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Molecular and sensory characterization of the aging bouquet of Bordeaux red wines: influence of the stopper

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Molecular and sensory characterization of the aging bouquet of Bordeaux red wines: influence of the stopper

Emilia Suhas

Emilia SUHAS
ISVV-Institut des Sciences De la Vigne et du Vin (Francia)

Many aromatic compounds are involved in the aging bouquet expression of great red wines Their identification is a challenging task due to several drawbacks: the matrix complexity, the low concentration of impact compounds and the volume of wine required. The aim of this work was to develop a new strategy based on an accelerated reductive treatment (A.R.T.) of oak wood organic extracts with H2S to produce new thiols, in order to mimic what can happen in red wine during bottle aging.

Following this new approach, and through sensory analysis experiments, we demonstrated that the vanilla-like aroma of fresh oak wood was transformed into intense “meaty” nuances similar to those found in old but non-oxidized red wines. After optimization of the chemical reaction, the samples were analyzed by gas chromatography coupled with a pulsed flame photometric detector and olfactometry (GC-O-PFPD) to detect odorant zones reminiscent of the meaty nuances. One of them was identified as 2-methoxybenzenethiol by preparative multidimensional GC-GC-O-TOF MS in oak wood extracts and by GC-MS/MS (SRM mode) in red wines. Following the same strategy, five other thiols reminiscent of “meaty” nuances, including 2,5-dimethylfuran-3-thiol, 5-methyl-2-furfurylthiol, o-toluenethiol, 2,6-dimethylbenzenethiol and 2,6-dimethoxybenzenethiol were also identified, some of them for the first time in red wines. At the same time, we report the identification of 1-phenylethanethiol and 2-methyl-(3-methyldithio)-furan in old red wines.

We validated a quantification method by SPE GC-MS/MS to study their distribution in 67 young and old Cabernet Sauvignon wines between 2000 and 2016 from different appellations located in Napa Valley, Pauillac and Toscany. These results showed that the highest concentrations of thiols were found in the oldest wines and varied according to the growth. We determined the odor detection threshold of these compounds in model solution and a red wine and we demonstrated for the first time their contribution on the aroma of old red wines. inally, to complete this work, we studied the link between thiol compounds and their precursors released by oak during barrel aging and the influence of the choice of cork on the levels of these “meaty” thiols in a Bordeaux red wine aged 12 years in bottle. hese results highlight the influence of oak aging and the importance of a quality closure on the development of red wine meaty aromas during long-term aging.

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