Scotch whisky milling equipment: the hammer mill
The hammer mill is usually paired with a mash filter. The husk is not required in a mash filter, and as much flour as possible is required. So, malted barley is crushed in a hammer mill to create as fine a flour as possible. The basic theory is that the finer the flour, the easier it is for the malt enzymes to access the carbohydrates and convert them into shorter-chain fermentable sugars that the yeast can process.
A distillery’s choice of equipment is usually determined by a) the grain(s) they intend to use and b) the style of distillation they’re after. Due to this, there are many combinations of brewing equipment across the industry for milling, mashing and fermenting.
Hammer mills use rectangular pieces of hardened steel to pulverise the grain, which has been fed into the milling chamber. Used by several Scotch and Irish whiskey distilleries, the hammer mill can be used for almost any grain type, including malted, and unmalted grains for pot distillation, as well as maize and other grains used in column still distillation.