Cicerone Certified Beer Server Practice Test

What is kettle souring?

1. A method of adding hops to beer

2. An infection that spoils beer

3. A technique to produce a tart flavor by adding souring bacteria before boiling

4. A fermentation style using wild yeast

The correct answer is: A technique to produce a tart flavor by adding souring bacteria before boiling

Kettle souring is a brewing technique that aims to create a tart flavor in beer through the introduction of souring bacteria before the boiling process. This method generally involves adding specific strains of Lactobacillus, a type of lactic acid bacteria, to the wort. The wort is then left to sour for a predetermined period, during which the bacteria produce lactic acid, giving the beer its characteristic sourness. After the desired level of acidity is reached, the wort is boiled to kill the bacteria, followed by the addition of hops and fermentation with yeast. This technique is widely used in styles such as Berliner Weisse and Gose, which are known for their refreshing tartness. By incorporating the souring process before the boil, brewers can achieve a more controlled sour flavor compared to traditional fermentation methods that allow wild yeasts and bacteria to develop during fermentation.