Single Malt Scotch Whisky Production

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How is Single Malt Scotch Whisky made

Words by Simon Difford

There are over 100 different single malt whisky distilleries in Scotland, each producing their own distinctively different whiskies. However, broadly speaking they all follow the same ten distinct stages in the production of their malt whisky.

Each of the ten stages of single malt Scotch whisky production are summarised below with links to in-depth explanations and further information.

1. The raw ingredient - barley

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The quality of the finished malt whisky starts with the quality of the raw materials - barley, water, yeast (and spirit caramel). Strict regulations governing the production of single malt Scotch whisky dictate that barley is the only permitted grain. Scotch whisky distillers are very exacting about both the quality and the yield of the barley they use. More on barley and whiskey...

2. Malting

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The barley must be partially germinated (sprouted) before it can release its starch reserves to be converted into fermentable sugars, but then dried by heat to arrest this germination before the grain uses the sugars to grow. This germination and drying process is called malting. The type of fuel, particularly smoke from peat if used during kilning, will greatly affect a whisky's character. More about malting and peat reek...

3. Milling

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After malting the malted barley, which is as crispy as well-done toast, is milled into powder known as 'grist'. The consistency of this grist is crucial to the extraction of fermentable sugars during the next stage - mashing. More about milling barley...

4. Mashing

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The 'mashing' process takes place in a vessel known as a 'mash tun' and uses heat in the form of hot water to induce natural enzymes (Amylase) to breakdown starch in the grain into fermentable sugars. The sugars and enzymes are then washed from the spent grist using more hot water and filtered out through the sieve-like base of the mashtun to produce a beige-coloured sugary liquid called wort. More about mashing...

5. Water

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Along with barley and yeast, water is one of three key ingredients that make Scotch single malt whisky. What's termed 'production water' is used in the mash tun to make the wort, which goes through to the fermentation stage and eventually ends up in the stills. 'Process water' is used in the boilers to make the steam that heats the stills and to cool the condensers. They often come from different sources and each type of water affects whisky production. More about water in whisky production...

6. Fermentation

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During fermentation yeast converts the fermentable sugars in the wort into alcohol to produce a beer-like liquid called wash. Fermentation is the stage during the whisky-making process when alcohol is produced. (The distillation process which follows merely concentrates that alcohol.) The speed at which the fermentation takes place greatly affects the flavour of the wash and so the finished whisky. More about fermentation and washbacks...

7. Distillation

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Scotch malt whisky is usually distilled twice, and occasionally three times, using batch distillation in copper pot stills. During the last distillation compounds with the lowest boiling points, called foreshots (or heads), boil first. Then comes the heart (middle cut), then the feints (tails) leaving liquid called spent lees in the still. It's the heart that is collected and aged to become whisky. More about distillation...

8. Maturation

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The clear 'new make spirit' to emerge from distillation must be matured for at least 3 years in oak casks with a maximum volume of 700 litres in a Scottish bonded warehouse before it can be called Scotch whisky. During this aging period it undergoes profound changes to emerge as an amber whisky. These changes are influenced by the type of oak, previous cask contents and numerous other variables. More about ageing whisky...

9. Blending/Vatting

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Even single malt Scotch whiskies bottled with a particular age statement are blended from dozens of different casks from the same distillery. Blending (or vatting) different casks of whisky together add complexity and balance to the finished whisky, and most importantly helps ensure consistency from batch to batch and year to year. Blending is an art mastered only with years of experience. More about the art of blending malts...

10. Bottling

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The final stage of production is when the malt is given its own distinctive packaging and branding. The alcoholic strength of the malt is usually reduced with purified water from about 60% alc./vol. cask strength to a minimum of 40% alc./vol. bottling strength. More about bottling malt whisky...

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