Analysis of Hop-Derived Thiols in Beer Using On-Fiber Derivatization in Combination with HS-SPME and GC-MS/MS

Dennenlöhr, Johanna; Thörner, Sarah; Rettberg, Nils

doi:10.1021/acs.jafc.0c06305

Cited by 22 publications

(28 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Resulting PFBBr-thioesters are then separated and analysed using gas chromatography tandem mass spectrometry (GC-MS/MS). The instrumental setup, parameters of sample preparation, GC-MS/MS analysis, calibration, and quantification were in full accordance to Dennenlöhr et al (2020). Each sample was analysed in duplicate.…”

Section: Beer Chemical Analysismentioning

confidence: 99%

Efficient breeding of industrial brewing yeast strains using CRISPR/Cas9-aided mating-type switching

Krogerus

Fletcher²,

Rettberg

et al. 2021

Appl Microbiol Biotechnol

Self Cite

View full text Add to dashboard Cite

Yeast breeding is a powerful tool for developing and improving brewing yeast in a number of industry-relevant respects. However, breeding of industrial brewing yeast can be challenging, as strains are typically sterile and have large complex genomes. To facilitate breeding, we used the CRISPR/Cas9 system to generate double-stranded breaks in the MAT locus, generating transformants with a single specified mating type. The single mating type remained stable even after loss of the Cas9 plasmid, despite the strains being homothallic, and these strains could be readily mated with other brewing yeast transformants of opposite mating type. As a proof of concept, we applied this technology to generate yeast hybrids with an aim to increase β-lyase activity for fermentation of beer with enhanced hop flavour. First, a genetic and phenotypic pre-screening of 38 strains was carried out in order to identify potential parent strains with high β-lyase activity. Mating-competent transformants of eight parent strains were generated, and these were used to generate over 60 hybrids that were screened for β-lyase activity. Selected phenolic off-flavour positive (POF +) hybrids were further sporulated to generate meiotic segregants with high β-lyase activity, efficient wort fermentation, and lack of POF, all traits that are desirable in strains for the fermentation of modern hop-forward beers. Our study demonstrates the power of combining the CRISPR/Cas9 system with classic yeast breeding to facilitate development and diversification of brewing yeast. Key points • CRISPR/Cas9-based mating-type switching was applied to industrial yeast strains. • Transformed strains could be readily mated to form intraspecific hybrids. • Hybrids exhibited heterosis for a number of brewing-relevant traits.

show abstract

Section: Beer Chemical Analysismentioning

confidence: 99%

Efficient breeding of industrial brewing yeast strains using CRISPR/Cas9-aided mating-type switching

Krogerus

Fletcher²,

Rettberg

et al. 2021

Appl Microbiol Biotechnol

Self Cite

View full text Add to dashboard Cite

show abstract

“…Here, we aimed specifically at enhancing the β-lyase of selected brewing yeast strains. Volatile thiols have a central role in contributing fruity hop aroma in beer, and they typically are abundant in modern heavily-hopped IPA-style beers (Gros et al 2012;Cibaka et al 2017;Dennenlöhr et al 2020;Bonnaffoux et al 2021). As the vast majority of all thiols in hops are cysteine-or glutathioneconjugated, and therefore odorless, there exists a large potential pool of aroma that can be freed from β-lyase activity, such as by Irc7p (Roncoroni et al 2011;Roland et al 2016).…”

Section: Discussionmentioning

confidence: 99%

“…The volatile thiols 4-mercapto-4-methyl-2-pentanone (4MMP), 3-mercapto-1-hexanol (3MH), and 3mercaptohexylacetate (3MHA) were determined using the method described by Dennenlöhr et al (2020). In this method thiols are extracted and derivatized by headspace solid-phase microextraction (HS-SPME) with on-fiber derivatization (OFD) using 2,3,4,5,6-pentafluorobenzyl bromide (PFBBr).…”

Section: Beer Chemical Analysismentioning

confidence: 99%

See 1 more Smart Citation

Efficient breeding of industrial brewing yeast strains using CRISPR/Cas9-aided mating-type switching

Krogerus

Fletcher²,

Rettberg

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Yeast breeding is a powerful tool for developing and improving brewing yeast in a number of industry-relevant respects. However, breeding of industrial brewing yeast can be challenging, as strains are typically sterile and have large complex genomes. To facilitate breeding, we used the CRISPR/Cas9 system to generate double-stranded breaks in the MAT locus, generating transformants with a single specified mating type. The single mating type remained stable even after loss of the Cas9 plasmid, despite the strains being homothallic, and these strains could be readily mated with other brewing yeast transformants of opposite mating type. As a proof of concept, we applied this technology to generate yeast hybrids with an aim to increase beta-lyase activity for fermentation of beer with enhanced hop flavour. First, a genetic and phenotypic pre-screening of 38 strains was carried out in order to identify potential parent strains with high beta-lyase activity. Mating-competent transformants of eight parent strains were generated, and these were used to generate over 60 hybrids that were screened for beta-lyase activity. Selected phenolic off-flavour positive (POF+) hybrids were further sporulated to generate meiotic segregants with high beta-lyase activity, efficient wort fermentation and lack of POF; all traits that are desirable in strains for the fermentation of modern hop-forward beers. Our study demonstrates the power of combining the CRISPR/Cas9 system with classic yeast breeding to facilitate development and diversification of brewing yeast.

show abstract

“…The second method covered the thioesters and sulfides, namely, S-methyl thioacetate, ethyl thioacetate, carbon disulfide, diethyl sulfide, dimethyl disulfide, and dimethyl trisulfide. Sample preparation for the analyses of volatile thiols was done using the on-fiber derivatization (OFD) assay as published by Dennenlöhr et al (2020b). The conditions during sample preparation and the GC separation were also as previously published.…”

Section: Determination Of Volatile Sulfur Componentsmentioning

confidence: 99%

Tradition as a Stepping Stone for a Microbial Defined Water Kefir Fermentation Process: Insights in Cell Growth, Bioflavoring, and Sensory Perception

et al. 2021

Self Cite

View full text Add to dashboard Cite

A process development from a traditional grain-based fermentation to a defined water kefir fermentation using a co-culture of one lactic acid bacterium and one yeast was elaborated as a prerequisite for an industrially scalable, controllable, and reproducible process. Further, to meet a healthy lifestyle, a low ethanol-containing product was aimed for. Five microbial strains—Hanseniaspora valbyensis, Dekkera bruxellensis, Saccharomyces cerevisiae, Liquorilactobacillus nagelii, and Leuconostoc mesenteroides—were used in pairs in order to examine their influence on the fermentation progress and the properties of the resulting water kefir products against grains as a control. Thereby, the combination of H. valbyensis and L. mesenteroides provided the best-rated water kefir beverage in terms of taste and low ethanol concentrations at the same time. As a further contribution to harmonization and reduction of complexity, the usage of dried figs in the medium was replaced by fig syrup, which could have been proven as an adequate substitute. However, nutritional limitations were faced afterward, and thus, an appropriate supplementation strategy for yeast extract was established. Finally, comparative trials in 5-L scale applying grains as well as a defined microbial consortium showed both water kefir beverages characterized by a pH of 3.14, and lactic acid and aromatic sensory properties. The product resulting from co-culturing outperformed the grain-based one, as the ethanol level was considerably lower in favor of an increased amount of lactic acid. The possibility of achieving a water kefir product by using only two species shows high potential for further detailed research of microbial interactions and thus functionality of water kefir.

show abstract

Analysis of Hop-Derived Thiols in Beer Using On-Fiber Derivatization in Combination with HS-SPME and GC-MS/MS

Cited by 22 publications

References 31 publications

Efficient breeding of industrial brewing yeast strains using CRISPR/Cas9-aided mating-type switching

Efficient breeding of industrial brewing yeast strains using CRISPR/Cas9-aided mating-type switching

Efficient breeding of industrial brewing yeast strains using CRISPR/Cas9-aided mating-type switching

Tradition as a Stepping Stone for a Microbial Defined Water Kefir Fermentation Process: Insights in Cell Growth, Bioflavoring, and Sensory Perception

Contact Info

Product

Resources

About