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Hops

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====Glycosides====
In addition to terpenes and monoterpene alcohols being found in hops in a free form, they are also present in the form of glycosides, which are flavor compounds that are bound to a sugar molecule. In their bound form, glycosides are flavorless. Studies on hop compounds elude to the possibility of compounds being produced by the glycosidic activity of ''S. cerevisiae'', however direct evidence of glucosidic activity in ''S. cerevisiae'' is lacking. Daenen (2008) reviewed the glycosidic activity of many strains of ''S. cerevisiae'', and found that only a few strains expressed any real glucosidic activity and none that exhibited exo-beta-glucosidase which would be required to break glycosidic bonds in the beer/wort. Daenen did find that enzymatic activity from some strains of ''Brettanomyces'' can efficiently release these bound compounds and release their flavor and aromatic potential <ref name="Praet_2012" />. Beta-glucosidase enzyme can also be added to beer to enhance the breakdown of glycosides and intensify hop-derived flavors and aromas. For example, one study showed an increase in citrus, orange, grapefruit, and tropical pineapple in a Cascade dry hopped beer that had beta-glucosidase enzymes added to it <ref>"Optimizing hop aroma in beer dry hopped with Cascade utilizing glycosidic enzymes (presentation slides)." Kaylyn Kirkpatrick from New Belgium Brewing Co. Young Scientist Symposium, Chico, CA 2016.</ref>. There is also some evidence to support that there is higher glucosidase activity in seeded hops, which are generally not used in the brewing industry <ref>"Seeded and "Unseeded Hops - a Quality Comparison (presentation slides)." Martin Zarnkow. EBC 2015.</ref>. Hops also contain polyhenols that are bound in glycosidic form that could contribute a small amount of bitterness <ref>[https://www.tandfonline.com/doi/abs/10.1080/03610470.2021.2024112?journalCode=ujbc20 Martin Biendl, Stefanie Ritter & Christina Schmidt (2022) Monitoring of Glycosidically Bound Polyphenols in Hops and Hop Products Using LC-MS/MS Technique, Journal of the American Society of Brewing Chemists, DOI: 10.1080/03610470.2021.2024112.]</ref> (see also [https://traffic.libsyn.com/secure/forcedn/thebrulab/056_Applying_the_Science_-_High_Hop_Loads_w_Jordan_Folks.mp3 Bru Lab Podcast Episode 055; Hop Bitterness And Polyphenols w/ Dr. Martin Biendl]).
 
The effects of beta-glucosidase on hops may be limited even in ideal conditions using pure beta-glucosidase that is highly efficient in beer where beta-glucosidase activity by yeast is limited. Sharp et al. (2017) determined that hops contain such a small amount of glycosides that their release doesn't contribute much to hop flavor and aroma. While previous studies focused on hop extracts, they studied glycosides in whole leaf hops for the first time and found non-significant levels of hop-derived monoterpenes from glycosides even when using pure beta-glucosidase extracted from almonds. For example, linalool was increased by 16.5 μg/L when using the highest hopping rate, but this amount has little impact on the overall aroma and flavor of the beer. The terpenes citronellol, terpineol, nerol, and geraniol were also not increased in significant amounts, however, the fatty alcohol 1-octanol (waxy, green, citrus, orange, aldehydic, fruity <ref>[http://www.thegoodscentscompany.com/data/rw1021071.html Octanol. The Good Scents Company. Retrieved 03/31/2017.]</ref>) was increased significantly <ref name="Sharp_2017">[http://onlinelibrary.wiley.com/doi/10.1002/jib.418/abstract The effect of hopping regime, cultivar and β-glucosidase activity on monoterpene alcohol concentrations in wort and beer. Daniel C. Sharp, Jan Steensels, Thomas H. Shellhammer. 2017. DOI: 10.1021/jf2042517.]</ref>. The alcohol octanol can be esterified into octyl acetate, which is a classically "citrusy" aroma, so perhaps certain yeasts can create this ester during mid-fermentation hopping <ref>[https://pubs.acs.org/doi/abs/10.1021/jf2042517 Eric G. Dennis, Robert A. Keyzers, Curtis M. Kalua, Suzanne M. Maffei, Emily L. Nicholson, and Paul K. Boss. 2012.]</ref>.
 
See [[Glycosides]] for more information on glycosides.
===Thiols===
* [https://www.charlesfaram.co.uk/news/technical-article-introduction-to-thiols-in-hop-oils/ Charles Faram Blog; Introduction to Thiols in Hop Oils.]
* [https://www.masterbrewerspodcast.com/227 IRC7 + CRISPR = Cosmic Punch - MBAA podcast with Dr. Laura Burns and Lance Shaner from Omega Yeast.]
 
===Glycosides===
Hops contain glycosides, which are flavor compounds that are bound to a sugar molecule. In their bound form, glycosides are flavorless. Studies on hop compounds elude to the possibility of compounds being produced by the glycosidic activity of ''S. cerevisiae'', however direct evidence of glucosidic activity in ''S. cerevisiae'' is lacking. Daenen (2008) reviewed the glycosidic activity of many strains of ''S. cerevisiae'', and found that only a few strains expressed any real glucosidic activity and none that exhibited exo-beta-glucosidase which would be required to break glycosidic bonds in the beer/wort. Daenen did find that enzymatic activity from some strains of ''Brettanomyces'' can efficiently release these bound compounds and release their flavor and aromatic potential <ref name="Praet_2012" />. Beta-glucosidase enzyme can also be added to beer to enhance the breakdown of glycosides and intensify hop-derived flavors and aromas. For example, one study showed an increase in citrus, orange, grapefruit, and tropical pineapple in a Cascade dry hopped beer that had beta-glucosidase enzymes added to it <ref>"Optimizing hop aroma in beer dry hopped with Cascade utilizing glycosidic enzymes (presentation slides)." Kaylyn Kirkpatrick from New Belgium Brewing Co. Young Scientist Symposium, Chico, CA 2016.</ref>. There is also some evidence to support that there is higher glucosidase activity in seeded hops, which are generally not used in the brewing industry <ref>"Seeded and "Unseeded Hops - a Quality Comparison (presentation slides)." Martin Zarnkow. EBC 2015.</ref>. Hops also contain polyhenols that are bound in glycosidic form that could contribute a small amount of bitterness <ref>[https://www.tandfonline.com/doi/abs/10.1080/03610470.2021.2024112?journalCode=ujbc20 Martin Biendl, Stefanie Ritter & Christina Schmidt (2022) Monitoring of Glycosidically Bound Polyphenols in Hops and Hop Products Using LC-MS/MS Technique, Journal of the American Society of Brewing Chemists, DOI: 10.1080/03610470.2021.2024112.]</ref> (see also [https://traffic.libsyn.com/secure/forcedn/thebrulab/056_Applying_the_Science_-_High_Hop_Loads_w_Jordan_Folks.mp3 Bru Lab Podcast Episode 055; Hop Bitterness And Polyphenols w/ Dr. Martin Biendl]).
 
The effects of beta-glucosidase on hops may be limited even in ideal conditions using pure beta-glucosidase that is highly efficient in beer where beta-glucosidase activity by yeast is limited. Sharp et al. (2017) determined that hops contain such a small amount of glycosides that their release doesn't contribute much to hop flavor and aroma. While previous studies focused on hop extracts, they studied glycosides in whole leaf hops for the first time and found non-significant levels of hop-derived monoterpenes from glycosides even when using pure beta-glucosidase extracted from almonds. For example, linalool was increased by 16.5 μg/L when using the highest hopping rate, but this amount has little impact on the overall aroma and flavor of the beer. The terpenes citronellol, terpineol, nerol, and geraniol were also not increased in significant amounts, however, the fatty alcohol 1-octanol (waxy, green, citrus, orange, aldehydic, fruity <ref>[http://www.thegoodscentscompany.com/data/rw1021071.html Octanol. The Good Scents Company. Retrieved 03/31/2017.]</ref>) was increased significantly <ref name="Sharp_2017">[http://onlinelibrary.wiley.com/doi/10.1002/jib.418/abstract The effect of hopping regime, cultivar and β-glucosidase activity on monoterpene alcohol concentrations in wort and beer. Daniel C. Sharp, Jan Steensels, Thomas H. Shellhammer. 2017. DOI: 10.1021/jf2042517.]</ref>. The alcohol octanol can be esterified into octyl acetate, which is a classically "citrusy" aroma, so perhaps certain yeasts can create this ester during mid-fermentation hopping <ref>[https://pubs.acs.org/doi/abs/10.1021/jf2042517 Eric G. Dennis, Robert A. Keyzers, Curtis M. Kalua, Suzanne M. Maffei, Emily L. Nicholson, and Paul K. Boss. 2012.]</ref>.
 
See [[Glycosides]] for more information on glycosides.
===Lightstruck===
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