mashing
Mashing
Hold milled malt in hot water so the grain’s own enzymes convert its starch into sugars that yeast can ferment.
Also called mash, saccharification.
What is actually happening
Beta-amylase, most active around 60–65 °C, cleaves maltose from the ends of starch chains. Maltose is highly fermentable, so a cooler mash produces a drier, thinner beer.
Alpha-amylase, most active around 68–72 °C, cuts starch chains internally and produces a mix that includes substantial unfermentable dextrin. A hotter mash therefore produces a fuller, sweeter beer from identical grain.
Because both enzymes are working at once and both are being slowly denatured by heat, mash temperature is a continuous control rather than a switch. This is the single most useful lever a brewer has over body without changing the recipe.
Typical conditions
| Temperature | 62–72°C |
|---|---|
| Duration | 45–90 min |
| 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.
What goes wrong here
Risks rather than certainties. This step does not cause these faults; getting it wrong can.
- Unintended sweetness — Beer that finishes sweeter than intended, from under-attenuation, excess crystal malt, or a mash run too warm.
- Stalled fermentation — Fermentation stopping well short of terminal gravity — leaving a sweet, underdeveloped beer and a package-pressure risk.
Questions
Why does mash temperature change how sweet the beer tastes?
It changes what the yeast is given rather than what the yeast does. A mash at 63 °C produces mostly fermentable maltose, so the yeast consumes nearly all of it and the beer finishes dry. A mash at 70 °C produces more dextrin, which no brewing yeast can ferment, so it stays in the beer as body and mild sweetness.
Related steps and concepts
- Lautering — Separating the wort from the grain afterwards.
- Infusion mash — The single-temperature method.
- Step mash — The multi-temperature method.
- Mash temperature — The controlling variable.
- Dextrin — What a hot mash produces more of.
Also at the mashing stage
Decoction mash · Infusion mash · Kettle souring · Mash pH adjustment · Mash-out · Sour mashing · Step mash · Turbid mashing · Water treatment
See the whole process in order on how beer is made.
Last reviewed 2026-08-16.