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…

Grape must quality and mesoclimatic variability in Fruška Gora wine-growing region, Serbia

The Fruška Gora mountain is a traditional wine-growing region in Serbia situated in the Pannonian Basin. Due to such a position, the vicinity of the Danube River and the presence of concave configuration, it is suitable for grape production. This paper provides analyses of spatial variations in meteorological parameters and grape juice quality within Fruška Gora wine region over three consecutive vintages (2018-2020). The examined period can be defined as warm with cool nights during September (AVG 18,9°C; GDD 1918°C; CI 12°CF) and with the presence of mesoclimatic variability. The East part of the study area was somewhat drier and hotter compared to other parts of the region. The analyses of grape must samples (190 in total) of five cultivars (Cabernet-Sauvignon, Merlot, Chardonnay, Sauvignon blanc and Grašac (Welschriesling)) commonly grown across the region (19 sites), were performed using Fourier Transform Infrared Technology (FTIR). Among all cultivars, Sauvignon blanc was harvested first in the East area (DOY=246±5, GDD at harvest=1552±74, 22.2±0.7 °Brix), while the latest harvest was recorded for Cabernet-Sauvignon in the West (DOY=283±5, GDD at harvest=1936±187, 23.4±1.0 °Brix ). Both the red and white cultivars had higher acidity and YAN in the grape must if the vines were grown in the North and East compared to South and West areas. According to PCA analysis, Grašac showed the lowest variation in grape must chemical composition. Thus, the results confirm that Grašac is the most stable cultivar in Fruška Gora. All monitored cultivars reached technological fruit ripeness by the end of the growing season. However, it was difficult to reach full ripeness of red cultivars, mostly beacuse of uncoupling of technolocical and phenolic ripeness. Thus, Cabernet-Sauvignon had higher variations in GDD sums at harvest compared to other cultivars, which probably increased variations in grape must quality.

Local adaptation tools to ensure the viticultural sustainability in a changing climate

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.19.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...

Effect of the commercial inoculum of arbuscular mycorrhiza in the establishment of a commercial vineyard of the cultivar “Manto negro

The favorable effect of symbiosis with arbuscular mycorrhizal fungi (AMF) has been known and studied since the 60s. Nowadays, many companies took the chance to start promoting and selling commercial inoculants of AMF, in order to be used as biofertilizers and encourage sustainable biological agriculture. However, the positive effect of these commercial biofertilizers on plant growth is not always demonstrated, especially under field conditions. In this study, we used a commercial inoculum on newly planted grapevines of a local cultivar grafted on a common rootstock R110. We followed the physiological status of vines, growth and productivity and functional biodiversity of soil bacteria during the first and second years of 20 inoculated with commercial inoculum bases on Rhizophagus irregularis and Funeliformis mosseaeAMF at field planting time and 20 non-inoculated control plants. All the parameters measured showed a neutral to negative effect on plant growth and production. The inoculated plants always presented lower values of photosynthesis, growth and grape production, although in some cases the differences did not reach statistical significance. On the contrary, the inoculation supposed an increase of the bacterial functional diversity, although the differences were not statistically significant either. Several studies show that the effect of inoculation with AMF is context-dependent. The non-favorable effects are probably due to inoculation ineffectiveness under complex field conditions and/or that, under certain conditions, AMF presence may be a parasitic association. This puts into question the effectiveness of its application in the field. Therefore, it is recommended to only resort to this type of biofertilizer when the cultivation conditions require it (e.g., very low previous microbial diversity, foreseeable stress due to drought, salinity, or lack of nutrients) and not as a general fertilization practice.

Vineyards and clay minerals: multi-technique analytical approach and correlations with soil properties

Purpose of this research is to quantitatively assess the mineral component of vineyard soils, with particular attention to the mineralogical analysis of clays, which represent an element of high importance in the vineyard culture as well as in general agriculture. An X-ray diffraction (XRD) / thermogravimetric (TG) multi-technique analytical approach was developed, tested on soil samples taken from vineyards around the world. This codified analytical procedure was necessary to obtain precise qualitative and quantitative mineralogical data, globally comparable to distinguish the geopedological identity of the vineyards. Soil samples from vineyards of various locations were analysed, in very different geological conditions. The bulk-rock quantitative phase analysis (QPA) was obtained by the Rietveld method while the detailed composition of the clay-sized fraction was determined by modelling of the oriented X-ray diffraction patterns. The research provided a precise classification of the mineral component of soils, distinguishing the mineral phases of the clays and the so-called mixed-layer clay minerals. We found that the content in mixed layers can be directly correlated with the water retention and the cation exchange capacity ​​of the soil, while the presence of other clayey minerals and phyllosilicates in this research did not affect this CEC parameter, which codes the fertility level of the soils. The study demonstrates that terroir, in particular soils formed in complex or very different geological conditions, can only be effectively interpreted by properly analysing its mineral phases, in particular the mixed-layer clay component. These are characteristic abiotic ecological indicators, which may have specific eco-physiological influences on the plant.

Modeling island and coastal vineyards potential in the context of climate change

Climate change impacts regional and local climates, which in turn affects the world’s wine regions. In the short term, these modifications rises issues about maintaining quality and style of wine, and in a longer term about the suitability of grape varieties and the sustainability of traditional wine regions. Thus, adaptation to climate change represents a major challenge for viticulture. In this context, island and coastal vineyards could become coveted areas due to their specific climatic conditions. In regions subject to warming, the proximity of the sea can moderate extremes temperatures, which could be an advantage for wine. However, coastal and island areas are particular prized spaces and subject to multiple pressures that make the establishment or extension of viticulture complex.
In this perspective, it seems relevant to assess the potentialities of coastal and island areas for viticulture. This contribution will present a spatial optimization model that tends to characterize most suitable agroclimatic patterns in historical or emerging vineyards according to different scenarios. Thanks to an in-depth bibliography a global inventory of coastal and insular vineyards on a worldwide scale has been realized. Relevant criteria have been identified to describe the specificities of these vineyards. They are used as input data in the optimization process, which will optimize some objectives and spatial aspects. According to a predefined scenario, the objectives are set in three main categories associated with climatic characteristics, vineyards characteristics and management strategies. At the end of this optimization process, a series of maps presents the different spatial configurations that maximize the scenario objectives.