OENO IVAS 2019 banner
IVES 9 IVES Conference Series 9 OENO IVAS 9 OENO IVAS 2019 9 Chemical and Biochemical reactions, including grape and wines microorganisms impact 9 Are dicysteinyl polysulfanes responsible for post-bottling release of hydrogen sulfide?

Are dicysteinyl polysulfanes responsible for post-bottling release of hydrogen sulfide?

Abstract

Hydrogen sulfide (H2S) has a significant impact on wine aroma attributes and wine quality when present at concentrations above its aroma threshold of 1.1 to 1.6 μg/L. Therefore, the management of H2S concentrations in wines, whether from fermentation or “other” origins, is an important consideration for winemakers. The main techniques used for H2S removal are oxidative handling and/or copper fining; however, the effectiveness of these treatments may be temporary, as H2S can often reappear post-bottling along with other volatile sulfur compounds (VSCs) when reductive conditions are re-established. Moreover, it is proposed that oxidative treatments applied in the presence of copper may produce compounds such as disulfides and diorganopolysulfanes, which might initially appear stable but are susceptible to reductive cleavage, thereby potentially acting as latent sources of H2S. 

The aim of this study was to determine whether putative polysulfanes could act as latent sources of H2S during post-bottling storage. Experiments conducted in model wine enabled identification of four dicysteinyl polysulfanes when H2S was oxidised in the presence of cysteine, copper and iron. The stability of the dicysteinyl polysulfanes formed in-situ was evaluated and conditions impacting the release of H2S from the polysulfanes were also determined, which provided some understanding of the possible mechanisms of release. 

The results of this study showed that the stability of the dicysteinyl polysulfanes decreased as sulfur chain length increased, which accorded with the relative proportions of polysulfanes initially formed. 

Notably, H2S was released over time, with the greatest decline in polysulfane relative abundance and largest release of H2S (up to 212 μg/L) being associated with the addition of commonly used reducing agents, especially sulfur dioxide, to the model wines containing the polysulfanes. Desulfurisation of cysteine could account for only minor quantities of H2S. In addition, Cysteine-S-sulfonates were tentatively identified by mass spectrometry after six months of storage, and similarly to the parent polysulfanes, their relative concentrations decreased with increasing number of linking sulfur atoms. These results shed light on the potential pathways for reformation of VSCs in bottled wine and demonstrate that dicysteinyl polysulfanes may have the potential to act as latent sources of H2S in wine post-bottling, potentially via a sulfitolysis mechanism.

DOI:

Publication date: June 11, 2020

Issue: OENO IVAS 2019

Type: Article

Authors

Marlize Bekker , David Jeffery, Gal Kreitman, John Danilewicz

The Australian Wine Research Institute PO Box 197 – Glen Osmond SA 5064 – Australia

Contact the author

Keywords

Polysulfanes, S-sulfonate, Copper, Sulfur dioxide 

Tags

IVES Conference Series | OENO IVAS 2019

Citation

Related articles…

Protein stabilization of white wines by stabilizing filtration: pilot studies

Protein stabilization is an important part of the winemaking process of white wines, and in this work we present the results of protein stabilization of different monovarietal wines (Xarel.lo, Chardonnay, and Muscat) by a continuous stabilizing filtration process using a column packed with zirconium oxide operating in a continuous regime in a closed loop at pilot scale.

Identification of cis-2-methyl-4-propyl-1,3-oxathiane as a new volatile sulfur compound (VSC) in wine

Despite their trace concentrations, volatile sulfur compounds (VSCs) are an important category of flavour-active compounds that significantly contribute to desirable or undesirable aromas of many foods and beverages. In wines, VSCs in the form of polyfunctional thiols, notably 3-sulfanylhexan-1-ol (3-SH), 3-sulfanylhexyl acetate (3-SHA), and 4-sulfanyl-4-methyl-pentan-2-one (4-MSP), possess extremely low olfactory thresholds (≈ ng/L) and pleasant “tropical aroma” notes. They have received much attention with respect to their sensory contributions, quantitative occurrences, biogenesis, and thiol management through viticulture and winemaking. However, the fate of these potent volatiles are still not fully understood.

Correlative study between degradation of rosé wine under accelerated conditions and under normal conditions

Several studies have tried to develop different methods to study the photodegradation of wine in an accelerated way, trying to elucidate the effect of light on the wine compounds[1]. In a previous study, our team developed a chamber that speeds up the photodegradation of rosé wine[2]. In the present work we have tried to establish a correlation between irradiation times in accelerated conditions and the natural exposure to the cycles of light that usually exist in markets or at home.

Assessing reserve nitrogen at dormancy for predicting spring nitrogen status in Chardonnay grapevines

Nitrogen (N) supply strongly influences vine productivity and berry composition, matching availability and uptake requirements of vines during the growing season is essential to optimize vine nutrition. The nutritional status of grapevines is commonly assessed by the determination of petiole nutrient concentrations at flowering. The reserve N could also be an earlier indicator for grapevine N status, this work aimed to assess how the petiole levels relate to these perennial N reserves.

Delaying grapevine budbreak and/or phenological stages

In the current climatic context, with milder winters leading to earlier budburst in most wine regions, vines are exposed to the risk of spring frosts for a longer period. Depending on the year, frost can lead to yield losses of between 20 and 100 %, jeopardizing the economic survival of wine estates. In addition, by destroying young shoots, spring frosts can impact the following season’s production, by reducing the number of canes available for pruning, for example. Late pruning is one method to combat spring frosts.