Before the brew is sent off to a fermentition tank it is cooled and the spent hops and proteins from the cereal are extracted. After that, the magic begins. Yeast is added to start the transformation of sugars onto alcohol.
Fermentation usually takes 7 to 9 days or up to 14 days for special beers. The longer the fermentation process, the more alcohol is produced. However, with Czech beer, Fermentation goes to up to ¾ of sugar transformation so that yeast are not left too long in the beer to negatively affect taste.
The remaining ¼ being the so called not fermented extract. A characteristic feature of Real Bohemian Lagers is that they retain the pleasant full taste of the original malt extract which is exactly what most foreign lagers with higher alcohol content lack after complete fermentation. Another unique element is that most Real Bohemian lagers retain an open fermentation that has now disappeared from mainstream European brewing.