How to do Kettle Souring in Brew House?

Kettle souring is a technique that allows brewers to rapidly sour unfermented wort in brewhouse in just a matter of days, often taking only a mere 24 hours. It could not be more simple - after creating wort and conducting a brief boil for sanitation, the wort is cooled to 75 - 95 degrees F (24 - 35 C) and a cultured strain (or blend of strains) of pure lactobacillus is introduced. Once introduced, the lactobacillus will go to work and begin consuming sugars in the wort transforming them into lactic acid, providing the tart flavor we know and love. Given some time, usually 1 to 3 days, the souring will be complete.

Why Use Kettle Souring?
Souring a beer this way has several benefits. First, the time frame. Being able to turn a sour beer in mere days is the obvious benefit. Second, since the wort is soured and then boiled to kill off the lactobacillus, you do not need to worry about infecting any fermentation equipment or contaminating any other batches in your fermentation tank. Finally, since lactobacillus is extremely sensitive to isomerized alpha-acids (as little as 2 IBUs), this method allows you to make a hoppier sour beer than possible with the traditional method.
How to do kettle souring? brew house, brewhouse equipment, steam heated brewhouse, beer kettle

How to do kettle souring? brew house, brewhouse equipment, steam heated brewhouse, beer kettle

Kettle Souring Tips
There are a few techniques that can help to make this method a success every time. Pre-acidification of the wort to pH 4.5 using a food grade acid (lactic or phosphoric) will do wonders in inhibiting other bacterial strains that may be present such as enteric bacteria. This acidification will also hamper the action of an enzyme lactobacillus uses to break down proteins, so your resulting beer will still showcase all the head retention and body that you would expect from the same beer fermented with only Saccharomyces.

To help maintain warm temperatures recommended for the kettle souring process, we suggest using Tiantai steam heated brewhouse for accurate temperature controlling.

Don’t worry if the wort temperature drops to room temperature during the souring, my favorite lactobacillus strain (Omega Yeast Labs OYL-605) works incredibly well at lower temperatures due to its unique blend of bacteria strains. The wort will sour at a slightly slower pace, but it still beats waiting for up to two years!
Make sure that your sanitation practices are impeccable as always, and enjoy your adventure into rapid-turn sour beers with Tiantai brewhouse equipment!

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Emily Gong

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