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…

DISCRIMINATION OF BOTRYTIS CINEREA INFECTED GRAPES USING UNTARGE-TED METABOLOMIC ANALYSIS WITH DIRECT ELECTROSPRAY IONISATION MASS SPECTROMETRY

Infection of grapes (Vitis vinifera) by Botrytis cinerea (grey mould) is a frequent occurrence in vineyards and during prolonged wet and humid conditions can lead to significant detrimental impact on yield and overall quality. Growth of B. cinerea causes oxidisation of phenolic compounds resulting in a loss of colour and formation of a suite of off-flavours and odours in wine made from excessively infected fruit. Apart from wine grapes, developing post-harvest B. cinerea infection in high-value horticultural products during storage, shipment and marketing may cause significant loss in fresh fruits, vegetables and other crops. A rapid and sensitive assessment method to detect, screen and quantify fungal infection would greatly assist viticultural growers and winemakers in determining fruit quality.

Read More

EXPLORING THE ROLE OF TRANSITION METAL IONS IN THE EVOLUTION OF ESTERS COMPOSITION OF YOUNG WHITE WINE DURING AGEING

Young white wines are typically released to the market a few months after harvest, to be consumed within a year, when their fresh fruity aromas are still dominant and appealing to modern consumers. Esters, particularly higher alcohol acetates (HAAs) and ethyl esters of fatty acids (EEFAs), play a central role in the fruity expression of young white wines [1]. However, these esters are known to undergo significant hydrolysis during the first months of aging [1, 2].

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

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

CONVOLUTIONAL NEURAL NETWORK TO PREDICT GENETIC GROUP AND SULFUR TOLERANCE OF BRETTANOMYCES BRUXELLENSIS

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.20.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...
Read More