Glossary
Stuck fermentation
A fermentation that stops before reaching its expected final gravity, leaving more residual sugar than intended.
Usual causes are under-pitching, poor yeast health, insufficient wort oxygenation, a temperature drop that caused early flocculation, or a mash run hot enough that little of the extract was fermentable in the first place. The last of those is not a stuck fermentation at all — the yeast finished, there was simply nothing more to eat.
A genuinely stuck fermentation in the package is a hazard rather than an inconvenience: if it restarts after bottling it produces over-carbonation and, in the worst case, bottles that fail.
Related
- Final gravity — What a stuck fermentation leaves too high.
- Gushing — One of its consequences in the package.
- Bottle bomb — The dangerous failure mode.
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.