IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 New insights on thiol precursors catabolism by yeast during wine fermentation: identification of the N-Acetyl-L-Cysteine conjugate

New insights on thiol precursors catabolism by yeast during wine fermentation: identification of the N-Acetyl-L-Cysteine conjugate

Abstract

Understanding the catabolism of thiol precursors is essential for understanding the revelation of varietal thiols in wine. For many years, knowledge of these precursors has been limited to the S-conjugates of glutathione, cysteine (Cys3SH) and the dipeptides g-GluCys and CysGly, without being able to explain the full origin of 3-sulfanylhexan-1-ol (3SH) in wines. Cysteine was the one considered as the final intermediate before the revelation of 3SH by yeast. Inspired by the glutathione detoxification pathway of xenobiotics, we identified the 3-S-(N-Acetyl-Cysteinyl)hexan-1-ol (NAC3SH) as a new metabolite, by developing (a) a dedicated organic synthesis strategy, (b) a targeted LC-MS/MS analysis method and (c) filiation studies under oenological conditions.In practice, we synthesized NAC3SH by Michael addition of N-Acetyl-L-Cysteine onto trans-2-hexenal in 50/50 water/acetonitrile followed by reduction with NaBH4 in situ. After purification by preparative HPLC, the two diastereomers of NAC3SH were successfully isolated. Characterization was done by both 1D and 2D homonuclear 1H and heteronuclear 1H /13C NMR spectroscopy and quantification by 1D 1H NMR (qNMR). An analytical method for NAC3SH was developed by LC-MS/MS using Cys3SH-d2 as internal standard. The resolution of the two diastereomers could not be achieved under our conditions and they were therefore analyzed in 50/50 equimolar mixture. The method has been validated and showed very satisfactory analytical performances (accuracy = 102%, linearity: R2 = 0.976, LOQ = 6.9 µg/L, LOD = 23 µg/L, repeatability: CV).

DOI:

Publication date: June 23, 2022

Issue: IVAS 2022

Type: Article

Authors

Dournes Gabriel¹, Sachot Somaya¹, Le-Guernevé Christine¹, Suc Lucas1, Mouret Jean-Roch¹ and Roland Aurélie¹  

¹SPO, Univ Montpellier, INRAE, Institut Agro, Montpellier, France

Contact the author

Keywords

thiol precursors, varietal thiol, grape, wine

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Aromatic characterization of Moscato Giallo by GC-MS/MS and stable isotopic ratio analysis of the major volatile compounds

Among the Moscato grapes, Moscato Giallo is a winegrape variety characterized by a high content of free and glycosylated monoterpenoids, which gives very aromatic wines. The aromatic bouquet of Moscato Giallo is strongly influenced by the high concentration of linalool, geraniol, linalool oxides, limonene, α-terpineol, citronellol, HO-trienol, HO-diols, 8-Hydroxylinalool, geranic acid and β-myrcene, that give citrus, rose, and peach notes.

Read More

Evaluation of the impact of different amelioration techniques on the chemical composition and sensory characteristics of smoke impacted wines

AIM: The increasing incidences of wildfires in wine grape growing regions pose a significant risk. Persistent exposure to smoke can compromise the quality and value of wine grapes and adversely affect wines made from smoke exposed grapes.

Read More

IMPACT OF NEW BIO STIMULANTS ON GRAPE SECONDARY METABOLITES UNDER CLIMATE CHANGE CONDITIONS

In a context of climate change and excessive use of agrochemical products, sustainable approaches for environmental and human health such as the use of bio stimulants in viticulture represent a potential option, against abiotic and biotic threats. Bio stimulants are organic compounds, microbes, or a combination of both, that stimulate plant’s vital processes, allowing high yields and good quality products. In vines, may trigger an innate immune response leading to the synthesis of secondary metabolites, key compounds for the organoleptic properties of grapes and wines.

Read More

Impact of the pre-fermentative addition of enological adjuvants on the development of UTA in wines

During alcoholic fermentation and wine aging, indole-3-acetic acid (IAA) can degrade into 2-aminoacetophenone (AAP). The presence of reasonable amount of AAP in wines is regarded as the main cause of untypical ageing

Read More

Influence of the unité de terroir base on the typicity of winesin the AOC Priorat in Tarragona

L’AOC Priorat, située derrière les montagnes du pré littoral de Tarragone, se caractérise par un climat méditerranéen avec une tendance à la continentalité et très peu de précipitation pendant le cycle végétatif. Les sols sont secs, pauvres et caillouteux, formés par des schistes. Au cours des années 2000 et 2001, une étude de l’influence du terroir sur la typicité des vins du Priorat a été réalisée en prenant comme référence trois cépages cultivés dans différentes parceIles pour mesurer l’effet du terroir et du mésoclimat sur la qualité des vins:

Read More