Changes

Hop tolerance is not only species dependent, but is also strain dependent. For example, a dissertation by F.J. Methner measured the pH drop of wort that started at a pH of 5.55 from day 3 to day 14 for several strains of ''L. brevis'' at different IBU levels (7,9,11,13 and 18 IBU's). One strain of ''L. brevis'' eventually got down to a pH of 3.8 at day 14 with 7 IBU's, while another strain got down to 3.3 pH at day 14 (with other strains in-between those numbers). At 18 IBU, the relatively hop intolerant ''L. brevis'' strain got down to only 4.2 pH, while another strain got down to 3.7. In general, the higher the IBU, the slower the pH drop. Interestingly, another species called ''L. coryniformis'' was shown to be more hop tolerant than ''L. brevis''. ''L. coryniformis'' dropped the 18 IBU wort down to 3.6 pH over 14 days <ref name="Methner">[https://www.facebook.com/groups/MilkTheFunk/permalink/1537381402956735/ Methner, F.D. Uber Die Aromabildung beim berliner weissebier unter besonderer berucksichtigung von sauren and estern (data reported and translated by Benedikt Koch on Milk THe The Funk Facebook group). 1987.]</ref>. In a separate study, one strain of ''Lacticaseibacillus paracasei'' subsp. ''paracasei'' was able to remain viable in 40 IBU beer <ref>[https://www.sciencedirect.com/science/article/abs/pii/S0963996924011104 Lucas Borges Martins da Silva, Katy Vieira Arruda, Juliana Yumi Suzuki, Marcos Edgar Herkenhoff. Survival of the probiotic strain Lacticaseibacillus paracasei subsp. paracasei F19 in high-hopped beers. Food Research International, 2024, 115040, ISSN 0963-9969, https://doi.org/10.1016/j.foodres.2024.115040.]</ref>