Whisky Magazine Issue 68
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The mash tun is a vital vessel,accommodating the conversion of starch within the grist into sugars,using a sequence of three,or even four waters at a progressively higher temperatures. But rather than the mashing process,the aim of this article is to explore the design of a mash tun,and the practicalities that enable mashing to take place – Ian Wisniewski reports.
Mash tuns were traditionally fashioned from cast iron, with the move to stainless steel dating from around 20 years ago,though Springbank and Royal Lochnagar are two examples of distilleries still using cast iron. One factor is that cast iron retains heat longer than stainless steel, but this is a difference that can be compensated for.
“Stainless steel is always insulated, basically with a 70mm thick layer of insulation, which is normally mineral wool clad with a light stainless steel sheet,”says Richard Forsyth of Forsyth's,who manufacture distilling equipment.
While stainless steel mash tuns typically feature a matching lid, some are colour co-ordinated with a copper lid, as at Bunnahabhain, Glenfiddich and Auchentoshan. Copper's excellent malleability, and aesthetics, are two advantages.A rare option is no lid at all, practised by distilleries such as Royal Lochnagar and Springbank.
“We don't have a lid on the mashtun. Conversion takes place regardless of the heat above the bed of the mash,”says Springbank's Stuart Robertson.
Mashing begins by combining the first water with grist in a mashing machine (also known as a mixer), and being conducted through a spout into the mash tun.The ‘strike temperature' (ie.
temperature at which water strikes the grist) must be accurate to prevent damaging enzymes within the grist (as they play a vital role in converting starch into sugar). Reaching the exact strike temperature is usually a case of combining hot and cold wat...