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Hydrogen sulfide: Difference between revisions
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Maximum amounts of sulfide are liberated when the depletion of nitrogen occurs during the exponential growth phase. Conversely, when depletion of nitrogen occurs during the stationary phase, sulfide liberation is a lower amount and is short-lived.<ref name="Jiranek"/> (See [[Yeast]] for more about growth phases.) | Maximum amounts of sulfide are liberated when the depletion of nitrogen occurs during the exponential growth phase. Conversely, when depletion of nitrogen occurs during the stationary phase, sulfide liberation is a lower amount and is short-lived.<ref name="Jiranek"/> (See [[Yeast]] for more about growth phases.) | ||
While sulfide formation occurs mainly during [[primary fermentation]], additional VSCs can be formed at later stages of production, particularly in wine.<ref name="Muller"/> This phenomenon is rarely a problem in beer production. VSC formation in wine can be difficult to predict and is not necessarily related to sulfide issues during the primary fermentation.<ref name="Osborne"/> The VSCs involved include [[mercaptans]] (AKA thiols or mono-sulfides or higher sulfides) and [[disulfides]] that have distinctive aromas such as skunky, rubbery, garlic, onion, or cabbage-like.<ref name="Osborne"/><ref name="Huang"/><ref>[https://www.etslabs.com/library/31 Volatile sulfides: detection and prevention.] ETS Laboratories. Accessed March 2020.</ref> These compounds result from degradation of sulfur-containing compounds in the yeast [[lees]], and chemically-bound sulfide may be released during aging or storage.<ref name="Osborne"/><ref name="Rauhut"/><ref name="Jastrzembski">Jastrzembski J, Sacks G. [https://grapesandwine.cals.cornell.edu/sites/grapesandwine.cals.cornell.edu/files/shared/Research%20Focus%202016-3a.pdf Sulfur residues and post-bottling formation of hydrogen sulfide.] Research News from Cornell's Viticulture and Enology Program Research Focus. 2016;3a.</ref> Sulfide formation has also been reported to occur in the bottle when naturally bottle carbonating with yeast.<ref>[https://www.homebrewtalk.com/forum/threads/preventing-sulfide-when-bottle-conditioning.665501/ Preventing sulfide when bottle conditioning.] HomebrewTalk forum. Published 2019. Accessed July 2020.</ref><ref>[https://www.homebrewtalk.com/forum/threads/sulfur-after-bottling-what-can-be-done.677439/ "Sulfur after bottling...what can be done?"] HomebrewTalk forum. Published 2020. Accessed July 2020.</ref> Even VSCs that had apparently been removed may reappear if conditions in wine become more [[reductive]] (e.g. during barrel aging or in the bottle).<ref name="Elusive"/><ref name="Vela">Vela E, Hernandez-Orte P, Franco-Luesma E, Ferreira V. [https://www.sciencedirect.com/science/article/pii/S0308814617315984 Micro-oxygenation does not eliminate hydrogen sulfide and mercaptans from wine; it simply shifts redox and complex-related equilibria to reversible oxidized species and complexed forms.] ''Food Chem.'' 2018;243:222–230.</ref> | While sulfide formation occurs mainly during [[primary fermentation]], additional VSCs can be formed at later stages of production, particularly in wine.<ref name="Muller"/> This phenomenon is rarely a problem in beer production. VSC formation in wine can be difficult to predict and is not necessarily related to sulfide issues during the primary fermentation.<ref name="Osborne"/> The VSCs involved include [[mercaptans]] (AKA thiols or mono-sulfides or higher sulfides) and [[disulfides]] that have distinctive aromas such as skunky, rubbery, garlic, onion, or cabbage-like.<ref name="Osborne"/><ref name="Huang"/><ref>[https://www.etslabs.com/library/31 Volatile sulfides: detection and prevention.] ETS Laboratories. Accessed March 2020.</ref> These compounds result from degradation of sulfur-containing compounds in the yeast [[lees]], and chemically-bound sulfide may be released during aging or storage.<ref name="Osborne"/><ref name="Rauhut"/><ref name="Jastrzembski">Jastrzembski J, Sacks G. [https://grapesandwine.cals.cornell.edu/sites/grapesandwine.cals.cornell.edu/files/shared/Research%20Focus%202016-3a.pdf Sulfur residues and post-bottling formation of hydrogen sulfide.] Research News from Cornell's Viticulture and Enology Program Research Focus. 2016;3a.</ref> Sulfide formation has also been reported to occur in the bottle when naturally bottle carbonating with yeast.<ref>[https://www.homebrewtalk.com/forum/threads/preventing-sulfide-when-bottle-conditioning.665501/ Preventing sulfide when bottle conditioning.] HomebrewTalk forum. Published 2019. Accessed July 2020.</ref><ref>[https://www.homebrewtalk.com/forum/threads/sulfur-after-bottling-what-can-be-done.677439/ "Sulfur after bottling...what can be done?"] HomebrewTalk forum. Published 2020. Accessed July 2020.</ref> Even VSCs that had apparently been removed may reappear if conditions in wine become more [[reductive aroma|reductive]] (e.g. during barrel aging or in the bottle).<ref name="Elusive"/><ref name="Vela">Vela E, Hernandez-Orte P, Franco-Luesma E, Ferreira V. [https://www.sciencedirect.com/science/article/pii/S0308814617315984 Micro-oxygenation does not eliminate hydrogen sulfide and mercaptans from wine; it simply shifts redox and complex-related equilibria to reversible oxidized species and complexed forms.] ''Food Chem.'' 2018;243:222–230.</ref> | ||
There is not always correlation between total sulfide produced by yeast during fermentation and the sulfide concentration in the final wine/beer/etc.<ref name="UglianoM">Ugliano M, Fedrizzi B, Siebert T, et al. [https://pubs.acs.org/doi/abs/10.1021/jf8037693 Effect of nitrogen supplementation and ''Saccharomyces'' species on hydrogen sulfide and other volatile sulfur compounds in shiraz fermentation and wine.] ''J Agric Food Chem.'' 2009;57(11):4948–4955.</ref><ref name="Ugliano"/> | There is not always correlation between total sulfide produced by yeast during fermentation and the sulfide concentration in the final wine/beer/etc.<ref name="UglianoM">Ugliano M, Fedrizzi B, Siebert T, et al. [https://pubs.acs.org/doi/abs/10.1021/jf8037693 Effect of nitrogen supplementation and ''Saccharomyces'' species on hydrogen sulfide and other volatile sulfur compounds in shiraz fermentation and wine.] ''J Agric Food Chem.'' 2009;57(11):4948–4955.</ref><ref name="Ugliano"/> | ||