Just three ingredients are needed to make whisky: water, grain and yeast. The kind of grain used varies with the different types of whisky being made, but all whiskies need a small amount of malted barley to begin the fermentation process. The water used for the production of whisky is considered an important factor in making a good whisky. Clean, clear, and free of bad-tasting impurities like iron are the driving factors in selecting water for whisky. Scottish water, known for making fine whisky, is famous for mysterious reasons. Because of the importance of water in how whisky is made, a large number of distilleries are located next to a river or lake.
(Source: How Scotch Whisky is made, www.scotch-whisky.org.uk)
The whisky manufacturing processes
Beyond ingredients, the manufacturing process for whisky typically involved just 6 steps:
- Malting
Barley is a key ingredients in malt whisky and must be treated in a specific way to be able to extract its sugars at a later stage. During this stage, the barley is steeped in water and is able to germinate. The germination process concludes when the barley is dried in a kiln. - Mashing
Following the malting process, the dried barley is ready for mashing. Before fermentation, the sugars within the grain need to be extracted. The grains being used are ground up, and now 3 identified as grist, are combined with hot water in a mash or tub. These large containers have rotating rakes that continuously agitate the mix. During the mashing process, enzymes convert starches into sugars. Once the sugar has been extracted, the liquid – now referred to as wort – is ready to move on the next stage and be turned into alcohol. - Fermenting
During fermentation, the wort is cooled down and then moved to a large container – wood or stainless steel – called a washback. Here, yeast is added. Mixing the wort with yeast converts the sugar into alcohol, referred to as the ‘wash’. This process generally takes between 48-96 hours and can produce a diverse range of flavours depending on fermentation time and the type of yeast strain. The resulting liquid has approximately 7-10% ABV before being distilled. - Distilling
Distillation is done in stills made of copper, where alcohol is separated from water, which results in an increases of the alcoholic strength of the liquid while removing toxic alcohol and other undesirable components. The wash is distilled in the ‘wash still’, which results in a product called “low wines”, which is then distilled in the ‘spirit still’. The second distillation results in the end product called “new make spirit". Most whiskies go through distillation twice, but some go through this process three times. This results in a lighter, more refined spirit. - Maturation
A key element of the production process is aging. All Scotch whisky is aged in wooden containers called casks by law, made from oak. These give the whisky its colour and flavour characteristics. Casks are stored in warehouses for the whisky to mature. Scotch Whisky is aged in oak casks for at least three years, but most Scotch single malt whiskies are aged for a considerable longer period of time. - Bottling
The final stage of the process involves bottling up the whisky. Once it has matured, whisky is bottled at a minimum of 40% ABV. Whisky can be chill filtered to prevent it becoming cloud when ice is added, although this process also removes some of the congeners. Artificial colouring is often conducted for colour consistency, although most of the independent bottlers usually insist on not filtering or colouring for the purpose of authenticity of their product.