The Kettle Souring Method
What is the Kettle Sour?
Kettle souring consists in lowering the pH of the wort to the desired level of acidity, with the activity of the lactobacillus.
How to do?
Start like classic brewday and after the mash transfer the wort to the kettle and boil for 15 minutes (to sterilize it), chill the wort to 37° C (98 °F) then inoculate the lactobacillus, keep the temperature of 37 °C/98 °F for 48 hours or until the wort is acidified.
When the desired PH level has been reached, you can continue with the normal brewing process: boil the wort, add the hops and inoculate your favorite yeast strain!
The result is a beer with a clean acidity that does not characterize your beer with any intense aromatic compounds or particular esters.
This method gives the chance to experiment with a lot of ingredients, following different styles. You can play with fruit additions, double dry hopping or special yeast strains!
Our tip: if you don't have lactobacillus in your lab, you can just add a few pounds of unmilled pale ale malt in a cotton bag and leave it to infuse in the wort. In fact, all basic barley malts contain lactobacillus. The result will be exceptional!