Molecular and Sensory Fingerprints of Volatile Polyfunctional Thiols in Riesling Wines

Despite their apparent relevance to Riesling wine aroma, volatile polyfunctional thiols remain understudied. This work profiles thiols in a collection of Riesling wines through analytical and sensory approaches. Heart-cutting multidimensional gas chromatography mass spectrometry/olfactometry screening revealed 13 odorous zones of high sensorial relevance, with four thiols unequivocally identified as 3-sulfanylhexan-1-ol, ethyl 3-sulfanylpropionate, ethyl 2-sulfanylpropionate, and trans-2-methyl-3-tetrahydrofuranthiol. Five additional candidate thiols with corresponding odorous zones were confirmed by ultrahigh-performance liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry (UHPLC Orbitrap HRMS). UHPLC Orbitrap HRMS also allowed the quantitation of 12 thiols, as well as the detection of two new monoterpenoid thiols, 1-p-menthene-8-thiol and trans-p-menthane-3-one-8-thiol, in Vitis vinifera wine for the first time. Their odor detection thresholds in model wine were determined as 0.076 and 22.9 ng/L, respectively. Further sensory evaluations demonstrated the contributions to "peachy" and "tropical" notes in Riesling wine through a combination of 3-sulfanylhexan-1-ol and 3-sulfanylheptan-1-ol.