Exploring the Equilibrium between Glut3SHal and Glut3SH-SO₃: A Method for the Quantification of These Compounds in...

3S-Gluthathionylhexanal (glut3SHal) is an early precursor to the important wine aroma compound 3-sulfanylhexan-1-ol (3SH), imparting tropical passion fruit aromas, even at trace concentrations. In wine, glut3SHal occurs in equilibrium with its bisulfite adduct (glut3SH-SO₃), challenging its quantification. To circumvent the issues encountered when attempting to describe the equilibrium between these compounds, a method for their quantification in wine samples was developed. Separation of glut3SHal and glut3SH-SO₃ using solid-phase extraction followed by oxime derivatization and analysis via liquid chromatography-mass spectrometry allowed for measurement of both compounds in wine samples. Analysis of commercial Sauvignon Blanc wines using the developed method confirmed that glut3SH-SO₃ is the major species in the wine matrix. The method developed in this work will enable further exploration of the relationship between glut3SHal and glut3SH-SO₃ and their contribution to production of 3SH in wines. There is potential to extrapolate this work to explore other aldehyde-sulfonic acid equilibria in foods and beverages.