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…

EFFECTS OF HYDROXYTYROSOL ON THE CHEMICAL PROFILE AND SENSORY ATTRIBUTES OF A RED TUSCAN WINE

The chemical profile and sensory attributes were studied in Borrigiano IGT Toscana wine (Italy), a blend of Sangiovese 85% and Cabernet Sauvignon 15% grapes harvested in September 2020, where 2-(3,4-dihydroxyphenyl)ethanol (hydroxytyrosol, HT, [1]) was added to a 750-ml wine bottle in 3 different amounts (30, 60, 120 mg) and compared with the control (no HT addition). The study aimed to evaluate whether Polyphenol-HT1®, a high purity HT (>99%) produced by Nova Mentis using biotechnology, could be used as a supplement to sulfites and how it would impact the sensory and chemical profile of this wine [2]. Each sample was prepared in triplicate.

Read More

HOW OXYGEN CONSUMPTION INFLUENCES RED WINES VOLTAMMETRIC PROFILE

Phenolic compounds play a central role in sensory characteristics of wine, such as colour, mouthfeel, flavour and determine its shelf life. Furthermore, the major non-enzymatic wine oxidation process is due to the catalytic oxidation of phenols in quinones. Due their importance, during the years have been developed different analytical methods to monitor the concentration of phenols in wine, such as Folin-Ciocalteu method, spectrophotometric techniques and HPLC. These methods can also be used to follow some oxidation-related chemical transformations.

Read More

DOES LIGNIN AN ACCEPTABLE MARKER OF GRAPESEED MATURATION AND QUALITY?

Usually the winemaker consider polyphenols from the grape berry as an actor of the wine quality. There are frequently consider as a marker of grape maturity. It is commonly known that winemaker consider tannins and anthocyanins as main polyphenol actors for winemaking practices and wine quality. Here we will focus on the characterisation of lignins in grape seeds. Previous studies suggest that the seed is lignified [1], which could explain the change in colour of the seed when it reaches maturity and thus provide a reliable indicator for describing the maturity stage in the seed.

Read More

RED WINE AGING THROUGH 1H-NMR METABOLOMICS

Premium red wines are often aged in oak barrel. This widespread winemaking process is used, among others, to provide roundness and complexity to the wine. The study of wine evolution during barrel aging is crucial to better ensure control of wine quality.
¹H-NMR has already been proved to be an efficient tool to monitor winemaking process [1]. Indeed, it is a non-destructive technique, it requires a small amount of sample and a short time of analysis, yet it provides clues about several chemical families.

Read More

INCREASING PINOT NOIR COLOUR DENSITY THROUGH SEQUENTIAL INOCULATION OF FLOCCULENT COMMERCIAL WINE YEAST SPECIES

Vitis vinifera L. cv. Pinot noir can be challenging to manage in the winery as its thin skins require careful handling to ensure sufficient extraction of wine colour to promote colour stability during ageing.1 Literature has shown that fermentation with flocculent yeasts can increase red wine colour density.2 As consumers prefer greater colour density in red wines,3 the development of tools to increase colour density would be useful for the wine industry. This research explored the impact of interspecies sequential inoculation and co-flocculation of commercial yeast on Pinot noir wine colour.

Read More