Role of Elemental Sulfur in Forming Latent Precursors of H<sub>2</sub>S in Wine

Jastrzembski, Jillian A.; Allison, Rachel B.; Friedberg, Elle; Sacks, Gavin L.

doi:10.1021/acs.jafc.7b04015

Cited by 39 publications

(40 citation statements)

References 31 publications

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“…react to something (we claim polythionates) in some wine. (5) The increments of free H 2 S observed when wine is stored in anoxia are mostly the release of complexed forms: This is valid for polythionates and other components of the "Wackenroder solution", if considered as part of the "complexed forms" [29]. (6) Analytical methods to detect H 2 S, MeSH and other VSCs in the headspace do not work, if they suffer interactions in wines occasionally so strong that in some wines, they are not released to the wine headspace.…”

Section: Discussion Of Polydithionates: the Answer To Some Unsolved Qmentioning

confidence: 97%

“…addition [29]. The identity of these intermediates was unclear, but could potentially involve polysulfide (polythionates) adducts.…”

Section: Discussion Of Polydithionates: the Answer To Some Unsolved Qmentioning

confidence: 99%

“…Still other latent sources of H 2 S and MeSH may exist, like the potential contribution of non-volatile asymmetric disulfides, trisulfides or even polysulfanes (e.g., adducts with other thiol compounds), which have not been well explored. Since the natural tripeptide glutathione [75,76] represents the thiol with the highest concentration in must and wine (up to 120 mg), this sulfanyl compound is strongly involved in these processes of reductive off-odor formation [16,29]. This topic would need its own section.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, a polythionate (tetrathionate) was detected in wine [29]. Although this appearance is a first proof for speculations that organopolysulfanes and polysulfides could undergo two sulfitolysis steps to form polythionates, the reason why higher polythionates could not be detected remains unclear.…”

Section: Polythionates In Wine As Precursorsmentioning

confidence: 99%

“…During fermentation, yeast produces H 2 S in order to fulfil the need for the sulfur-containing amino acids methionine and cysteine via the sulfate assimilation pathway, simulating the original conditions for the formation of the "WS", containing polysulfanmono and disulfonic acids (polythionates). The experiments cited in [29] ran with 50 mg potassium bisulfite K 2 S 2 O 5 (which equals 33.3 mg SO 2 ) and 0-100 mg addition of elemental sulfur. In these experiments, up to 50 µg of total H 2 S was formed (most in TECP = triscarboxyethyl phosphine releasable form), which is far over its odor threshold of 1 µg L −1 .…”

Section: The Role Of Coppermentioning

confidence: 99%

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Recent Developments on the Origin and Nature of Reductive Sulfurous Off-Odours in Wine

Müller¹,

Rauhut

2018

Fermentation

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Reductive sulfurous off-odors are still one of the main reasons for rejecting wines by consumers. In 2008 at the International Wine Challenge in London, approximately 6% of the more than 10,000 wines presented were described as faulty. Twenty-eight percent were described as faulty because they presented “reduced characters” similar to those presented by “cork taint” and in nearly the same portion. Reductive off-odors are caused by low volatile sulfurous compounds. Their origin may be traced back to the metabolism of the microorganisms (yeasts and lactic acid bacteria) involved in the fermentation steps during wine making, often followed by chemical conversions. The main source of volatile sulfur compounds (VSCs) are precursors from the sulfate assimilation pathway (SAP, sometimes named as the “sulfate reduction pathway” SRP), used by yeast to assimilate sulfur from the environment and incorporate it into the essential sulfur-containing amino acids methionine and cysteine. Reductive off-odors became of increasing interest within the last few years, and the method to remove them by treatment with copper (II) salts (sulfate or citrate) is more and more questioned: The effectiveness is doubted, and after prolonged bottle storage, they reappear quite often. Numerous reports within the last few years and an ongoing flood of publications dealing with this matter reflect the importance of this problem. In a recent detailed review, almost all relevant aspects were discussed on a scientific data basis, and a “decision tree” was formulated to support winemakers handling this problem. Since we are dealing with a very complicated matter with a multitude of black spots still remaining, these advices can only be realized using specific equipment and special chemicals, not necessarily found in small wineries. The main problem in dealing with sulfurous compounds arises from the high variability of their reactivities. Sulfur is a metalloid with a large valence span across eight electron transformations from S (−II) up to S (+VI). This allows it to participate in an array of oxidation, reduction and disproportionation reactions, both abiotic and linked to microbial metabolism. In addition, sulfur is the element with the most allotropes and a high tendency to form chains and rings, with different stabilities of defined species and a high interconvertibility among each other. We suppose, there is simply a lack of knowledge of what is transferred during filling into bottles after fermentation and fining procedures. The treatment with copper (II) salts to remove sulfurous off-odors before filling rather increases instead of solving the problem. This paper picks up the abundant knowledge from recent literature and tries to add some aspects and observations, based on the assumption that the formation of polythionates, hitherto not taken into consideration, may explain some of the mystery of the re-appearance of reductive off-odors.

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Section: Discussion Of Polydithionates: the Answer To Some Unsolved Qmentioning

confidence: 97%

“…addition [29]. The identity of these intermediates was unclear, but could potentially involve polysulfide (polythionates) adducts.…”

Section: Discussion Of Polydithionates: the Answer To Some Unsolved Qmentioning

confidence: 99%