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Controlling Temperature with Step- and Decoction Mashing PDF Print
Contributed by Hubert Hanghofer   
May 24, 2005 at 01:48 PM
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 brewplanner can calibrate thermal mass, heat losses and heat input of your system. It thus can calculate temperature drops automatically for you.

Last Updated ( Jun 03, 2005 at 09:06 PM )
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