Whisky is made by extracting the sugars from raw grains. For example, with malt whisky, distillers will allow barley to begin the germination process. The barley is moistened so that it will begin to sprout. This process, which encourages the production of an enzyme that works to turn the grain’s starches into sugar, is known as malting.
During the mashing stage, the sugars are removed from the grain by placing them in a mash tub along with hot water. The mixture is then agitated to create a porridge-like product known as mash.
Fermentation is the process during which the sugars are turned into alcohol. The mash is placed in a vat known as a washback and yeast is added to begin the fermentation process, which can take 48 to 96 hours. Different types of yeast and fermentation times will influence the flavor of the whisky. Once fermentation has been completed, distillers are left with a liquid or wash that has an ABV of 7-10%.
The distillation is used to increase the alcohol content of the mash, however, it can also create unpleasant smells and flavors. Stills, usually made of copper, are used to help remove these less than desirable effects. There are two main types of stills used in whisky production.