Malt whisky production comprises of four different stages; first starting with malting barley, mixing the ground barley with hot water, fermenting it with yeast and then distilling it twice in large copper pot stills.
Produced using a traditional batch process, malt whisky is made up of three core ingredients; malted barley, yeast and water. The barley first must be malted; steeped in water and then left out on a malting floor to sprout shoots. It is then baked in a kiln to dry it out, with some distilleries, like those in Islay, using peat at this point to give their whiskies distinctly smoky notes.
Having been milled, the ground barley, or grist as it is now known, is mixed with hot water in a mash tun, producing a sugary liquid called wort. This is the basis for the alcohol. The remaining solids are used in agriculture as a nutritious cattle feed. Next, the liquid wort is passed into large vats called washbacks, where yeast is added and allowed to ferment, converting the sugars in the wort into an alcohol around 8% abv, or the ‘wash.’
The final process entails the ‘wash’ to be heated in two stills; the wash still and the spirit still. Only a certain part of the run, where the quality of the spirit is at its highest, is collected and used. The rest is siphoned and re-distilled.
The spirit is then poured into oak casks to age. By law, it cannot be called Scotch unless it has been matured for a minimum of three years in Scotland. If an age is shown on a label of malt whisky, it indicates the least amount of time that all the whisky in the bottle has been matured for. Malt whisky produced at one distillery is sold as single malt whisky; you can also buy blended malt whisky which will be the product of two or more different distilleries.
Whisky is produced in five different regions with each region being known for particular notes or characteristics.
Find out more about malt whisky along the Scotland's Malt Whisky Trail.