 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

Effects of Silver Thiosulphate and Salicylic Acid on the long-term maintenance of the embryogenic callus of Vitis vinifera

New Plant Breeding Techniques (NPBTs) have the potential to revolutionize the genetic improvement of grapevine. However, the practical application of these techniques is limited by several challenges, such as the difficulty in generating embryogenic calluses, maintaining their competence during in vitro cultivation, and regenerating plants without defects. To overcome these challenges, we conducted a study to test the effect of two treatments on callus cultures derived from different grapevine varieties, with and without embryogenic competence. The tested substances were Silver Thiosulphate (STS) an ethylene inhibitor, and Salicylic Acid (SA), an elicitor with different effects depending on the concentration of use beyond the ethylene inhibitor activity.

Using a grape compositional model to predict harvest time and influence wine style

Linking wine composition to fruit composition is difficult due to the numerous biochemical pathways and substrate transformations that occur during fermentation

UHPLC-HRMS analysis for the evaluation of formation and degradation of polysulfides in wine

The contribution of sulfur compounds to wine aroma has been studied for several years, as their role can be either positive, contributing to the fruitiness and typicity of some white wines like Sauvignon blanc, or negative when related to off-flavours caused by H2S.

Coping with heatwaves: management strategies for berry survival and vineyard resilience

Climate change is leading to an increase in average temperature and in the frequency and severity of heatwaves that is already significantly affecting grapevine phenology and berry composition (Webb et al., 2010). This is compounded by water stress, which is well known to increase the vulnerability of grapevines and berries to heatwaves. In hot climate regions like australia, grape production is only possible due to relatively secure supplies of water for irrigation. However, the upper temperature limits for berry survival of well-watered grapevines remains to be tested.

Phenological stage dependency of Cabernet Sauvignon and Grenache response to water and nutrient limitation

As the frequency and intensity of drought events increase, understanding the mechanisms of plant resilience to water deficit is crucial. To maintain an appropriate plant yield, a common practice is the application of high amounts of fertilizers with negative environmental impacts. The single and combined effect of water deficit and nutrient availability, namely nitrogen (N) and potassium (K), in Vitis Vinifera L. cv. Cabernet Sauvignon and Grenache was evaluated. Two-year-old grapevine plants grafted on SO4 rootstock were transferred in pots under semi-environmental conditions. During the growing season, plants were either maintained well-watered (100% ETc) or subjected to a controlled water deficit irrigation (33% ETc).