvignon and Merlot wines can exceed its perception threshold, thus suggesting its contribution to the aroma of these wines.