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Hops

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Other yeast species can also convert monoterpenes. For example, a strain of ''Kluyveromyces lactis'' was found to reduce geraniol to citronellol. This strain and a strain of ''Torulaspora delbrueckii'' produced linalool from both geraniol and nerol, and could also form geraniol from nerol <ref>[https://www.ncbi.nlm.nih.gov/pubmed/10790686 Biotransformation of monoterpene alcohols by Saccharomyces cerevisiae, Torulaspora delbrueckii and Kluyveromyces lactis. King A1, Richard Dickinson J. 2000.]</ref>. Many species of ''Debaryomyces'', ''Kluyveromyces'', and ''Pichia'' were found to transform geraniol into linalool, and nerol into linalool and alpha-terpineol <ref>[https://www.ncbi.nlm.nih.gov/pubmed/18357555 Biotransformation of acyclic monoterpenoids by Debaryomyces sp., Kluyveromyces sp., and Pichia sp. strains of environmental origin. Ponzoni C, Gasparetti C, Goretti M, Turchetti B, Pagnoni UM, Cramarossa MR, Forti L, Buzzini P. 2008.]</ref>. Colomer et al. (2020) measured the monoterpenes in two experiments before and after inoculating with different strains of ''Brettanomyces'' that had varying degrees of beta-glucosidase activity. They found that the strains with the least beta-glucosidase activity had the least impact on biotransformation, but the increase in beta-citronellol was higher than what has been reported in biotransformation studies with ''Saccharomyces'' <ref>[https://onlinelibrary.wiley.com/doi/full/10.1002/jib.610 Biotransformation of hop derived compounds by Brettanomyces yeast strains. Marc Serra Colomer, Birgitte Funch, Natalia Solodovnikova, Timothy John Hobley, Jochen Förster. 2020. DOI: https://doi.org/10.1002/jib.610.]</ref>. See [[Brettanomyces#Hop_Biotransformation|''Brettanomyces'' hop biotransformation]] for more information.
 
Sulfur-based compounds known as ''thiols'' have also been shown to be produced by yeast fermentation from hop derived precursors (suspected to be S-glutathione). So far, science has found that these include the volatile thiols 3-sulfanyl-4-methylpentan-1-ol (3S4MP; grapefruit) and 3-sulfanyl-4-methylpentyl acetate (3S4MPA; passionfruit, grapefruit). These thiols were found in beers dry hopped separately with Amarillo, Hallertau Blanc, and Mosaic hop varieties. The amounts of these two thiols were higher than expected based on the content of these thiols in the hops alone <ref name="Cibaka_2016" />. See also this [https://www.facebook.com/groups/MilkTheFunk/permalink/1373899592638251/ MTF thread speculating on how ''Brettanomyces'' might produce thiols].
In general, different yeast strains have a large impact on how hops are perceived in the final beer, including both perceived bitterness and flavors. For example, POF+ (phenolic positive) strains of ''[[Saccharomyces|Saccharomyces cerevisiae]]'' tends to mask the hop-derived aromas in dry hopped beers <ref name="Sharp_Presentation" />. A beer hopped with the Tradition hop variety produced fruit flavors when fermented with Abbaye ale yeast, and woody/spicy flavors when fermented with US-05. When the beer was brewed with Citra hops, with US-05 the beer had sweet fruits/citrus flavors and more bitterness, but when fermented with the Abbaye ale strain the beer had a more one dimensional sweet fruit/floral flavor and less bitterness <ref>"Influence of yeast strain on hop aroma development in dry hopped beers." Christina Schönberger, Elisabeth Wiesen, Benedikt Matsche, Barth Innovations Yves Gosselin, Stephan Meulemans, Fermentis. Presentation slides at 35th Congress EBC.</ref>.
See also:
:<youtube height="200" width="300">GCQ22HSDDUQ</youtube> <youtube height="200" width="300">r09eb46k97I</youtube>
 
===Thiols===
Sulfur-based compounds bound to a hydrogen atom known as ''thiols'' have also been shown to be produced by yeast fermentation from hop derived precursors (suspected to be S-glutathione). So far, science has found that these include the volatile thiols 3-sulfanyl-4-methylpentan-1-ol (3S4MP; grapefruit) and 3-sulfanyl-4-methylpentyl acetate (3S4MPA; passionfruit, grapefruit). These thiols were found in beers dry hopped separately with Amarillo, Hallertau Blanc, and Mosaic hop varieties. The amounts of these two thiols were higher than expected based on the content of these thiols in the hops alone <ref name="Cibaka_2016" />. See also this [https://www.facebook.com/groups/MilkTheFunk/permalink/1373899592638251/ MTF thread speculating on how ''Brettanomyces'' might produce thiols].
 
See also:
* [http://scottjanish.com/the-locksmith-utilizing-bioengineered-yeast-and-high-bound-thiol-precersour-hops-and-phantasm-powder-to-thiol-drive-beer/ "The Locksmith: Utilizing Bioengineered Yeast and High Bound Thiol Precersour Hops and Phantasm Powder to Thiol Drive Beer," by Scott Janish.]
* [http://scottjanish.com/thiol-driver/ "Thiol-Driver," by Scott Janish.]
* [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===

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