Malt-Components Enzym

Optimum Activity
°C pH
Gum Substances Glucanases 40-45 4.7-5.0
Proteins Proteases 45-50 5.0-5.2
Starch beta-Amylase 60-65 5.4-5.6
alpha-Amylase 70-75 5.6-5.8

pH and temperature are the key parameters for controlling the enzymatic degradation of malt components.

If you don’t mash in a kettle, the temperature step to a desired target temperature usually is reached by adding hot water (step-infusion) or a boiling partial mash (decoction). Thereby you may have to take into account that -besides the mash- the mashtun has to be heated, too. This heat capacity can be considered as system dependent constant. A good starting point for estimating this value is the mass of the mashtun -without insulation and cold parts (eg. outer casing).

You calculate the necessary temperature or partial mash as follows:

Mashing In
Total grain bill A kg / given
Thermal mass of Mashtun B kg / measured
Temperature C °C / measured
Water for mashing in D L / given
E °C = F + ( 0.32*A + B ) * ( F – C ) / D
Target temperature F °C / given
Infusion with given quantity of water
Starting temperature G °C / measured
Infusions water H L / given
I °C = J + ( 0.32*A + B + D ) * ( J – G ) / H
Target temperature J °C / given
Variant -Infusion with boiling water
Starting temperature K °C / measured
Infusion water L L = ( 0.32*A + B + D ) * ( N – K ) / ( M – N )
Boil temperature M °C / measured
Target temperature N °C / given
Mash O L = 0.8 * A + D + H + …
Starting temperature P °C / measured
Decoction Q L = ( O + B ) * ( S – P ) / ( R – P )
Boil temperature R °C / measured
Target temperature S °C / given

Take into account the drop in starting temperature of the mash, stored in the mashtun (it depends on the insulation and therefore it’s a value of experience).

Note that the Excel brewplanner (available in the download area) can calibrate thermal mass, heat losses and heat input of your system. It thus can calculate temperature drops automatically for you.

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