13,602
edits
Changes
added more suggested yeast strains
Once the level of acidity is reached (this can be tested with a reliable pH meter, or in the case of using a pure culture can safely be taste tested), the wort is brought to a boil. ''Caution: the wort gravity may also be tested to check for alcohol presence. Alcohol can be more easily boiled off since it boils at 173.1°F or 78.4°C <ref name="boiling_of_alcohol">[http://chemistry.about.com/od/moleculecompoundfacts/f/What-Is-The-Boiling-Point-Of-Alcohol.htm Boiling temperature of ethanol]</ref>.'' The wort may be boiled normally in the case of any style of beer that requires a longer boiling process, or it it may be boiled for no more than a minute or two in the case of making a [[Berliner Weissbier]]. Technically speaking, the wort doesn't need to be boiled at all, as long as it is heat pasteurized <ref name="pasteurization" />, so if alcohol is present then the brewer can choose to heat pasteurize the wort at 170°F (76.6°C) for 15 minutes.
Once the soured wort is heat pasteurized, it can be safely added to the primary fermenting vessel without worries of future infections. The wort is aerated as normal, and brewer's yeast, or [[Brettanomyces]] yeast is then pitched into the wort as normal (usually brewer's yeast is used if infection of equipment is a concern). At a pH of 3.4 or lower, the acidity of the wort can reportedly effect the fermentation of some strains of brewer's yeast <ref name="low ph">[http://www.homebrewtalk.com/f127/no-hop-berliner-weisse-415067/index3.html#post5280971 Michael Tonsmeire on HBT]</ref>. It is recommended to pitch a healthy starter of yeast, possibly with a higher cell count than normal. In the case of using dry yeast, re-hydrating as per the manufacturer's recommendations and using a yeast nutrient like Go-Ferm is recommended. Many yeast strains have been successfully used by MTF members to ferment pre-acidified wort: US05, S04, WY1098/WLP007/OYL-006, Belle Saison, Sacch Trois, Bret brux, B. clausenii, B. custersianus, Bret Drie (BSI), WY3711, and WY3726 to name a few <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1105185972842949/ Conversation on MTF about using specific yeast strains in acidic wort. 7/6/2015.]</ref>.
===Souring in the Primary Fermenter===