 IVES 9 IVES Conference Series 9 Alternative fate of varietal thiols in wine: identification, formation, and enantiomeric distribution of novel 1,3-oxathianes

Alternative fate of varietal thiols in wine: identification, formation, and enantiomeric distribution of novel 1,3-oxathianes

Abstract

AIM: This study aimed to explore an alternative fate of varietal thiols by identifying and characterising cis-2-methyl-4-propyl-1,3-oxathiane (cis-2-MPO) and cis-2,4,4,6-tetramethyl-1,3-oxathiane (cis-TTMO) in wine. Elucidating these new pathways could aid in explaining the loss of varietal thiols and would further our understanding of the stereochemical relationships between oxathianes and varietal thiols.

METHODS: GC-MS was used to identify cis-2-MPO,1 and a stable isotope dilution assay (SIDA) was developed to quantify its enantiomers after separation with a chiral β-cyclodextrin GC column.2 Varietal thiols and their enantiomers were analysed by SIDA with HPLC-MS/MS to determine their relationship with cis-2-MPO. Production of cis-2-MPO and its correlation with 3-SH, 3-SHA, and acetaldehyde was studied by profiling the evolution of these volatiles during alcoholic fermentation (AF) of Sauvignon blanc (SB) juice fermented with J7, VIN13, and their co-inoculum.3

RESULTS: cis-2-MPO, derived from 3-SH and acetaldehyde, was identified and then measured at up to 460 ng/L (equivalent to 385 ng/L of 3-SH) in a set of wines. Analysis of (2R,4S)-2-MPO and (2S,4R)-2-MPO, arising from thiol enantiomers (3S)-3-SH and (3R)-3-SH, showed respective concentrations of up to 250 and 303 ng/L. The enantiomeric ratio of (2R,4S)-/(2S,4R)-2-MPO was 43:57 whereas that of (3S)-/(3R)-3-SH in the same wines was 51:49.2 Strong correlations were revealed for both 3-SH and cis-2-MPO and their related enantiomeric pairs.The AF study showed cis-2-MPO was produced from an early stage of AF and reached a peak of 847 ng/L (VIN13 ferment) before gradually declining to 50-65 ng/L. Its evolution profile was identical to that of acetaldehyde and 3-SHA, with moderate to strong correlations found for the analytes.Additionally, cis-TTMO, derived from 4-MSPOH and acetaldehyde, was identified in wine as a single enantiomer at concentrations of up to 28 ng/L (equivalent to 23 ng/L of 4-MSPOH). An aroma detection threshold of 14.9 µg/L was determined for cis-TTMO, and this new volatile was described as ‘citrus’, ‘green’, ‘sweet/caramel’, and ‘mango’, shifting toward ‘onion/sweaty’ and ‘sulfurous’ at higher concentrations.2

CONCLUSIONS

The knowledge gained helps rationalise the fate of varietal thiols via the production of oxathianes in wine, and reveals the stereochemical links between these related compounds. A chemical formation pathway to oxathianes was verified and may also apply to other thiols bearing the 1,3-sulfanylalkanol substitution through the reaction with acetaldehyde.

DOI:

Publication date: September 13, 2021

Issue: Macrowine 2021

Type: Article

Authors

Xingchen Wang

Department of Wine Science and Waite Research Institute, The University of Adelaide (UA), PMB 1, Glen Osmond, SA 5064, Australia,Liang, CHEN, Université de Bordeaux, Unité de Recherche Œnologie, EA 4577, USC 1366 INRAE, Institut des Sciences de la Vigne et du Vin, 33882, Villenave d’Ornon cedex, France Dimitra L., CAPONE, Department of Wine Science and Waite Research Institute, Australian Research Council Training Centre for Innovative Wine Production, UA, PMB 1, Glen Osmond, SA 5064, Australia Aurélie, ROLAND, SPO, Univ Montpellier, INRAE, Institut Agro, Montpellier, France David W., JEFFERY, Department of Wine Science and Waite Research Institute, Australian Research Council Training Centre for Innovative Wine Production, UA, PMB 1, Glen Osmond, SA 5064, Australia

Contact the author

Keywords

3-sulfanylhexan-1-ol, 4-methyl-4-sulfanylpentan-2-ol, acetaldehyde, chiral stationary phase, odour detection threshold, sauvignon blanc, stable isotope dilution assay, gas chromatography–mass spectrometry

Citation

Intravarietal diversity: an opportunity for climate change adaptation

Merlot grapevine is the second wine cultivar most planted in the world and especially in the Bordeaux wine region. This cultivar has many advantages in producing high quality wine; however, in the last decade, climate change has increased the sugar concentration in berries at harvest and shortened the maturation cycle. If this has been up to now a great opportunity to improve wine quality profile, we are touching the tipping point. High sugar concentration at harvest induces high alcool content in wine which can negatively impact wine quality. There are many viticultural and oenological practices possible to limit this effect. In this study we focus on plant material through intra-varietal diversity of Merlot cultivar.

Un Système d’Informations à Références Spatiales sur le Vignoble. Un outil performant d’aide aux recherches sur la caractérisation des terroirs viticoles

The “Terroirs d’Anjou” project led by the Agronomy sector of the Vine and Wine Research Unit of the INRA center in Angers aims to characterize the viticultural terroirs in a study area which includes 29 municipalities in the Maine et Loire and cuts across the Anjou, Coteaux du layon and Coteaux de l’Aubance appellation areas.

Grapevine, berry and soil Indicators to manage minimal irrigation strategy in semi-arid conditions: example of Grenache noir (Vitis vinifera L.)

Context and purpose of the study. Climate change in many Mediterranean wine-growing regions is resulting in lower rainfall and higher reference evapotranspiration, generally leading to reduced water availability for vines.

Determination of selected phenolics, carotenoids and norisoprenoids in Riesling grapes after treatment against sunburn damage

Riesling represents the most widely cultivated grape variety in Germany and is therefore of particular economic interest. During recent years an increase in the petrol-note as well as in undesirable bitter and adstringent notes has been reported. These changes are most likely linked to increasing temperature and sunlight exposure of grapes due to climate changes.
The “petrol note” is caused by the formation of the C13-norisoprenoid 1,1,6-trimethyl-1,2-dihydronaphthalin (TDN), which originates from acid-labile precursors formed by the carotenoid degradation in the grape.

What happens with the glutathione during winemaking and the storage of the wine?

We tried to give a part of the answer to this question by monitoring glutathione during winemaking and storage. The novelty of our approach is to quantify simultaneously the three known forms of glutathione: free glutathione (GSH), oxidized form (GSSG) and glutathione-S-sulfonate (GSSO3H).