Producing whisky is no easy task, and decisions made at various stages during the process affect the character of the final dram. While maturation is the biggest contributor to the flavour and aroma of Scotch whisky, the complexities developed in the spirit beforehand will affect how it reacts inside the cask. Flavour compounds are produced at every stage in the process, beginning with the very first step: malting.
From Barley to Malt
Whereas gin producers most often rely on a pure, clean distillate as a blank canvas for botanical flavours, Scotch whisky distilleries focus heavily on the character of the spirit itself. Before distillation even begins, the wash is a complex mixture of water, alcohol, and various flavour compounds known as 'congeners', which have been developed over the course of production. The foundation of this complexity begins with malting.
Yeasts produce alcohol and carbon dioxide as they consume sugar, so the first step in making whisky is creating a rich source of soluble sugar to feed this process. This is achieved by encouraging barley—a grain rich in starch—to germinate, which triggers the development of diastase enzymes. This process, known as malting, produces enzymes that will later convert the starch into fermentable sugars.
The Traditional Malting Process
Seed germination requires moisture and is affected by temperature. Traditionally, barley is steeped in water for 2-4 days, then encouraged to germinate on the 'malting floor' for a further 4-5 days. Workers would move 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 into an immovable, matted slab.
This labour-intensive 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 due to the repetitive motion. Purists may argue against automation, but at least this particular occupational deformity is no longer seen in distillery workers.
Kilning: Halting Germination
When the barley is nearly ready to sprout, heat is used to halt germination. The 'green malt' is transferred from the malting floor to the drying kiln, where hot air—and sometimes smoke from a peat fire—is drawn through the grain. After a day or two, its water content 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 before mashing, but also because the degree of 'toasting' that takes place will ultimately influence the flavour of the whisky. The use of peat smoke during kilning is what gives certain whiskies their characteristic smoky, phenolic character.
Cost-effectiveness means most distilleries now buy malted barley from large-scale commercial maltsters, although individuality is not lost as each distillery specifies precisely how they want their grain to be treated—including peat levels, kilning temperatures, and barley varieties.
The Pagoda: The Icon of Tradition
If you visit a distillery, look out for the traditional pagoda chimney—even if in most cases it's now purely decorative. These distinctive structures stand as a reminder of the automation and centralisation that has transformed 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 now improve efficiency and maintain quality control. Yet a few distilleries still maintain traditional malting floors, which holds a certain charm.
Milling: Crushing the Malt
Once the barley has been dried and the malting process is complete, the next step is milling. A malt mill crushes the malted barley with rollers to produce a coarse flour called 'grist'. The barley is crushed to maximise the amount of sugar that can be extracted during the next stage: mashing.
If you visit a distillery, look to see whether it uses an original Porteus Malt Mill. Some of these machines are more than 100 years old and still working. These mills were so well-manufactured they never needed replacement or repair—so well-made, in fact, that the company eventually went out of business and closed its doors in 1974, a victim of its own quality.
Mashing: Extracting the Sugars
The malting process produced diastase enzymes in the barley grain, including amylase. These enzymes are crucial to whisky production as they catalyse the breakdown of starches in the barley into maltose—a type of sugar that will feed the yeast during fermentation and eventually produce alcohol.
As enzymes are temperature-sensitive, the crushed grist is mixed with hot water in a large vessel called a mash tun and gently agitated. After approximately an hour, a sugar-rich solution called 'wort' is drained off. A second batch of slightly warmer water is then added to the mash tun to extract more sugar, and further, hotter waters may be used to create the 'sparge', which is kept to be used as the first water for the next mash.
In most distilleries, the mash tun is operated electronically, allowing precise control over temperatures and timing. Glenturret holds the distinction of being the last distillery in Scotland with a manually operated mash tun, maintaining this traditional method.
Nothing Goes to Waste
Once the wort has been extracted for fermentation, what remains—called 'draff'—has traditionally been sent to local farmers as high-protein cattle feed. This symbiotic relationship between distilleries and farmers has existed for centuries. Some large distilleries now dry the draff and burn it as a renewable source of energy, demonstrating how traditional waste products can contribute to more sustainable production methods.
From germinating barley to sugar-rich wort, these initial stages of whisky production lay the foundation for everything that follows. The care taken during malting and mashing directly influences the complexity of flavours that will develop through fermentation, distillation, and ultimately, maturation.
Further Reading
- Single Malt Whisky Production Difford's Guide
- The Science and Commerce of Whisky Ian Buxton & Paul Hughes