Changes

Santeri Tenhovirta's master thesis in Food Science from the University of Helsinki examined the pH drop between several species of ''Lactobacillus'' and found similar results regarding ''L. delbruekii'' and the lack of a significant pH drop. The ''Lactobacillus'' samples were allowed to ferment for 48 days in wort by themselves before Fermentis US-05 was pitched to finish the fermentation (the ''Lactobacillus'' samples were never boiled after souring and so the bacteria survived throughout the yeast fermentation). The ''L. delbruekii'' sample got as low as 3.76 pH on day 5 (2 days with only the ''L. delbruekii'' and then 3 days with both ''L. delbruekii'' and US-05), but after 12 days the pH rose up to 4.07, which was close to the control that was fermented with just US-05 and no ''Lactobacillus''. The other samples which included ''L. brevis'', ''L. rhamnosus'', ''L. alimentarius'', ''L. plantarum'', and ''L. buchneri'' all ended up at a final pH between 3.18 3 and 3.54, with all of them achieving a pH lower than 3.8 after 48 hours except for ''L. brevis'', which slowly reached a pH of around 3.4 after about 5 days . The ''L. plantarum'' acidified the wort the fastest, followed by the ''L. rhamnosus''. Interestingly, from day 15 (bottling day) to day 40 (sampling day) most of the acidified beers saw a slight rise in pH anywhere from around 3.18 to 3.3 to 3.4 to 3.5 <ref name="Tenhovirta_masters">[https://mediatum.ub.tum.de/doc/1444162/1444162.pdf Flavor design by advanced fermentation techniques for lactic acid fermented malt-based beverages. Santeri Tenhovirta; master thesis in Food Science from the University of Helsinki. 2019.]</ref>.