Identification of a powerful aromatic component of <i>Vitis vinifera</i> L. var. sauvignon wines: 4‐mercapto‐4‐methylpentan‐2‐one

TLDR

p‑Hydroxymercuribenzoic acid (pHMB) reacts reversibly with thiols. The study established a thiol extraction method for wines based on the pHMB principle. Extracts from Vitis vinifera L. var.

Abstract

Abstract p ‐Hydroxymercuribenzoic acid (pHMB), reacts reversibly with thiols. Using this principle, an extraction method of the thiols present in wines has been established. Injecting the extracts from Vitis vinifera L. var. Sauvignon wines on to a gas‐chromatographic column using the purge and trap technique and a flame photometric detector enabled us to discover some sulphur compounds present in wines from this cultivar. On several capillary columns of different polarities, one of the peaks possesses the same retention time as the potent odourant, 4‐mercapto‐4‐methylpentan‐2‐one, which evokes odours of box tree and cat urine. The identification of this compound in Sauvignon wines was confirmed by mass spectrometry. These results confirm previous work obtained by coupling gas chromatography and olfactometry, and show that this thiol is present in Sauvignon wines. The perception threshold of this compound in water and in wine is very low (close to 0.1 ng/1 and 3 ng/1s respectively) and despite its low concentration in Sauvignon wines, 4‐mercapto‐4‐methylpentan‐2‐one seems to play a major role in the varietal aroma of the wines from this cultivar.