Mash Temperature
The biggest lever on your beer's body and finish
Mash temperature is how you control whether your beer finishes dry or full-bodied. Lower temps (around 63–65°C) produce more fermentable sugars: lighter body, lower FG, drier finish. Higher temps (68–72°C) produce more unfermentable dextrins: fuller body, higher FG, sweeter finish.
In the recipe builder, changing the mash temperature updates your predicted FG and ABV in real time. We offer three models for this, and you can pick the one that matches how much precision you want.
| Temp | Linear | Enzyme | ODE |
|---|---|---|---|
| 60°C | 82% | 80% | 76% |
| 65°C | 77% | 77% | 77% |
| 67°C | 75% | 75% | 75% |
| 70°C | 72% | 69% | 69% |
| 75°C | 67% | 42% | 36% |
| 80°C | 62% | 13% | 3% |
The Two Enzymes
It all comes down to two enzymes in the mash: beta-amylase (peaks at ~63°C, produces fermentable maltose) and alpha-amylase (peaks at ~70°C, produces non-fermentable dextrins). The ratio of their activity determines your wort's sugar composition.
Three Models
Linear default
The simplest model. About 1% attenuation change per °C from a 67°C reference. Works well in the normal brewing range (64–70°C) and matches what most calculators do. Falls apart at extremes. It still predicts 62% attenuation at 80°C, which isn't physically realistic since both enzymes are dead by then.
Enzyme Kinetics
unique to Brewing.ItModels both enzymes with temperature-dependent activity (Gaussian curves) and thermal denaturation (Arrhenius kinetics). Beta-amylase has a half-life of ~14 minutes at 72°C and dies fast. Alpha-amylase is essentially immortal at mash temps (half-life measured in days at 67°C). 13% of beta-amylase is a thermostable isoform that never denatures. This model naturally drops to near-zero fermentability at 80°C+.
ODE Kinetics
unique to Brewing.ItThe full simulation. Tracks three sugar species (starch → dextrins → maltose) through coupled differential equations. Captures substrate depletion, the alpha-to-beta conversion pipeline, and accumulated denaturation across step mash schedules. If beta loses 50% activity during a 67°C rest, the 72°C mashout starts with only 50%.
Where This Comes From
The enzyme kinetics parameters are based on published brewing science research into amylase activity, thermal denaturation rates, and thermostable enzyme fractions. The Braukaiser mash temperature studies at braukaiser.com were also a key reference.
See all the numbers come together in real time.
See this in the recipe builder