In part 2 of this series I will cover the traditional method for making sour beers. Last week in part 1, I covered Kettle Souring which is a relatively quick way to make many sour beer styles.
Last week I covered the “Kettle Sour” method where you add the bacteria to your wort up front, let it sour for a few days and then bring it to a boil to kill off the souring yeast or bacteria (and add boil hops). You then follow by adding traditional brewing yeast and fermenting the beer to completion. This method is great for creating a quick lactic acid flavor and also has the advantage of taking only a few extra days to complete. However it does not create the same depth and complexity of flavor you get from traditional sour beer methods.
Traditional Sour Beer Making
This week I’m going to discuss the traditional method for making sour beer which involves fermenting the beer using traditional brewing yeast first, and then adding some form of bacteria followed by an extended aging period. This method can take much longer – from a few months to several years, but it does create a depth and complexity in the finished beer that is not present in a typical kettle sour beer.
To create a traditional sour beer the entire process is the same as creating any beer. You create your wort using either an all grain or extract base, boil it with hops, cool it, aerate it and pitch your selected beer brewing yeast. Then let the beer continue to ferment through at least the finish of primary fermentation until you reach your target gravity.
Now take the finished beer and pitch your selected bacteria into it – typically Brettanomyces (also called Brett) is used as the primary souring agent. It is technically a yeast that provides a fairly restrained and clean lactic acid flavor with a slightly fruity finish. Because the Brett is pitched into a beer that has already been fermented and also contains hops, it will sour much more slowly than the kettle sour option we discussed in part 1.
Other souring bacteria can also be added depending on the level of “funk” you want to create in the finished beer. Lactobacillus (lacto) and Pediococcus (Pedio) are the most common of these. Both produce a solid amount of lactic acid. Pediococcus takes much longer to complete than Lacto but also has a much higher environmental tolerance. For example Lacto does not do well in beer with bitterness levels above 10.
Pedio also does not clean up after itself well which is why it is typically used in combination with Brett to ensure that off flavors are dealt with including high levels of diacetyl and grape juice off flavors. Pedio can also lead to an extended period of time where the beer smells and tastes spoiled, but don’t dump the beer – age will eventually reduce the funk.
Wild yeast can also be used for making sour beers often in combination with open fermentation. Most wild yeasts and bacteria will ferment the beer but also produce sour flavors. The main problem with wild yeast is that it is unpredictable. You don’t know what yeast or bacteria is going into the beer, which can sometimes produce poor results with substantial off flavors.
As mentioned early in the article, traditional sour beers require extended aging. Because the bacteria/yeast is pitched into an already fermented beer which has lower pH and few fermentable sugars left, it will take much longer to produce the lactic acid that sours the beer. Also more off flavors are produced, which take additional time to smooth out. So if you are using the traditional method, I recommend planning several months or longer to complete that beer.
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