To produce whisky you need three simple ingredients: water, yeast and barley (this can be mixed with rye or corn, I will talk about rye whisky soon) . The best type of barley is the one that produces the most sugar. There are five stages in the process: malting, mashing, fermentation, distillation and maturation.
During malting, the barley is soaked for two to three days in warm water and then traditionally it is spread on the floor of a malting house (like at Laphroaig, although this is only a small part of the whole process, with the rest being done elsewhere with machinery). It is turned regularly to maintain a constant temperature. Nowadays this is mainly carried out in large rotating drums due to the larger scales of production.
When the barley starts to sprout, the germination has to be stopped by drying it in a kiln. Some distilleries then use peat, and the type of peat used and length of drying in the smoke will influence the flavour of the final spirit. You can really tell the difference between the Islay whiskies by their peat levels. I even drove past Laphroaig’s peat moss just to see what the field looks like. (It looks like a field.)
Mashing / Fermentation
The next stage is to add the ground-down malt (grist) to warm water. The water is normally from a pure, reliable, local source – this is why most distilleries around the world are next to a river or lake and why Scotland makes such great whisky. The character of the water can influence the final spirit as it may contain minerals from passing over or through granite, peat or other rock.
The liquid combination of malt and water is called the ‘mash’. It is put into a large vessel called a mash tun and stirred for several hours. During this process, the sugars in the malt dissolve and these are drawn off through the bottom of the mash tun. This process is normally carried out three times, with the water temperature being increased each time to extract the maximum amount of sugar. Only the liquid from the first two times is used. The third lot is put back into the next batch of new grist.
The resulting liquid with the sugars is cooled down before yeast is added. Together they create a liquid called ‘wort’. The fermentation is finished in large wash backs and usually takes two to four days. The fermented liquid (wash) is similar to strong beer and is around 8% ABV.
During distillation the wash goes into the larger wash still and is heated by gas or steam. The liquid vaporises and rises up the still until it reaches the neck, where it condenses. This liquid is called ‘low wine’ and is unusable as it is. The low wines are passed to the second smaller still, called the spirit still. In the spirit still, the alcohol produced is split into three batches. The stills are made from copper and are different shapes that will give different flavours and characteristics to the final spirit.
Alcohols from the beginning of the distillation, ‘foreshots’, are very high in alcohol content. Alcohols from the end, ‘feints’, are weak but also sharp in taste. It is only the alcohol from the middle or ‘heart’ of the distillation that is used and this is removed by a still man and collected through the spirit safe. The decision of what represents the ‘middle cut’ isn’t scientific or achieved mechanically but rather relies on the experience and knowledge of the still man. The foreshots and feints are then mixed with the next batch of low wines and re-distilled. The heart is taken to be matured and will become whisky. This ‘heart’ has an alcoholic strength of 65–70% ABV. In Scotland the wash is distilled twice and in Ireland it is distilled three times (third time lucky?), although there are some exceptions in both countries.
The final stage is to put the spirits into oak casks and store them. The most common types of oak casks are those that have previously been used in the American bourbon and Spanish sherry industries. In Scotland the spirit must mature in casks for a minimum of three years before it is legally allowed to be called whisky. During maturation, the flavours of the spirit blend with natural compounds in the wood cask and this gives the whisky its own specific flavour and aroma. If the casks are stored next to the sea, on an island or in the middle of the Highlands then the air quality, temperature and humidity will be different and will influence the end product. During each year of maturation, the angel’s share is about 2%; this means some of it is lost through natural evaporation.
Unlike wine, whisky doesn’t mature after bottling. During bottling, the alcohol percentage can be reduced by adding water. The minimum percentage of alcohol for whisky is 40%. However, often whisky is not diluted when bottled and this is called cask-strength bottling. Generally, the casks are mixed before bottling, to get a more standardised product, just like great wines. When the whisky comes from just one cask, it is called ‘single cask’.
If you’d like to see more production photos, check Whisky Production in Pictures.
Great article! Thanks Inka!
Hi Keri! Glad you found it useful and thanks for taking the time to comment! x