No spirit has the complexity and magic of whisky, or whiskey.
The term 'whisky' derives originally from the Gaelic 'uisge beatha', or 'usquebaugh', meaning 'water of life'.
Though the spirit is called whisky, some variants – notably Irish and American – are spelt with the ‘e’.
Diageo offers more than 100 Scotch, Irish, Canadian and American whiskies. Our Scotch portfolio stretches from the precious legacy of silent distilleries, nestled in the Highlands and closed for years, to the global icon of Johnnie Walker – the world’s number one blended Scotch.
In Ireland’s County Antrim is the legendary and picturesque Bushmills. The world’s oldest whiskey distillery, Bushmills was granted its licence in 1608.
Across the Atlantic, Diageo produces award-winning American bourbon whiskies, such as I W Harper and Bulleit, and Canadian whiskey brands including Crown Royal and Seagram’s.
Whiskies are distilled and aged using a fundamentally similar process, yet key and sometimes tiny differences in ingredients and production give each style and brand a unique signature. Here we look at the process used to produce a single malt Scotch whisky.
Malting
Barley is the main raw material in all single malt Scotch whiskies. First, the barley must be put through the process of malting, during which the grain germinates and is kiln-dried.
Traditionally, distilleries would use peat to fuel this drying process, imparting a distinct smoky flavour to the malt. This is still done at certain maltings today and the flavour carries through into the finished whisky. After drying, the malt is left to cool naturally.
Next, the malt is carefully ground to split open the grain without crushing it entirely. This will allow the starch inside to be released during mashing.
Mashing
The malt is now mixed with very hot water in a circular, flat-bottomed vessel known as the Mash Tun. Mashing releases starch, which breaks down into sugar to create a sweet liquid - the wort. A false bottom in the Mash Tun allows the wort to drain off once mashing is complete.
Fermentation
Yeast is now added to the wort, starting a fermentation process to convert sugar into alcohol. This process normally takes place in large wooden vats or Washbacks, and can last several days. The fermented liquid, with an alcoholic strength similar to a weak beer, will be called ‘wash’.
Distillation
The unmistakable shape of a copper still tells us much about the process of distilling, a two stage batch process . A large volume of alcoholic liquid - the wash - is heated to boil off a small amount of spirit. This spirit is condensed, either in a series of thin copper tubes or in an old fashioned ‘worm’, before undergoing a second distillation, which gives the spirit both strength and flavour.
Eventually we are left with a fine, high quality spirit. It retains the character of its raw ingredients and the unique fingerprint of the distillery, but it is still years from becoming a whisky.
Maturation
The spirit needs to mature in an oak cask in Scotland for at least three years before it qualifies as whisky. Most distilleries leave their whiskies to mature for much longer, often between 10 and 20 years. During this time the cask ‘breathes’, giving flavour and colour to the whisky. Scotch also loses volume and alcohol during this process – giving off something called ‘the Angel’s Share’.
Most single malt whisky casks have been used previously for either sherry or American bourbon, though there is a great deal of variety - it has become popular to ‘finish’ some specialty whiskies by moving them to a different type of cask for several years once they reach maturity.