mashing
Decoction mash
Raise a mash to its next temperature step by removing part of it, boiling that portion and returning it — the traditional continental method.
Pronounced de-COCK-shun.
Decoction is one of the few brewing techniques where the practical justification and the flavour justification have come apart. It was developed because it is a repeatable way to hit a temperature step without a thermometer or a heated vessel, and because it suited the undermodified malt of the period. Both of those reasons are gone.
What remains contested is whether it still improves the beer. Many respected brewers hold that it does and continue to decoct; several of the breweries most associated with the technique have moved to step mashing without their beers being widely reported as diminished. BeerHQ records the disagreement rather than resolving it.
What is actually happening
- Take a portion. A measured fraction of the mash — grain and liquid together — is drawn off into a separate vessel. The main mash stays where it is.
- Boil that portion. The removed portion is boiled. This is what develops the deep bready and toasty malt character the method is used for.
- Return it. The boiled portion goes back and mixes in, and the heat it carries raises the whole mash to its next temperature step without any direct heating.
A measured fraction of the thickest part of the mash is drawn off, boiled, and stirred back in. The heat it carries lifts the whole mash to the next rest without any external heating of the main vessel.
Boiling that fraction gelatinises starch that had not converted and generates melanoidins, which many brewers credit for the depth of malt character in traditional Bavarian and Bohemian lager.
Typical conditions
| Temperature | 50–100°C |
|---|---|
| Duration | 2–5 hours |
| Scale | Used at both homebrew and commercial scale |
Ranges, not targets. These describe what is usual across the styles and breweries that use this step, and a value outside the range is a decision rather than an error.
Styles where this step is decisive
- Munich Dunkel
Deep brown Bavarian lager led by rich Munich malt — bready and gently chocolatey, without real roast bitterness.
- Czech premium pale lager
The original pale lager: rich bready malt, generous Saaz hopping and a rounded bitterness that soft Bohemian water makes possible.
- Märzen
A rich amber lager brewed in March for autumn drinking, with deep toasty malt and a clean, firm finish.
- Czech pale lager
The Czech everyday lager: lower in strength than the premium version but keeping the soft bready malt and generous Saaz hopping.
- Czech amber lager
A Bohemian amber lager balancing caramel malt against Saaz hop character, sitting between the pale and dark Czech beers.
- Czech dark lager
A dark Bohemian lager richer and sweeter than its German counterparts, with caramel and light roast over a soft body.
- Schwarzbier
Nearly black but remarkably light on the palate: smooth roast, clean lager finish and none of the heaviness the colour suggests.
- Vienna lager
An amber lager built on gently kilned Vienna malt: toasty and lightly sweet, but finishing clean and dry.
- Dortmunder Export
A pale lager sitting between Helles and Pils: fuller and firmer than the first, softer and less bitter than the second.
- Festbier
The golden, stronger lager actually served at modern Oktoberfest — malt-forward and smooth, but pale rather than amber.
- Bock
A strong, dark, malt-dominated lager with deep bread-crust and toasty character and only enough hop to keep it from being sweet.
- Doppelbock
Intensely malty strong lager, dense with bread crust, caramel and dark fruit, and remarkably clean for its strength.
- Helles Bock
A pale, strong lager with the body of a bock but a brighter, more hop-balanced character — traditionally a spring beer.
- Weissbier
Bavarian wheat beer defined by its yeast: pronounced banana and clove over a soft, cloudy, highly carbonated body.
Related steps and concepts
- Step mash — The modern method that replaced it in most breweries.
- Melanoidin — The compound group credited with its effect.
- Modification — Why it was originally necessary.
Also at the mashing stage
Infusion mash · Kettle souring · Mash pH adjustment · Mash-out · Mashing · Sour mashing · Step mash · Turbid mashing · Water treatment
See the whole process in order on how beer is made.
Last reviewed 2026-08-16.
Evidence
What BeerHQ knows about this, and how. Every statement carries the state of the evidence behind it rather than being presented flatly as fact.
Whether decoction mashing produces a malt character that a well-executed step mash with modern malt cannot is genuinely disputed within the trade.
— Many traditional brewers and a substantial body of brewing literature hold that boiling part of the mash develops melanoidin character that cannot be reproduced otherwise.
— Several breweries historically associated with decoction have moved to step mashing without their beers being widely reported as diminished, and blind comparisons have not established a consistent difference.
The practical justifications for decoction — hitting temperature steps without a thermometer, working with undermodified malt — have both disappeared. What remains contested is whether the flavour justification stands alone.
Genuinely contested Credible sources disagree, so both positions are given rather than one.
Sources: Technology Brewing and Malting — print; The Oxford Companion to Beer — print