The level of hydrogen sulfide (HS) can increase during abiotic storage of wines, and potential latent sources of HS are still under investigation. We demonstrate that elemental sulfur (S) residues on grapes not only can produce HS during fermentation but also can form precursors capable of generating additional HS after bottle storage for 3 months. HS could be released from S-derived precursors by addition of a reducing agent (TCEP), but not by addition of strong brine to induce release of HS from metal sulfide complexes. The size of the TCEP-releasable pool varied among yeast strains. Using the TCEP assay, multiple polar S-derived precursors were detected following normal-phase preparative chromatography. Using reversed-phase liquid chromatography and high-resolution mass spectrometry, we detected an increase in the levels of diglutathione trisulfane (GSSSG) and glutathione disulfide (GSSG) in S-fermented red wine and an increase in the levels of glutathione S-sulfonate (GSSO) and tetrathionate (SO) in S-fermented white wine as compared to controls. GSSSG, but not SO, was shown to evolve HS in the presence of TCEP. Pathways for the formation of GSSSG, GSSG, GSSO, and SO from S are proposed.

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Hydrogen sulfide (H2S, "rotten egg" aroma) concerns winemakers due to its contribution to sulfur-like off-aromas (SLOs). However, there are a lack of inexpensive, convenient methods for quantitation of H2S in wines at or below its reported odor threshold. The use of selective, colorimetric gas detection tubes (GDT) for measurement of H2S during fermentation has been previously described, but this approach has not been adapted and validated for finished wines.We developed and validated protocols for rapid, inexpensive analysis of H2S using GDTs and ASEV CATALYST REPORT

Copper−sulfhydryl complexes in wine can be disrupted by addition of brine to release free hydrogen sulfide (H 2 S), and the resulting "brine-releasable H 2 S" is reported to correlate with formation of H 2 S during bottle storage. However, both the mechanism of the brine-release assay and factors affecting the stability of copper sulfhydryls under brine-release conditions are not well understood. By varying brine composition and concentration, it is shown that release of copper-complexed H 2 S requires the presence of a halide (Cl − and Br − ) and is not due to a general "salting-out" effect. Release of copper-complexed H 2 S by the brine dilution assay is highly temperature-dependent. When H 2 S and Cu(II) are added to a model wine, brine-releasable H 2 S decreases markedly (∼10-fold) after a 20 min incubation period prior to performing the brine-release assay. In commercial wines, the fraction of added H 2 S recovered through the brine-release assay was correlated with the initial glutathione (GSH) concentration (r 2 = 0.58) but not with initial Cu. Negligible additional release of H 2 S from organopolysulfanes was observed following addition of a disulfidereducing agent (tris(2-carboxyethyl)phosphine). As previous studies have reported a correlation between H 2 S formed under brinerelease conditions and normal storage, these results suggest that the susceptibility of a wine to form latent copper−sulfhydryl precursors of H 2 S following copper addition is dependent on the concentration of sulfhydryls like GSH.

Background and goals. Wines in aluminum beverage cans ("canned wines") are a rapidly growing packaging segment due to several factors, including convenience and sustainability advantages. However, canned wines have higher concentrations of hydrogen sulfide (H2S; "rotten egg") than wines in glass packaging. It was hypothesized that wine composition and liner selection affect H2S formation in canned wines.Methods and key findings. Commercial wines (n=10) were stored in either glass or aluminum beverage cans with one of three liners for up to 32 weeks. Wines stored in glass showed AJEV Papers in Press.