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

Abstract

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.