Krausening is a traditional German method for carbonating beers without using sugars or other adjuncts. Instead actively fermenting malt wort is added to the fermented beer to provide the malted sugars needed for carbonation.
The History of Krausening
The “Reinheitsgebot”, or German purity law, originated in Bavaria in 1516. It specifies that beer may only be made from the three basic ingredients: malt, hops, and water. Interestingly yeast was left out of the original law as it was unknown until Louis Pasteur discovered microorganisms in the late 1800’s. It was recently replaced by the “Biergesetz” in 1993, which also allows the use of malted wheat and cane sugar, though the term “Reinheitsgebot” is more commonly used.
Since sugars were not allowed in beer, malt wort was used instead. Krausening was widely used in Germany particularly for lagers. Many lagers are cold fermented and aged, often causing the yeast to go dormant. By adding actively fermenting wort for carbonation the lager could be properly carbonated. Krausening was less commonly used in Kolsch or Alt, as these ales were fermented at warmer temperatures leaving active yeast.
Read More at: Krausening Home Brewed Beer | Home Brewing Beer Blog by BeerSmith