Glossary
Kettle souring
Souring wort with Lactobacillus in the kettle before the boil, then boiling to kill the bacteria and fermenting clean.
Also called kettle sour, quick souring, sour worting.
The full record
Kettle souring has its own catalogue entry with the detail this page summarises — causes, thresholds, related styles and evidence.
Kettle souring — Sour wort with Lactobacillus before the boil, then boil to kill the bacteria and ferment clean — producing lactic acidity in days rather than years.
The technique produces lactic acidity in a day or two rather than the months or years a mixed or spontaneous fermentation requires, and because the boil kills the bacteria there is no risk of them escaping into the brewery.
It also means the finished beer contains no live souring culture. That is why a kettle-soured gose is a fresh beer with a short window rather than a cellaring candidate — nothing is still working in the package, so nothing develops.
Related
- Lactobacillus — The organism used.
- Mixed fermentation — The slow alternative that leaves live culture.
- Gose — A style now usually made this way.
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.