Changes

There are instances where wort souring fails for seemingly unknown reasons. Use a species or strain of ''Lactobacillus'' that is adapted well to souring wort within 24 hours, such as ''L. plantarum''. The lactic acid bacteria sometimes do not survive well during storage over long periods of time, so viability should be checked for long stored or mishandled cultures. Contamination with yeast can also prevent souring in some instances but not all. The use of hops should be avoided even for hop tolerant species (unless the brewer is experienced enough to predict the souring based on their lactic acid bacteria), and especially avoided if using ''L. plantarum''. Residual iso-alpha acids on the walls of kettle tanks /heat exchangers/piping could be enough to inhibit some strains of ''Lactobacillus'', specifically ''L. plantarum'', so kettles /heat exchangers/piping that have previously held highly hopped wort might need to be scrubbed clean before being used as a souring tank <ref>[https://www.stitcher.com/show/craft-beer-brewing-magazine-podcast/episode/episode-199-alex-flores-of-urban-south-kettle-sours-the-hard-way-85931878 Alex Flores. Craft Beer & Brewing Podcast. Episode 199: Alex Flores of Urban South Kettle-Sours the Hard Way. Retrieved 09/16/2021.]</ref>(~21 mins in)[http://sites.libsyn.com/315398/episode-116-kettle-souring-w-daniel-lepage-from-creature-comforts Bru Lab Podcast Episode 116: Daniel LePage, Director of Quality at Creature Comforts in Athens, Georgia, joins Cade in the lab this week to chat about kettle souring. Retrieved 10/06/2023.](~30 minutes in).

There is no scientific basis for the idea that a small amount of oxygen itself that is dissolved during wort souring has a great effect on the flavors that ''Lactobacillus'' produces. Regardless, some brewers report more consistent results when purging oxygen with CO₂. See [[Lactobacillus#Effects_of_Oxygen|Effects of Oxygen on ''Lactobacillus'']] and [https://www.facebook.com/groups/MilkTheFunk/permalink/1778865588808314/ this MTF thread] that discusses the anecdotal experience of brewers who do not purge with CO2CO₂. The effects of oxygen on the beer could lead to other stability issues with the beer because the exposure to oxygen during wort production is thought to play a role in beer staling (see [[Aging and Storage]]), although hot side aeration is also thought to be a minor problem if at all <ref>[http://beersmith.com/blog/2014/01/31/flavor-stability-in-beer-with-dr-charlie-bamforth-beersmith-podcast-74/ Charlie Bamforth. Interview on BeerSmith about Hot Side Aeration. 01/31/2014. Retrieved 08/18/2017.]</ref>, and the impact of hot side aeration on sour beer has not been studied. Some brewers believe that purging all oxygen out of the system will help to prevent contaminating microbes that are aerobic (microbes that require oxygen) from creating [[Isovaleric_Acid#Kettle_Souring|isobutyric acid]]. Oxygen does not play a role in the production of [[Butyric Acid]] in wort soured beers because this compound is produced by anaerobic bacteria (bacteria that requires the absence of oxygen). Air/dust can carry contaminating microbes, which is a potential problem (see [[Wort_Souring#Contamination_Concerns|Contamination Concerns]] above), however, if the air is filtered somehow before entering the fermenting vessel then the oxygen itself shouldn't pose a problem to souring wort. Follow the links in this paragraph for more information.

Tonia Cornett of 10 Barrel reported having experienced a kettle sour beer becoming "ropy" (see [[Pediococcus#.22Ropy.22_or_.22Sick.22_Beer|Ropiness]]). The issue was resolved by boiling the wort <ref>[https://beerandbrewing.com/podcast-episode-252-tonya-cornett-of-10-barrel-brewing/ Tonia Cornett. Craft Beer & Brewing Magazine podcast episode 252. 08/05/2022. Retrieved 09/16/2022.]</ref>(~38 mins in).