Ability of Exogenous or Wort Endogenous Enzymes to Release Free Thiols from Hop Cysteinylated and Glutathionylated <i>S</i>-Conjugates

Chenot, Cécile; Willemart, G; Gros, Jacques; Collin, Sonia

doi:10.1080/03610470.2021.2021766

Cited by 6 publications

(11 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Regardless, there are clear differences in individual yeast strains’ ability to release conjugated thiols from their precursors. This is likely influenced by medium conditions such as FAN and pH, as supported by recent publications by Chenot et al , …”

Section: Resultssupporting

confidence: 54%

“…Regardless, there are clear differences in individual yeast strains' ability to release conjugated thiols from their precursors. This is likely influenced by medium conditions such as FAN and pH, as supported by recent publications by Chenot et al 22,25 Regardless of the fermentation medium, there was an overall increase in free thiol content compared to their prefermentation value(s). This was expected as all strains used in experimentation (excluding LalBrew Farmhouse) had IRC7 F or heterozygous expression of IRC7 F and IRC7 S .…”

Section: Medium Conditions Potentially Influence Thiolmentioning

confidence: 61%

“…In contrast to CG3SH, GC3SH concentrations were higher postfermentation in both media, especially for the Lal-1 wine strain. There is some evidence that β-lyase may act on the dipeptides directly . Because GC3SH is a recently discovered thiol precursor in 3SH formation, it remains poorly understood in terms of its metabolic role .…”

Section: Resultsmentioning

confidence: 99%

“…There is overwhelming evidence that the IRC7 gene in yeast is responsible for encoding β-lyase, , although it is important to mention that other genes such as STR3 and CYS3 may also play a role in thiol release due to their ability to encode for β-lyase enzymes. , There are also several other factors such as nitrogen suppression and enzymatic breakdown of glutathionylated precursors that can influence the release of thiols . β-Lyase is an enzyme that has been shown to cleave conjugated cysteinylated thiol precursors to release 4MSP and 3SH, and it appears that it may be able to release cysteine–glutathione conjugates in hops when exogenous apotryptophanase is present . Published research into β-lyase’s influence on releasing 3SH is conflicting with research, noting a preference for 4MSP release. , While considerable research has been published on this topic in the wine arena, there is limited research regarding β-lyase activity and its role in free thiol release in beer.…”

Section: Introductionmentioning

confidence: 99%

“…21 β-Lyase is an enzyme that has been shown to cleave conjugated cysteinylated thiol precursors to release 4MSP and 3SH, and it appears that it may be able to release cysteine−glutathione conjugates in hops when exogenous apotryptophanase is present. 22 Published research into β-lyase's influence on releasing 3SH is conflicting with research, noting a preference for 4MSP release. 17,23 While considerable research has been published on this topic in the wine arena, there is limited research regarding β-lyase activity and its role in free thiol release in beer.…”

Section: ■ Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Examining How the Fermentation Medium Influences Thiol Expression and Its Perceived Aroma in Commercial Brewing Yeast Strains

Molitor

Fischborn

Dagan³

et al. 2023

J. Agric. Food Chem.

View full text Add to dashboard Cite

In Saccharomyces, the IRC7 gene encodes for a cysteine S-conjugate β-lyase enzyme which can release polyfunctional thiols from their cysteinylated precursor forms, thereby promoting thiol aroma in beer. This study examined the thiol production of 10 commercial yeast strains in two different media, a hopped yeast extract−peptone−dextrose (YPD) medium and a 100% barley malt wort to explore how differences in yeast strain and medium conditions influence the release of polyfunctional thiols. 3-Sulfanylhexan-1-ol was most affected by medium conditions, and its concentrations were highest in wort fermentations. The higher nitrogen content and pH of the YPD medium relative to the wort fermentations were notable differences, and significant correlations between these variables and the extent of free thiol production were observed. A strong association existed between polyfunctional thiol concentrations and the fermentation-derived, malt, and hop-derived compounds 2-phenylethanol, β-damascenone, and βionone. The sensory impressions of thiol character in beer were influenced by the presence of other aromatic compounds such as esters and terpene alcohols, and aroma attributes such as "tropical" were not the most suitable for describing beers brewed with yeasts that fully express homozygous IRC7 F . Sensory attributes "sweaty", "vegetal", and "overripe fruit" were more strongly associated with these strains.

show abstract

Section: Resultssupporting

confidence: 54%

Section: Medium Conditions Potentially Influence Thiolmentioning

confidence: 61%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Examining How the Fermentation Medium Influences Thiol Expression and Its Perceived Aroma in Commercial Brewing Yeast Strains

Molitor

Fischborn

Dagan³

et al. 2023

J. Agric. Food Chem.

View full text Add to dashboard Cite

show abstract

Fruits of their labour: biotransformation reactions of yeasts during brewery fermentation

Svedlund¹,

Evering²,

Gibson³

et al. 2022

Appl Microbiol Biotechnol

View full text Add to dashboard Cite

There is a growing appreciation for the role that yeast play in biotransformation of flavour compounds during beverage fermentations. This is particularly the case for brewing due to the continued popularity of aromatic beers produced via the dry-hopping process. Here, we review the current literature pertaining to biotransformation reactions mediated by fermentative yeasts. These reactions are diverse and include the liberation of thiols from cysteine or glutathione-bound adducts, as well as the release of glycosidically bound terpene alcohols. These changes serve generally to increase the fruit and floral aromas in beverages. This is particularly the case for the thiol compounds released via yeast β-lyase activity due to their low flavour thresholds. The role of yeast β-glucosidases in increasing terpene alcohols is less clear, at least with respect to fermentation of brewer’s wort. Yeast acetyl transferase and acetate esterase also have an impact on the quality and perceptibility of flavour compounds. Isomerization and reduction reactions, e.g. the conversion of geraniol (rose) to β-citronellol (citrus), also have potential to alter significantly flavour profiles. A greater understanding of biotransformation reactions is expected to not only facilitate greater control of beverage flavour profiles, but also to allow for more efficient exploitation of raw materials and thereby greater process sustainability. Key points • Yeast can alter and boost grape- and hop-derived flavour compounds in wine and beer • β-lyase activity can release fruit-flavoured thiols with low flavour thresholds • Floral and citrus-flavoured terpene alcohols can be released or interconverted

show abstract

Evidence of Enzymatic and Chemical Interconversions of Barley Malt 3-Sulfanylhexanol Conjugates during Mashing

Chenot,

Collin,

Suc

et al. 2023

J. Agric. Food Chem.

Self Cite

View full text Add to dashboard Cite

Recent studies have highlighted in malt the occurrence of the glutathionylated precursor of 3-sulfanylhexanol (G-3SHol) at concentrations reaching hundreds of μg/kg. Here, SIDA-LC-MS/MS was used to investigate the potential conversion of G-3SHol to its dipeptide and cysteinyl analogues during mashing. At 45 and 55 °C, malt γGT and carboxypeptidase activities quickly degrade G-3SHol (up to 90% loss), first to the cysteinylglycine conjugate and then to the cysteine conjugate (up to 205% increase). No γ-glutamylcysteine S-conjugate formation is observed. At 80 °C, despite enzyme inactivation, the G-3SHol level decreases steadily because of suspected imine formation with wort aldehydes at pH 5.5. More surprisingly, CysGly-3SHol is still generated at 80 °C. This indicates the presence in the wort of as yet unidentified precursors.

show abstract

Ability of Exogenous or Wort Endogenous Enzymes to Release Free Thiols from Hop Cysteinylated and Glutathionylated S-Conjugates

Cited by 6 publications

References 34 publications

Examining How the Fermentation Medium Influences Thiol Expression and Its Perceived Aroma in Commercial Brewing Yeast Strains

Examining How the Fermentation Medium Influences Thiol Expression and Its Perceived Aroma in Commercial Brewing Yeast Strains

Fruits of their labour: biotransformation reactions of yeasts during brewery fermentation

Evidence of Enzymatic and Chemical Interconversions of Barley Malt 3-Sulfanylhexanol Conjugates during Mashing

Contact Info

Product

Resources

About