Changes

In ''Saccharomyces'' species, higher fermentation temperature has been associated with faster fermentation, higher growth rates, and ester formation. [https://onlinelibrary.wiley.com/doi/full/10.1002/jib.565 Tyrawa et al. (2019)] set out to explore the impact of fermentation temperature on 7 beer strains (including BSI Drei and several isolates from commercial sour/saison/lambic beers) and 2 wine strains of ''B. bruxellensis''. Fermentis US-05 and the BSI Drei were used as a controls. Each strain was fermented in autoclaved 100% 2-row malt wort at a starting gravity of 1.050 and fermented at 15°C (59°F) versus 22.5°C (72.5°F) for 28 days. The pitching rate was 1.2 x 10⁷ cells/mL. Each strain was genetically tested to ensure their species was correctly identified and that they were genetically distinct from each other <ref name="Tyrawa_2019">[https://onlinelibrary.wiley.com/doi/full/10.1002/jib.565 The temperature dependent functionality of Brettanomyces bruxellensis strains in wort fermentations. Caroline Tyrawa, Richard Preiss, Meagan Armstrong, George van der Merwe. 2019. DOI: https://doi.org/10.1002/jib.565.]</ref>.

Their results showed that there is a vast diversity in how temperature effects attenuation for different strains of ''B. bruxellensis''. In general, the cooler 15°C (59°F) fermentation temperature slowed the attenuation rate for most strains. The US-05 attenuated the most at both temperatures, with only one saison strain matching that attenuation level when fermented at 22.5°C (72.5°F). This same strain, which was isolated from a commercial USA saison beer, and the BSI Drei strains had fast attenuation rates that were comparative to the US-05 fermentation at both temperatures, while the other strains had lag times of 8-10 days at 15°C (59°F) or 2-4 days at 22.5°C (72.5°F) . Additionally, the colder temperature resulted in a wide variance between strains to ferment different types of sugars, with glucose and fructose being fermented by all strains and a lot more variation for fructose, sucrose, maltose, maltotriose, cellobiose, and maltodextrin. At the warmer temperature, only BSI Drei and both of the wine strains were able to ferment cellobiose, indicating that maybe the environment from which the strains adapted in determines what types of sugars different strains of ''B. bruxellensis'' can ferment <ref name="Tyrawa_2019" />.