We make our line of twelve-degree fruit sours using the kettle souring method. This means that we first inoculate the wort with a pure culture of lactobacilli, which create lactic acid through their activity and thereby lower the pH, similar to the process of making kefir. When the required level of acidity is reached, the lactobacilli are eliminated by further boil. Then we ferment the beer again, this time with standard brewing yeast. A large dose of fruit is then added in the later phase of fermentation – in this beer passion fruit and guava, which together provide a very distinctive profile full of juicy tropical fruit flavour.