A mash tun is used to help with the conversion malt ingredients in water by enzymatic, physical and chemical processes. The relevant malt ingredients are starch, proteins and cell wall substances. The malted grains are mixed in a mash tun with about 150° F hot water “mashing“. The resulting mash is maintained at temperatures around 150° F with constant stirring (so-called protein break to break down the protein).
Mash Tun Chemistry
During this time, the enzymes contained in the malt ensures that fermented maltose ( maltose ) and non-fermentable dextrins are produced from the grain starch. The protein present in the grain is broken down into amino acids during mashing. It must not be heated above 172° F because it would damage the valuable enzymes.
Choosing Your Water
The choice of brewing water prior to mashing in determines the mineral and salt content of the beer. Soft, low-calcium brewing water is better suited for tart beers such as Pilsener or Kölsch. When heating the mash to just over 150° F the starch contained in the mash is enzymatically converted to sugar.
Resting at 150° F (Maltoserast) produces more maltose, which is degraded to ethanol in the subsequent fermentation process. Resting at 160 ° F, on the other hand, promotes the formation of non-fermentable dextrins , which are desired in more full-bodied beers.
With this method, the entire contents of the brewing kettle are heated. The grains are removed from the mash tun into a separate kettle and boiled there, which leads to thermal decomposition of the starch molecules. Subsequently, the partial mash is pumped back into the mash tune and then increases the temperature in the mash tun through to the next rest. This procedure is considered the original mashing process when mash tuns in the brewhouse were still fired directly, as a precise setting of temperature was not possible.