Glossary
Krausen
The thick, rocky head of foam that forms on fermenting beer at the height of activity.
Pronounced KROY-zen.
Also called kraeusen, high krausen.
High krausen is the peak of the fermentation, and its collapse is the traditional visual signal that the most vigorous phase has passed. The brown scum that gathers on it carries bitter, harsh compounds, which is why open-fermenting breweries skim it.
Related
- Fermentation — The stage it marks.
- Krausening — Using actively fermenting beer to carbonate.
- Open fermentation — The tradition in which krausen is skimmed.
More vocabulary
Arrested fermentation · Barrel ageing · Batch sparging · Biotransformation · Blending · Bottle conditioning · Bottom fermentation · Burtonisation · Cask conditioning · Centrifugation
See every term on the glossary index.
Last reviewed 2026-08-16.