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Terpenes and terpenoids (monoterpene alcohols) can also be transformed by fermentation. Studies have found that geraniol and nerol can transform into linalool by a strain of ''S. cerevisiae'', as well as nerol and linalool into alpha-terpineol, which can then by further transformed to terpin. Geraniol can also be converted into citronellol, and the content of geraniol and citronellol can be increased in finished beer by increasing the initial content of geraniol, which is found in higher quantities in some varieties of hops (Citra, for example). Linalool, nerol, and alpha-terpineol gradually decrease during fermentation and aging (perhaps being transformed into ethers), while nerol and citronellol gradually increase. Geraniol also decreases during fermentation, but not as drastically as linalool. It has been hyptothesized that the bioconversion of geraniol into ctironellol could be by means of glycosidic activity (although another study found that glycosidic activity in ''S. cerevisiae'' is not very strong). Post-fermentation dry hopping preserves linalool and alpha-terpineol, and limits citronellol to trace levels <ref name="Praet_2012" />.
Takoi et al. (2012) used Citra hops with a high content of geraniol, and reported a steep decline on geraniol during the first three days of fermentation with a lager yeast. Linalool had a gradual decline, but ended up at higher levels than geraniol in the finished beer. Citronellol had a sharp increase during the first three days of fermentation, and then remained at a stable level until the end of fermentation. However, after storing the beer at 15°C (59°F) for 1 week, the amount of citronellol more than doubled. This indicated that active fermentation may not required for the transformation of geraniol into citronellol <ref>[https://onlinelibrary.wiley.com/doi/abs/10.1002 /j.2050-0416.2010.tb00428.x The Contribution of Geraniol Metabolism to the Citrus Flavour of Beer: Synergy of Geraniol and β‐Citronellol Under Coexistence with Excess Linalool. Kiyoshi Takoi, Yutaka Itoga, Koichiro Koie, Takayuki Kosugi, Masayuki Shimase, Yuta Katayama, Yasuyuki Nakayama, Junji Watari. 2012. DOI: https://doi.org/10.1002/j.2050-0416.2010.tb00428.x.]</ref>. This data is shown below: [[File:Biotransformation Takoi 2012.png|[https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2050-0416.2010.tb00428.x Takoi et al. 2012]]]
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>.