Malting: Making Scotch Whisky
Producing whisky is no easy task, and decisions made at various stages during the process affect the character of the final dram. Maturation is the biggest contributor to the flavour and aroma of Scotch whisky, but the complexities in the spirit will affect how it reacts inside the cask, and a number of flavour compounds will be produced at all stages in the process.
Whereas gin producers most often rely on a pure, clean distillate to be a blank canvas for the flavour of the botanicals, Scotch whisky distilleries focus hugely on the character of the spirit itself. Before distillation, the wash is a complex broth of water, alcohol and a variety of flavour compounds known as ‘congeners’, which have been obtained over the course of the production process. The art (and science!) of distillation lies in carefully controlling the process so that only the desirable congeners are retained in the distillate.
Malting
Yeasts produce alcohol and carbon dioxide as they consume sugar, and the first step on the road to whisky is to produce a rich source of soluble sugar to feed the process. This is done by encouraging barley—a rich source of starch—to germinate. This triggers the development of diastase enzymes in the grain, a process known as malting. These enzymes will be used later on in the process to convert the starch to sugar.
Seed germination requires moisture and is affected by temperature. Traditionally, the barley is steeped in water for 2-4 days, and then encouraged to germinate on the ‘malting floor’ for a further 4-5 days. Workers would go up and down the malting floor with flat wooden shovels—turning the germinating barley to keep it properly oxygenated, dissipate heat and prevent the fine roots from becoming entwined and creating an immovable thick matted slab.
This long process eventually took its toll on distillery workers, who were known to develop a condition they called ‘monkey shoulder’ where one arm hung lower than the other. Purists may argue against automation—but at least it means this deformity isn’t to be seen anymore!
When the barley is nearly ready to sprout, heat is used to halt germination. For this the ‘green malt’ is transferred from the malting floor to the drying kiln where hot air, and sometimes smoke if a peat fire is being used, is drawn through the grain. After a day or two, its water contents falls from about 45% to 5% and it becomes brittle and easily crushed.
Temperature control is critical at this stage, partly to ensure the grain’s natural enzymes are not destroyed prior to mashing, but also because the degree of ‘toasting’ that takes place will ultimately influence the flavour of the whisky.
Cost-effectiveness means most distilleries will now buy in malted barley from large-scale producers, although individuality is not lost as each will specify precisely how they want their grain to be treated.
If you are able to visit a distillery, look out for the traditional pagoda chimney, even if in most cases it will be purely decorative. These stand as a mute reminder of the automation and centralisation that has transformed so much of the whisky industry.
Many tasks—from malting to coopering—are now undertaken off-site, and where most activities were once operated by hand and monitored by eye, automation and computers are now often used to improve efficiency and maintain quality control. Yet a few distilleries still maintain traditional methods, which we think holds a certain charm!
In the next article of our Exploring Whisky blog series, we look at the effect and impact of using peat the process of making Scotch whisky…
Further Reading:
Single Malt Whisky Production - Diffords Guide