Whisky: How is it Made
Different styles of whisky – or whiskey – are made all over the world. But how is this ever-popular spirit made? Find out in our handy guide.
From Scotland to Japan, many countries around the world produce their own unique styles of whisky. While many parts of the production process can vary to create these different styles, the main steps are more or less the same. Read on to discover what happens inside a whisky distillery to create your favourite dram.
Malting is the first step in the production of whisky made from barley, typically called malt whiskies. Starch is key here, and distillers need to get the barley grain to ‘unpack’ the starch stored inside them. So they use a process called ‘malting’. The barley grains are placed in a warm, damp room, which makes them start to sprout. This activates enzymes that will ultimately convert the starch to sugar – vital for fermentation. After a few days, the process is ended by heating the room and drying out the now-malted barley.
In the case of peated whisky, this drying process involves burning dried peat, which releases smoke. The smoke comes into contact with the barley, and the phenolic compounds in the peat smoke are absorbed by the barley grains. These compounds are responsible for the distinctive smoky flavour in the final whisky.
Mashing is how a distiller extracts sugar from their malted or cooked grains – and this is where the enzymes come in. The malted barley is ground into a coarse flour and mixed with hot water. As the starch dissolves in the liquid, the enzymes convert it into sugar, producing a sweet liquid called wort.
For whisky made with other types of grain, this is normally where the process starts. However, because the grains have not been malted, their enzymes have not been activated. And so, whisky distillers will either add a portion of malted barley after the grain-water mixture has cooled, or, if permitted, use enzymes brought in from specialist suppliers.
Fermentation occurs when the sweet wort is combined with yeast, which converts the sugar in the liquid to alcohol. For whisky, this is done in large vats called washbacks, and typically takes 48 to 96 hours, producing a liquid that’s around 7-10% ABV. The length of time and the type of yeast used results in different flavours in the finished whisky, so distillers can choose the best combination to produce their desired whisky style.
Distillation does two things: it increases the alcohol content of the whisky liquid, and it removes unwanted flavours and aromas. The process takes place in copper stills – either a pot still, a column still, or both, depending on the style of whisky being made.
Pot stills are most often used to produce malt whisky – it’s a legal requirement for making Scotch whisky – and the liquid must be distilled in batches. It’s heated until the alcohol boils, with the vapour rising up through a pipe, called a lyne arm, to a condenser. Here, it cools enough to turn back into a liquid, which is normally around 20% ABV. The process is then repeated, resulting in a high-quality spirit that’s around 60-70% ABV.
Column stills are used to make bourbon, rye whisky, and other grain whiskies. The process is continuous, so there’s no need for batches like there is with a pot still. The fermented liquid flows downwards through the still, while hot steam rises from the bottom. The heat boils the alcohol, with the vapour passing through to a condenser where it’s collected.
Almost all types of whisky are matured in oak barrels for several years, to give them colour, smoothness and complex flavours. Often, distillers can choose what type of oak they use and how long they mature their whisky for, but some whisky styles are bound by legal requirements. Scotch whisky, for example, must be aged for at least three years, though many premium single malts are matured for much longer periods of time.
Whisky distillers aim to strike the perfect balance between flavours from the type of grain used, and flavours from the oak barrels. To achieve this, they may choose to mature their whisky in barrels that have previously been used for other types of drink – like ex-Sherry casks, which give the finished whisky distinct dried-fruit aromas, or ex-bourbon casks for subtle coconut, vanilla and spice notes.