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Peyer et al. (2017) observed that growth of US-05 was 82% at a pH of 3.51, and 53% at a pH of 3.17. Fermentation was delayed by 2-4 days (the lower the pH, the longer the start of fermentation was delayed). In a co-fermentation of ''Lactobacillus amylovorus'' and US-05, the initial growth of the ''L. amylovorus'' continued for 3 days while the US-05 was delayed. On day 7, the US-05 recovered and continued growth, and the growth of the ''Lactobacillus'' was slowed starting on day 5. This was due to the increase in ethanol from fermentation, lower pH, and the depletion of nutrients for the ''Lactobacillus''. It is also possible that the yeast benefited from the autolysis of the ''Lactobacillus'', which is speculated to have released nutrients that were made available to the yeast <ref name="Peyer_2017" />.
Also found was an increase in [https://en.wikipedia.org/wiki/Diacetyl diacetyl] and [https://en.wikipedia.org/wiki/Acetoin acetoin] in the beers that were co-fermented with ''L. amylovorus'' and US-05 versus the beers that were kettle soured or mash soured. Both of these compounds are responsible for the buttery taste in beer. Normally, after primary fermentation the yeast reduces daicetyl diacetyl to acetoin, which is then converted to butanediol, however during a co-fermentation with ''Lactobacillus'', this conversion was inhibited in this study <ref name="Peyer_2017" />.
Sensorily speaking, the kettle soured beer tasted "more purepurer" with less fewer off-flavors, and a plum-like aroma. The sour mash and kettle sour beers had a lingering sour aftertaste, while the beer co-fermented with ''L. amylovorus'' and US-05 was described as having an astringent aftertaste. This astringent aftertaste was speculated by the authors to be caused by LAB cell autlysisautolysis, which might have also contributed to a more complex flavor profile in the co-fermented beer <ref name="Peyer_2017" />.
See also:
* [https://www.facebook.com/groups/MilkTheFunk/permalink/1739694606058746/ Poster for the referenced Peyer study.]
* [[Mixed_Fermentation#Staggered_Versus_Co-Pitching|Mixed Fermentation Staggered vs Co-pitching]].