Glossary
The boil
Boiling wort for typically 60–90 minutes, which isomerises hop acids, sterilises the wort, coagulates protein, drives off unwanted volatiles and concentrates the extract.
Also called boiling, rolling boil.
The full record
The boil has its own catalogue entry with the detail this page summarises — causes, thresholds, related styles and evidence.
The boil — Boil the wort to isomerise hop acids, sterilise it, coagulate protein, drive off unwanted volatiles and concentrate the extract to the target gravity.
The boil does at least five jobs at once, which is why it is difficult to shorten. Bitterness only exists because alpha acids isomerise at boiling temperature; DMS precursors only leave as vapour from an open, vigorous boil; and the hot break — proteins coagulating and dropping out — is what allows the finished beer to be clear.
Related
- Isomerisation — The reaction that creates bitterness.
- Hot break — The protein coagulation it causes.
- DMS — The off-flavour a vigorous boil drives off.
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.