Cereal grains are the staple ingredients of whisky because they provide the starch which becomes alcohol. Scotch can be made from wheat, oat, rye, maize or corn, but to be a Single Malt Scotch Whisky the grain must be barley. For generations, barley was grown by the distilleries themselves or on surrounding farmland. In some cases, landowners built distilleries to create a market for the crops produced by their tenants. Today, whisky is made using barley from all over Scotland, England and Europe.

Barley from Britain is grown mainly on the east coast where the light sandy soils and lower rainfall provide the ideal conditions to produce the high-quality grain suitable for malting – one with a large corn size, and so more of those essential starches. Barley is graded on a scale of 1–9 for quality and consistency, and only the top three grades are suitable for malting. Once ripe, the barley is harvested and dried to remove all but 12% of the moisture so it can be stored, but still retain the ability to germinate at the next stage: malting.

Malting is the first step in turning barley into whisky, and it begins with steeping. In the field, barley will take weeks or even months to begin germinating. By immersing the barley in water three times, with air breaks in between, the grain can be tricked into germinating in a matter of days. The maltster will vary the length of time underwater and the duration of the air rests to ensure the optimum germination. After steeping, the barley is cast into large drums where cool, humidified air is blown through it to control the temperature.

Over five days, the barley sprouts, breaking down the cell walls within the gain and producing enzymes which will eventually convert the starch into soluble sugars known as maltose at the mashing stage. These sugars are meant to give the young plant the best start in life, and the maltster’s true skill lies in allowing germination to progress to a point where the cell walls have broken down, but the growing plant has not yet used too much of the starch. To prevent full germination and preserve the sugars, the barley must be heated and dried: this is done through kilning. In the past, the design of these kilns led to the installation of the distinctive distillery pagoda roof. As the main form of fuel up until the late 19th century, distilleries burned peat or coal in an open kiln to dry their barley and so imparted the salty reek for which many whiskies became famous for. If a distillery wanted unpeated malt, they used a closed kiln. Nowadays, gas is used to produce hot air which dries the grain, and peat smoke is introduced depending on the style of the whisky.

The grist is fed into the mash tun and hot water is then added, working with the enzymes from the malting stage to dissolve the sugars. The optimum heat at which the enzymes will break down the starch is known as the ‘strike point’. Control of this temperature is vital because if the water is too hot it will kill the enzymes. This process is called mashing and the resulting liquid, not too dissimilar to barley water, is called the wort.

The wort is then drained off through the perforated floor of the mash tun and cooled to between 16 and 20 degrees centigrade ready for the next stage. The remaining barley husks are sent for processing into draff: a by-product which has been used as a nutritious cattle feed for probably as long as man has fermented grain alcohol and kept cattle. Up until this point, no alcohol has been produced – but that changes at the next stage.

Distillation is the ancient technique of heating a liquid to separate its component substances. To make a Single Malt Scotch Whisky, Scottish distillers must use a pot still made of copper in a process known as batch distillation. To begin with, the wash is heated in a wash still and when it reaches 78°C the alcohol boils and vapour rises into a condenser. The result is a liquid known as ‘low wines’ with a much higher alcohol content – around 23% ABV. This is transferred to a second still called the ‘low wines’ or ‘spirit’ still where the process is repeated to yield a liquid that is around 70% ABV. During this second distillation, the distiller must know when to separate the ‘middle cut’ or ‘main run’ of the spirit from the early ‘foreshots’ and the ‘feints’ or ‘after shots,’ which contain less desirable components.

Each distillery has its own cut point which influences the character of its whisky – as it’s the middle cut of the distillation, known as New Make or the Heart of the run, that goes on to mature in oak casks. The shape, size and number of stills and how the distillate is condensed can have an important influence on the flavour and character of the final spirit, because of the liquid’s contact with the copper. Tall stills or stills with a lye pipe which angles upwards allow greater reflux, giving a lighter spirit. Stills with a smaller surface area or a downwards sloping lye pipe tend to produce a heavier spirit.