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 Results: Vitis 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.

Download the PDF

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…

Improved vineyard sampling efficiency using aerial NDVI

Random sampling is often considered to be the best protocol for fruit sampling because it is assumed to produce a sample that best represents the vineyard population.

Read More

Elucidating vineyard site contributions to key sensory molecules: Identification of correlations between elemental composition and volatile aroma profile of site-specific Pinot noir wines

The reproducibility of elemental profile in wines produced across multiple vintages has been previously reported using grapes from a single scion clone of Vitis vinifera L. cv. Pinot noir. The grapevines were grown on fourteen different vineyard sites, from Oregon to southern California in the U.S.A., which span distances from approximately hundreds of meters to 1450 km, while elevations range from near sea level to nearly 500 m. In addition, sensorial (i.e. aroma, taste, and mouthfeel) and chemical (i.e. polyphenolic and volatile) differences across the different vineyard sites have also been observed among these wines at two aging time points. While strong evidence exists to support that grapes grown in different regions can produce wines with unique chemical and sensorial profiles, even when a single clone is used, the understanding of growing site characteristics that result in this reproducible differentiation continues to emerge. One hypothesis is that the elemental profile that a vineyard site imparts to the grape berries and the resulting wine is an important contributor to this differentiation in chemistry and sensory of wines. For example, various classes of enzymes that catalyze the formation of key aroma compounds or their precursors require specific metals. In this work, we begin to report correlations between elemental and volatile aroma profiles of site-specific Pinot noir wines, made under standardized winemaking conditions, that have been previously shown to be distinguished separately by these chemical analyses.

Read More

Terroir and sustainability: an analysis of brazilian vineyards from a territorial perspective

In the concept of sustainable viticulture proposed by the OIV, it can be noted that enhancing terroir is also one measure of sustainability. Thus, the territorial approach may offer an interesting viewpoint from which to consider this issue in a multi-perspective way.

Read More

Climatic zoning of viticultural production periods over the year in the tropical zone: application of the methodology of the Géoviticulture MCC system

L’objectif de cette recherche est le zonage climatique des périodes viticoles de l’année dans la Vallée du São Francisco, région brésilienne productrice de vins située en climat tropical semi-aride. Dans cette région, la production peut être échelonnée sur tous les mois de l’année.

Read More

Study of the colour and phenolic evolution of three different tannin/anthocyanin ratios over time in a model wine

Phenolic compounds are important quality indicators in red wine. A large number of polyphenols play an important role in wine development, contributing to the colour and the sensory perception of the wines. Anthocyanins are the pigments responsible for the colour in young red wines while tannins are the principal contributors to the bitterness and the astringency of the wines. Wine polyphenols are considered more complex molecules than grape phenolics, due to the enormous number of chemical reactions which take place during the entire winemaking process and storage, forming more stable compounds.

Read More