Investigation of Geraniol Biotransformation by Commercial <i>Saccharomyces</i> Yeast Strains by Two Headspace Techniques: Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS)
Hop-derived volatile organic compounds (VOCs) and their transformation products significantly impact beer flavour and aroma. Geraniol, a key monoterpene alcohol in hops, has been reported to undergo yeast-modulated biotransformation into various terpenoids during fermentation, which impacts the citr...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-03-01
|
| Series: | Fermentation |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2311-5637/9/3/294 |
| _version_ | 1797611827211796480 |
|---|---|
| author | Rebecca Roberts Iuliia Khomenko Graham T. Eyres Phil Bremer Patrick Silcock Emanuela Betta Franco Biasioli |
| author_facet | Rebecca Roberts Iuliia Khomenko Graham T. Eyres Phil Bremer Patrick Silcock Emanuela Betta Franco Biasioli |
| author_sort | Rebecca Roberts |
| collection | DOAJ |
| description | Hop-derived volatile organic compounds (VOCs) and their transformation products significantly impact beer flavour and aroma. Geraniol, a key monoterpene alcohol in hops, has been reported to undergo yeast-modulated biotransformation into various terpenoids during fermentation, which impacts the citrus and floral aromas of the finished beer. This study monitored the evolution of geraniol and its transformation products throughout fermentation to provide insight into differences as a function of yeast species and strain. The headspace concentration of VOCs produced during fermentation in model wort was measured using Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS). In the absence of yeast, only geraniol was detected, and no terpenoid compounds were detected in geraniol-free ferments. During fermentation, the depletion of geraniol was closely followed by the detection of citronellol, citronellyl acetate and geranyl acetate. The concentration of the products and formation behaviour was yeast strain dependent. SPME-GC/MS provided confidence in compound identification. PTR-ToF-MS allowed online monitoring of these transformation products, showing when formation differed between <i>Saccharomyces cerevisiae</i> and <i>Saccharomyces pastorianus</i> yeasts. A better understanding of the ability of different yeast to biotransform hop terpenes will help brewers predict, control, and optimize the aroma of the finished beer. |
| first_indexed | 2024-03-11T06:34:10Z |
| format | Article |
| id | doaj.art-a66d2ed1b5ea48f09e05daa69cea1d27 |
| institution | Directory Open Access Journal |
| issn | 2311-5637 |
| language | English |
| last_indexed | 2024-03-11T06:34:10Z |
| publishDate | 2023-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Fermentation |
| spelling | doaj.art-a66d2ed1b5ea48f09e05daa69cea1d272023-11-17T11:02:40ZengMDPI AGFermentation2311-56372023-03-019329410.3390/fermentation9030294Investigation of Geraniol Biotransformation by Commercial <i>Saccharomyces</i> Yeast Strains by Two Headspace Techniques: Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS)Rebecca Roberts0Iuliia Khomenko1Graham T. Eyres2Phil Bremer3Patrick Silcock4Emanuela Betta5Franco Biasioli6Department of Food Science, University of Otago, P.O. Box 56, Dunedin 9054, New ZealandSensory Quality Unit, Research and Innovation Centre, Fondazione Edmund Mach, 38098 Trento, ItalyDepartment of Food Science, University of Otago, P.O. Box 56, Dunedin 9054, New ZealandDepartment of Food Science, University of Otago, P.O. Box 56, Dunedin 9054, New ZealandDepartment of Food Science, University of Otago, P.O. Box 56, Dunedin 9054, New ZealandSensory Quality Unit, Research and Innovation Centre, Fondazione Edmund Mach, 38098 Trento, ItalySensory Quality Unit, Research and Innovation Centre, Fondazione Edmund Mach, 38098 Trento, ItalyHop-derived volatile organic compounds (VOCs) and their transformation products significantly impact beer flavour and aroma. Geraniol, a key monoterpene alcohol in hops, has been reported to undergo yeast-modulated biotransformation into various terpenoids during fermentation, which impacts the citrus and floral aromas of the finished beer. This study monitored the evolution of geraniol and its transformation products throughout fermentation to provide insight into differences as a function of yeast species and strain. The headspace concentration of VOCs produced during fermentation in model wort was measured using Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS). In the absence of yeast, only geraniol was detected, and no terpenoid compounds were detected in geraniol-free ferments. During fermentation, the depletion of geraniol was closely followed by the detection of citronellol, citronellyl acetate and geranyl acetate. The concentration of the products and formation behaviour was yeast strain dependent. SPME-GC/MS provided confidence in compound identification. PTR-ToF-MS allowed online monitoring of these transformation products, showing when formation differed between <i>Saccharomyces cerevisiae</i> and <i>Saccharomyces pastorianus</i> yeasts. A better understanding of the ability of different yeast to biotransform hop terpenes will help brewers predict, control, and optimize the aroma of the finished beer.https://www.mdpi.com/2311-5637/9/3/294beerfermentationgeraniolbiotransformationSPME-GC/MSPTR-ToF-MS |
| spellingShingle | Rebecca Roberts Iuliia Khomenko Graham T. Eyres Phil Bremer Patrick Silcock Emanuela Betta Franco Biasioli Investigation of Geraniol Biotransformation by Commercial <i>Saccharomyces</i> Yeast Strains by Two Headspace Techniques: Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) Fermentation beer fermentation geraniol biotransformation SPME-GC/MS PTR-ToF-MS |
| title | Investigation of Geraniol Biotransformation by Commercial <i>Saccharomyces</i> Yeast Strains by Two Headspace Techniques: Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) |
| title_full | Investigation of Geraniol Biotransformation by Commercial <i>Saccharomyces</i> Yeast Strains by Two Headspace Techniques: Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) |
| title_fullStr | Investigation of Geraniol Biotransformation by Commercial <i>Saccharomyces</i> Yeast Strains by Two Headspace Techniques: Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) |
| title_full_unstemmed | Investigation of Geraniol Biotransformation by Commercial <i>Saccharomyces</i> Yeast Strains by Two Headspace Techniques: Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) |
| title_short | Investigation of Geraniol Biotransformation by Commercial <i>Saccharomyces</i> Yeast Strains by Two Headspace Techniques: Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) |
| title_sort | investigation of geraniol biotransformation by commercial i saccharomyces i yeast strains by two headspace techniques solid phase microextraction gas chromatography mass spectrometry spme gc ms and proton transfer reaction time of flight mass spectrometry ptr tof ms |
| topic | beer fermentation geraniol biotransformation SPME-GC/MS PTR-ToF-MS |
| url | https://www.mdpi.com/2311-5637/9/3/294 |
| work_keys_str_mv | AT rebeccaroberts investigationofgeraniolbiotransformationbycommercialisaccharomycesiyeaststrainsbytwoheadspacetechniquessolidphasemicroextractiongaschromatographymassspectrometryspmegcmsandprotontransferreactiontimeofflightmassspectrometryptrtofms AT iuliiakhomenko investigationofgeraniolbiotransformationbycommercialisaccharomycesiyeaststrainsbytwoheadspacetechniquessolidphasemicroextractiongaschromatographymassspectrometryspmegcmsandprotontransferreactiontimeofflightmassspectrometryptrtofms AT grahamteyres investigationofgeraniolbiotransformationbycommercialisaccharomycesiyeaststrainsbytwoheadspacetechniquessolidphasemicroextractiongaschromatographymassspectrometryspmegcmsandprotontransferreactiontimeofflightmassspectrometryptrtofms AT philbremer investigationofgeraniolbiotransformationbycommercialisaccharomycesiyeaststrainsbytwoheadspacetechniquessolidphasemicroextractiongaschromatographymassspectrometryspmegcmsandprotontransferreactiontimeofflightmassspectrometryptrtofms AT patricksilcock investigationofgeraniolbiotransformationbycommercialisaccharomycesiyeaststrainsbytwoheadspacetechniquessolidphasemicroextractiongaschromatographymassspectrometryspmegcmsandprotontransferreactiontimeofflightmassspectrometryptrtofms AT emanuelabetta investigationofgeraniolbiotransformationbycommercialisaccharomycesiyeaststrainsbytwoheadspacetechniquessolidphasemicroextractiongaschromatographymassspectrometryspmegcmsandprotontransferreactiontimeofflightmassspectrometryptrtofms AT francobiasioli investigationofgeraniolbiotransformationbycommercialisaccharomycesiyeaststrainsbytwoheadspacetechniquessolidphasemicroextractiongaschromatographymassspectrometryspmegcmsandprotontransferreactiontimeofflightmassspectrometryptrtofms |