terclim by ICS banner
IVES 9 IVES Conference Series 9 ANALYZING THE ROLE OF ELEMENTAL SULFUR IN GRAPE JUICE ON THE DEVELOPMENT OF POLYFUNCTIONAL MERCAPTANS IN SAUVIGNON BLANC WINES

ANALYZING THE ROLE OF ELEMENTAL SULFUR IN GRAPE JUICE ON THE DEVELOPMENT OF POLYFUNCTIONAL MERCAPTANS IN SAUVIGNON BLANC WINES

Abstract

Sauvignon blanc is characterized by distinctive aromas, both fruity and herbaceous. The “green” cha- racter has been attributed to the methoxypyrazines, while the “fruity” character is associated with polyfunctional mercaptans . Polyfunctional mercaptans are of great significance due to their high impact on wines and associated low perception thresholds.

Elemental sulfur (S⁰) is widely used to protect grapevines from powdery mildew. Machine harvesting can enhance the formation of C6-compounds from grape lipids, leading to desirable polyfunctional mer- captan formation in wines.

A missing piece of information in most past studies on the formation of polyfunctional thiols has been the concentration of elemental sulfur in grapes. In this research, we aimed first to develop an easy and applicable method for a winery setting to analyse elemental sulfur concentration in grape juice samples. With this method in place, trials were then established to examine the link between elemental sulfur in the juice and 3MH/3MHA formation in wines. The trials were undertaken during three consecutive harvests in New Zealand in 2020, 2021, and 2022.

The study developed a sulfide sensor to measure elemental sulfur levels in grape juice samples and in- vestigated the correlation between S⁰ and polyfunctional mercaptan concentration in resulting wines. We reduced S⁰ to sulfide using dithiothreitol in acidic conditions and used an ion-selective electrode to measure sulfide concentrations. GC-MS was used to compare thiol concentration in wine with juice S⁰ levels from 2020 and 2021 samples. The investigation was expanded in 2022 by manually applying S⁰ to grapes at various intervals prior to harvesting and analyzing the relationship between residual S⁰ levels in juice and polyfunctional mercaptans in resulting wines.

The study established a dependable method based on ion-selective analysis and produced accurate ca- libration curves. The reduction process was found to be effective and the apparatus performed well with both standard and juice samples. Additionally, the results from the 2020 and 2021 trials revealed a cor- relation between increased juice elemental sulfur and a higher formation of 3MH/3MHA, supporting the theory that S⁰ contributes to the formation of 3MH in wine. This correlation was further confirmed in the 2022 trial, which saw a substantial increase in 3MH/3MHA in wines resulting from the manual application of S⁰ to the grapes through late spraying in the field.

 

1. Lund, C. M.; Thompson, M. K.; Benkwitz, F.; Wohler, M. W.; Triggs, C. M.; Gardner, R.; Heymann, H.; Nicolau, L. American Jour-nal of Enology and Viticulture 2009, 60, 1.
2. Harsch, M. J.; Benkwitz, F.; Frost, A.; Colonna-Ceccaldi, B.; Gardner, R. C.; Salmon, J.-M. Journal of agricultural and food che-mistry 2013, 61, 3703-3713.
3. Kwasniewski, M.T.; Sacks, G.L.; Wilcox, W.F. J. Enol. Vitic. 2014, 65, 453-462.
4. Lyu, X.; Dias Araujo, L.; Quek, S.-Y.; Kilmartin, P. A. Food Chemistry 2021, 346, 128914.
5. Araujo, L. D.; Vannevel, S.; Buica, A.; Callerot, S.; Fedrizzi, B.; Kilmartin, P. A.; du Toit, W. J. Food Research International 2017, 98, 79-86.

DOI:

Publication date: February 9, 2024

Issue: OENO Macrowine 2023

Type: Article

Authors

Bahareh Sarmadi¹, Paul A. Kilmartin¹, Leandro D. Araújo ², Brandt P. Bastow¹

1. School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
2. Department of Wine, Food and Molecular Biosciences, Lincoln University, Lincoln, New Zealand 

Contact the author*

Keywords

Sauvignon blanc, polyfunctional mercaptans, elemental sulfur, varietal thiols

Tags

IVES Conference Series | oeno macrowine 2023 | oeno-macrowine

Citation

Related articles…

WHICH IMPACT FOR PROANTHOCYANIDIC TANNINS ON RED WINE FRUITY AROMA? SENSORY AND PHYSICOCHEMICAL APPROACHES

Previous research on the fruity character of red wines highlighted the role of esters. Literature provides evidence that, besides these esters, other compounds that are not necessarily volatiles may have an important impact on the overall aroma of wine, contributing to a modulation of its global aromatic expression. The goal of this work was to assess the olfactory consequences of a mixture between esters and proanthocyanidic tannins, through sensory and physico-chemical approaches.
Sensory analysis of numerous aromatic reconstitutions, including triangular tests, detection thresholds, and sensory profiles, were conducted in order to evaluate the sensory impact of tannins on red wine esters perception.

Read More

PRODUCTION OF A FUNCTIONAL BEVERAGE FROM WINEMAKING BY-PRODUCTS: A NEW WAY OF VALORISATION

In the challenge of transforming waste into useful products that can be re-used in a circular economy perspective, winery by-products can be considered as a source of potentially bioactive molecules such as polyphenols. The wine industry generates each year 20 million tons of by-products. Kombucha fermentation is an ancestral process which allow to increase the biological properties of tea by the action of a microbial consortium formed by yeasts and bacteria called SCOBY. It belongs to the field of healthy food for which the interest of consumers is growing. The objective of this work was to propose a new functional beverage made from winemaking by-products fermented by a Kombucha SCOBY.

Read More

OENOLOGICAL AND SUSTAINABILITY POTENTIAL OF WINES PRODUCED FROM DISEASE RESISTANT GRAPE CULTIVARS (PIWI WINES)

The strategy for sustainability in the wine sector of the EU refers to a set of practices and principles that aim to minimize the negative impact of wine production on the environment, social and economic sustainability. Sustainable wine production involves a range of practices that are designed to reduce waste, conserve resources, and promote the well-being of workers and communities.

Read More

THE ROLE OF CELL WALL POLYSACCHARIDES IN THE EXTRACTION OF ANTHOCYANINS AND TANNINS: RESULTS, PERSPECTIVES OF A MORE POSITIVE CONTRIBUTION

The composition of grape berry cell walls was studied on two grape varieties, two years and two maturation levels at the same time as the extraction of anthocyanins and tannins. The chemical composition of skins, seeds, and pulps, focused on polyphenols and polysaccharides, was compared to the chemical composition in polyphenols after extraction from the skins in model solutions or after wine making of the berries. Polyphenols were mainly characterized by UPLC-MS and HPLC-SEC. Polysaccharides were characterized by analysis of the neutral sugar compositions, and also by the CoMPP (comprehensive micropolymer profiling) analysis, a new method which targets the functional groups of cell wall polysaccharides.

Read More

PREVALENCE OF OAK-RELATED AROMA COMPOUNDS IN PREMIUM WINES

Barrel fermentation and barrel-ageing of wine are commonly utilised practices in premium wine production. The wine aroma compounds related to barrel contact are varied and can enhance a range of wine aromas and flavours, such as ‘struck flint’, ‘caramel’, ‘red berry’, ‘toasty’ and ‘nutty’, as well as conventional oaky characters such as ‘vanilla’, ‘spice’, ‘smoky’ and ‘coconut’. A survey of commercially produced premium Shiraz, Cabernet Sauvignon, Pinot Noir and Chardonnay wines was conducted, assessing the prevalence of compounds that have been proposed as barrel-ageing markers¹ including oak lactones, volatile phenols, furanones, aldehydes, thiazoles2,3, phenylmethanethiol⁴ and 2-furylmethanethiol.⁵

Read More