Changes

Colomer et al. (2020) was the first to examine the effects of ''Brettanomyces'' on hops during fermentation. The researchers selected 4 strains of ''B. bruxellensis'' and 1 strain of ''B. anomalus'' that had the genetic markers for producing beta-glucosidase enzyme, and fermented them as a primary fermenter in a non-dry hopped beer, and also performed a second experiment where they inoculated the ''Brettanomyces'' strains in a dry hopped beer that was first fermented out with ''S. cerevisiae''. Monoterpene alcohols were measured before and after inoculation with the 5 strains of ''Brettanomyces''. In both beers, they found a decrease in geraniol and a rise in beta-citronellolafter the inoculation with ''Brettanomyces''. Beta-citranellol reached a level of 31.5 μg/L with one of the strains, which is a much higher level of beta-citronelol citronellol than anything that has been reported with ''S. cerevisiae'', suggesting that some strains of ''Brettanomyces'' might be better at converting monoterpenes from hops than ''Saccharomyces''. See [https://onlinelibrary.wiley.com/doi/full/10.1002/jib.610 Figure 5] in the open access sstudystudy. Interestingly, the strains with the highest beta-glucosidase activity produced the lowest amount of beta-citranellol, indicating that there is not a no link between beta-glucosidase activity in ''Brettanomyces'' and hop biotransformation. This might be due to the fact that most of the beta-glucosidase enzyme is produced within the cell and is not released outside of it . The researchers hypothesized that this conversion could be due to two proteins referred to as BbHye2 and BbHye3 that can be present in ''Brettanomyces'' metabolism <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>.