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…

Effect of the commercial inoculum of arbuscular mycorrhiza in the establishment of a commercial vineyard of the cultivar “Manto negro

The favorable effect of symbiosis with arbuscular mycorrhizal fungi (AMF) has been known and studied since the 60s. Nowadays, many companies took the chance to start promoting and selling commercial inoculants of AMF, in order to be used as biofertilizers and encourage sustainable biological agriculture. However, the positive effect of these commercial biofertilizers on plant growth is not always demonstrated, especially under field conditions. In this study, we used a commercial inoculum on newly planted grapevines of a local cultivar grafted on a common rootstock R110. We followed the physiological status of vines, growth and productivity and functional biodiversity of soil bacteria during the first and second years of 20 inoculated with commercial inoculum bases on Rhizophagus irregularis and Funeliformis mosseaeAMF at field planting time and 20 non-inoculated control plants. All the parameters measured showed a neutral to negative effect on plant growth and production. The inoculated plants always presented lower values of photosynthesis, growth and grape production, although in some cases the differences did not reach statistical significance. On the contrary, the inoculation supposed an increase of the bacterial functional diversity, although the differences were not statistically significant either. Several studies show that the effect of inoculation with AMF is context-dependent. The non-favorable effects are probably due to inoculation ineffectiveness under complex field conditions and/or that, under certain conditions, AMF presence may be a parasitic association. This puts into question the effectiveness of its application in the field. Therefore, it is recommended to only resort to this type of biofertilizer when the cultivation conditions require it (e.g., very low previous microbial diversity, foreseeable stress due to drought, salinity, or lack of nutrients) and not as a general fertilization practice.

Emosensory profile and chemical characterization of wine vinegar from the Douro and Rioja demarcated regions

Wine vinegars have a tangy flavor and are versatile in cooking. They’ve been used since the neolithic period and are now used as microbial inhibitors and acidifiers. They’re low in calories, have antioxidants, and have a long shelf life, but quality may decrease after opening. The objective of this study focuses on the physical-chemical, sensory, and emotional characterization of wine vinegar samples from the douro demarcated region and la rioja. In total, 22 samples of wine vinegar were analyzed at the time of opening.

Terroir effects on the response of Tempranillo grapevines to irrigation in four locations of Spain: grape and must composition

This work discusses the effects of soil and weather conditions on the grape composition of cv. Tempranillo in four different locations of Spain, during the 2008-2011 seasons.

Characterization of bunch compactness and identification of associated genes in a diverse collection of cultivars of Vitis vinifera L.

Compactness is a complex trait of V. vinifera L. and is defined ultimately by the portion of free space within the bunch which is not occupied by the berries. A high degree of compactness results in poor ventilation and consequently a higher susceptibility to fungal diseases, diminishing the quality of the fruit. The easiness to conceptualize the trait and its importance arguably contrasts with the difficulty to measure and quantify it. However, recent technical advancements have allowed to study this attribute more accurately over the last decade. Our main objective was to explore the underlying genetics determining bunch compactness by applying updated phenotyping methods in a collection of V. vinifera L. cultivars with a wide genetic diversity.

Foam characteristics of white, rosé and red sparkling wines elaborated by the champenoise method

Contribution Foam is the characteristic that differentiates sparkling wines from still wines, being the first sensory attribute that tasters and consumers perceive and that determines the final quality of sparkling wines [1]. The foaming properties mainly depend on the chemical composition of wines [2-3], and different factors involved in wine composition will have an effect on foam quality. In Spain, the sparkling wine market focuses on the production of white and rosé sparkling wine, with very low production of red sparkling wines. However, this type of wines is elaborated in countries like Australia, South-Africa, Argentina, Italy or Portugal, with a great acceptance by consumers. No studies on the foaming characteristics of red sparkling wines have been found.