Lactic acid bacteria (Lactobacillus)
Term from the Brauwerkstatt brewing glossary, category “Fermentation and yeast”.
Explanation
Bacteria that ferment sugar into lactic acid and make beer sour. They are wanted in Berliner Weisse, gose, lambic and kettle sours. Unwanted, they are an infection – the beer turns unexpectedly sour. Hops inhibit many lactic acid bacteria, which is why sour beer is often soured before hopping.
Work it out yourself
Brewing water calculator – Adjust your tap water to the beer style: the calculator tells you how much calcium chloride, gypsum and lactic acid you need.
Test your knowledge
What does Flanders red ale mature in?
- Clay jars
- Large oak vats called foeders
- Steel tanks
Show answer
Correct: Large oak vats called foeders. Lactic acid bacteria and wild yeasts give it a wine-like acidity. The best known comes from Rodenbach.
What is a kettle sour?
- A beer stored in the kettle
- A beer that tastes of limescale
- A sour beer soured in the kettle before the boil
Show answer
Correct: A sour beer soured in the kettle before the boil. Lactic acid bacteria sour the wort, then it is boiled. This keeps the fermenter free of bacteria.
Which country does the beer style “Catharina sour” come from?
- Brazil
- Canada
- Colombia
Show answer
Correct: Brazil. Brazilian beer style from the state of Santa Catarina: a light, refreshing sour beer that is briefly soured with lactic acid bacteria in the kettle (“kettle sour”) and gets lots of fresh fruit, such as passion fruit, guava or mango.