Terroir 2020 banner
IVES 9 IVES Conference Series 9 Intraregional profiles of varietal thiols and precursors in Sauvignon Blanc juices and wines from the Adelaide Hills

Intraregional profiles of varietal thiols and precursors in Sauvignon Blanc juices and wines from the Adelaide Hills

Abstract

Aims: To investigate the intraregional variation of varietal thiol precursors and free thiols in Sauvignon blanc grape juices and experimental wines arising from the Adelaide Hills Geographical Indication (GI) in South Australia.

Methods and ResultsVitis vinifera L. cv Sauvignon blanc grape parcels (n = 21, approx. 8 kg each, encompassing 5 clones) were hand harvested from different blocks within seven commercial vineyards in the Adelaide Hills GI during the 2018 vintage. Parcels were divided into subsets for winemaking and freezing experiments. Amino acid (AA) and thiol precursor concentrations in juice were determined using high performance liquid chromatography (HPLC) with fluorescence detection and stable isotope dilution assay (SIDA) using HPLC with tandem mass spectrometry (MS/MS), respectively, and free thiols in wine were quantified by SIDA with HPLC-MS/MS, after derivatisation with 4,4’-dithiodipyridine. Intraregional variations in grape ripeness were evident according to total soluble solids content, pH, and titratable acidity, even within single locations or for the same clones. Significant differences in the glutathionylated precursor to 3-sulfanylhexan-1-ol (3-SH) were found among several locations whereas for the cysteinylated variant of 3-SH, one location was distinct from the rest. Variation in precursor concentrations was also noted from different blocks within a single vineyard location but was not dependent on grape ripeness. Fermentations progressed without any obvious relationship to location, and wines that were high in 3-SH were also usually high in 3-sulfanylhexyl acetate (3-SHA). One location had significantly higher levels of thiols in wine despite the juice not being the highest for grape-derived precursors, and also gave a substantial concentration of 4-methyl-4-sulfanylpentan-2-one in comparison to other locations within the GI. The AA profile of juices was found to vary according to location, and certain AAs were strongly correlated to thiol precursor concentrations, but relationships of AAs with free thiols in wine were generally weak. Additionally, enhancements in the concentrations of precursors in juice (up to 19-fold) and free thiols in wine (up to 10-fold) were revealed from freezing whole grape bunches in contrast to using fresh juice.

Conclusions: 

Intraregional variation was noted for thiols in wine, and precursors and amino acids in juice, for 21 Sauvignon blanc samples collected from within the Adelaide Hills region. The effects of terroir were implicated in explaining the differences in grape composition, and the potential interactions among grape amino acids and thiol precursors in berries and thiols in wine were revealed.

Significance and Impact of the Study: Sauvignon blanc is a significant variety produced in the Adelaide Hills GI but no information was available on the effects of location within the GI on grape and wine composition with respect to varietal thiols. This was the first study of intraregional variations of thiol precursors, amino acids, and free thiols in Sauvignon blanc juices and wines that were produced in a consistent manner. A remarkable enhancing effect of freezing was noted for thiol precursors in juice, and importantly, free thiols in wine.

DOI:

Publication date: March 17, 2021

Issue: Terroir 2020

Type: Video

Authors

Liang Chen1,a, Dimitra L. Capone1,2, Emily L. Nicholson3, David W. Jeffery1,2*

1 School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, PMB 1 Glen Osmond, SA 5064, Australia
2 Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide, PMB 1 Glen Osmond, SA 5064, Australia
3 CSIRO Agriculture and Food, Locked Bag 2, Glen Osmond, SA 5064, Australia

aPresent address: Institut des Sciences de la Vigne et du Vin, Université de Bordeaux, 210 chemin de Leysotte CS 50008, 33882 Villenave d’Ornon Cedex, France

Contact the author

Keywords

List of different keywords (keyword1, keyword2, keyword3)

Tags

IVES Conference Series | Terroir 2020

Citation

Related articles…

Protected Designation of Origin (D.P.O.) Valdepeñas: classification and map of soils

The objective of the work described here is the elaboration of a map of the different types of vineyard soils that to guide the famers in the choice of the most productive vine rootstocks and varieties. 90 vineyard soils profiles were analysed in the entire territory of the Origen Denominations of Valdepeñas. The sampling was carried out in 2018 (June to October) by making a sampling grid, followed by photointerpretation and control in the field. The studied soils can be grouped into 9 different soil types (according to FAO 2006 classification): Leptosols, Regosols, Fluvisols, Gleysols, Cambisols, Calcisols, Luvisols and Anthrosols. A map showing the soil distribution with different type of soils has been made with the ArcGIS program. Regarding to the choice of rootstock, Calcisoles are soils with a high active limestone content, so the rootstocks used in these soils must be resistant to this parameter; Luvisols are deep soils with high clay content, so they will support vigorous rootstocks. Because the cartographic units are composed of two or more subgroups, with are associated in variable proportions, 9 different soil associations have been established; Unit 1: Leptosols, Cambisols and Luvisols (80%, 15% and 5% respectively); Unit 2: Cambisols with Regosols and Luvisols (40%, 30% and 30% respectively); Unit 3: Cambisols and Gleysols with Regosols (40%, 40% and 20% respectively); Unit 4: Regosols with Cambisols, Leptosols and Calcisols (40%, 30%, 15% and 15% respectively); Unit 5: Cambisols, Leptosols, Calcisols and Regosols (25% each of them); Unit 6: Luvisols with Cambisol and Calcisols (80%, 10% and 10% respectively); Unit 7: Luvisols and Calcisols with Cambisols (40%, 40% and 20% respectively); Unit 8: Calcisols with, Cambisols and Luvisols (80%, 10% and 10% respectively); Unit 9: Anthrosols. These study allow to elaborate the first map of vineyard soils of this Protected Designation of Origin in Castilla-La Mancha.

Characterization of variety-specific changes in bulk stomatal conductance in response to changes in atmospheric demand and drought stress

In wine growing regions around the world, climate change has the potential to affect vine transpiration and overall vineyard water use due to related changes in atmospheric demand and soil water deficits. Grapevines control their transpiration in response to a changing environment by regulating conductance of water through the soil-plant-atmosphere continuum. Most vineyard water use models currently estimate vine transpiration by applying generic crop coefficients to estimates of reference evapotranspiration, but this does not account for changes in vine conductance associated with water stress, nor differences thought to exist between varieties. The response of bulk stomatal conductance to daily weather variability and seasonal drought stress was studied on Cabernet-Sauvignon, Merlot, Tempranillo, Ugni blanc, and Semillon vines in a non-irrigated vineyard in Bordeaux France. Whole vine sap flow, temperature and humidity in the vine canopy, and net radiation absorbed by the vine canopy were measured on 15-minute intervals from early July through mid-September 2020, together with periodic measurement of leaf area, canopy porosity, and predawn leaf water potential. From this data, bulk stomatal conductance was calculated on 15-minute intervals, and multiple regression analysis was performed to identify key variables and their relative effect on conductance. Attention was focused on addressing multicollinearity and time-dependency in the explanatory variables and developing regression models that were readily interpretable. Variability of vapor pressure deficit over the day, and predawn water potential over the season explained much of the variability in conductance, with relative differences in response coefficients observed across the five varieties. By characterizing this conductance response, the dynamics of vine transpiration can be better parameterized in vineyard water use modeling of current and future climate scenarios.

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.

Bioclimatic shifts and land use options for Viticulture in Portugal

Land use, plays a relevant role in the climatic system. It endows means for agriculture practices thus contributing to the food supply. Since climate and land are closely intertwined through multiple interface processes, climate change may lead to significant impacts in land use. In this study, 1-km observational gridded datasets are used to assess changes in the Köppen–Geiger and Worldwide Bioclimatic (WBCS)

Effects of graft quality on growth and grapevine-water relations

Climate change is challenging viticulture worldwide compromising its sustainability due to warmer temperatures and the increased frequency of extreme events. Grafting Vitis vinifera L.