1. The Grains: Where It All Begins
Although single malt whisky famously uses only barley, other grains also play a key role in making different types of whisky worldwide. Bourbon, for example, must contain at least 51% corn, which gives it a sweeter taste. Rye whisky, especially popular in North America, uses a majority of rye, creating a spicier flavour. Some blends include wheat to soften the overall profile. Irish whiskey often features both malted and unmalted barley. Each grain brings unique flavours and characteristics to the final product.
In the case of single malt whisky, top-quality barley is crucial for creating the depth of flavour that many drinkers seek. Distilleries frequently partner with local farmers to ensure consistent grain quality. Whether it’s barley, corn, rye, or wheat, the first step is always the same: farmers grow the grain, harvest it, and prepare it for the next stages. The aim is to gather grains that will provide enough starches, and later sugars, so the whisky can develop a full and balanced character.
Distilleries carefully choose the grains, or grain combinations, that set the tone for the final whisky. To discover how these choices shape different styles, check out The Guide to Exploring Different Types of Whisky to learn more about the results of those choices.
2. Malting: Awakening the Grain
When barley is used (particularly for single malts), it goes through a special process called malting. The grain is soaked in water to convince it that spring has arrived, triggering germination. As the barley sprouts, it releases enzymes that convert the stored starches into soluble sugars. These sugars will be vital later on for creating alcohol. Once germination has reached the right point, distilleries dry the barley to stop further growth. Often, hot air is used for drying, but some distilleries burn peat, which infuses the grain with a smoky aroma. At the end of malting, the sprouted and dried barley is called malted barley.
Other grains like corn, rye, or wheat typically do not require a malting stage. Instead, they might be milled directly or cooked to release their starches. However, no matter which grain is chosen, the goal remains the same: prepare the material so that enough fermentable sugars can be extracted in the next step.
3. Mashing: Unlocking the Sugars
Once the grains reach the distillery, they are milled into coarse pieces. Barley is crushed to form a grist that lets hot water reach the sugars without turning everything into a fine powder. In the case of corn, rye, or wheat, the grains are often ground more thoroughly or cooked to help break down their starches. After milling, the grist is placed in a mash tun, where hot water is added. This process, called mashing, draws out the sugars to create a sweet liquid known as wort. Think of it like making tea: hot water flows through the grains, dissolving the sugars and flavour compounds.
Some distilleries add water at different temperatures in multiple stages to extract as many sugars as possible. When the run-off liquid is collected, it’s cooled before heading to fermentation. How carefully the grains are milled and mashed can significantly affect the clarity, flavour, and overall efficiency of the process.
- The temperature in the mash tun matters. Too hot or too cool can affect how much sugar is extracted but it is often around 65 degrees Celcius (149°F).
- Different distilleries have unique mashing routines to refine or highlight certain flavour notes.
The wort flows on to the next stage, carrying the potential for the final whisky’s character.
4. Fermentation: Yeast Takes Over
Fermentation turns the sugary wort into a form of alcoholic liquid. Distilleries pump the cooled wort into fermenters or washbacks and add yeast. Yeast is a living organism that consumes the sugar, producing alcohol, carbon dioxide, and various aroma compounds called esters. Depending on the yeast strain, the fermentation temperature, and the length of fermentation (which can range from two to several days), the resulting “distiller’s beer” or wash can have different flavour profiles.
At the end of fermentation, the alcoholic strength typically reaches between six and ten percent. Although you wouldn’t serve this liquid at a bar, it contains the base flavours that will later become part of the finished whisky. Longer fermentations often produce more fruity and complex notes, while shorter ones may create a cleaner profile.
5. Distillation: Concentrating the Alcohol
Distillation is where the alcoholic wash is heated, causing the alcohol and certain flavour compounds to vaporize earlier than water. This process enables the distiller to collect the alcohol without all of the water. Most single malt producers use copper pot stills. In the first still, known as the wash still, the heated wash releases vapours that rise and are cooled into a low-strength liquid called low wines, usually around 20 to 25 percent alcohol.
In the second still, known as the spirit still, these low wines are distilled again. This time, the distiller closely monitors and separates the distillation run into three parts: heads, hearts, and tails. The heads can contain harsh or unwanted substances, while the tails hold heavier compounds. Only the middle portion, called the heart, is collected as new make spirit. This spirit usually ranges from around 65 to 70 percent alcohol by volume. Although it is clear and lacks barrel-aged colour, you can already sense some of its core flavours if you taste or smell it, often light cereal notes, fruitiness, or, in the case of peated whiskies, a smoky edge.
6. Maturation: Barrels Work Their Magic
Once the new make spirit is ready, it is placed into wooden barrels to mature. Bourbon casks (often made of American oak) lend sweet, vanilla-like notes, while sherry casks (made of European oak and seasoned with fortified wine) can provide darker, fruitier flavours with hints of nuts and spice. Some distilleries use wine casks that have been specially treated (shaved, toasted, and re-charred, or STR (scraped, toasted and re-charred) casks) to draw out rich fruit layers. Over time, temperature swings cause the spirit to move in and out of the barrel’s wood. This “breathing” process adds colour, smoothness, and complexity to the whisky. The length of aging, as well as the choice of cask, strongly influences the final character.
Whiskies made from corn (like bourbon) must be aged in new, charred oak barrels, which is why bourbon often has that caramel or toffee sweetness. Rye whiskies can also age in charred new oak, creating spicy, robust notes. Some blended whiskies, especially those combining multiple grains, might use a range of casks or finish the spirit in different barrels to achieve a unique flavour profile. Climate matters, too. Warm environments can make the spirit mature faster, while cooler areas allow for a more gradual development.
According to the Scotch Whisky Association whisky from Scotland can only be called whisky when:
“Scotch Whisky must, by law, be distilled and matured in Scotland in oak casks for at least three years and bottled at a minimum alcoholic strength of 40% abv. “
7. Bottling: Bringing Whisky to the Glass
Once the spirit has reached the desired maturity, it is removed from the barrels. Sometimes it is diluted with water to reach the usual bottling strength (often 40% ABV or a bit higher), though some whiskies are released at cask strength. Distilleries may also lightly filter the whisky to remove tiny particles from the barrel. After these steps, the whisky is bottled, labeled, and sealed, ready to be enjoyed by enthusiasts around the world.
Decoding Labels & Choosing Whisky
Learning how whisky is made can make it easier to read labels and choose a bottle that suits your taste. If you see “single malt,” it means the whisky is produced from 100% malted barley at a single distillery. If it says “bourbon,” expect at least 51% corn in the recipe and new, charred oak barrels for aging. Labels mentioning “peated” or “smoky” indicate that peat smoke was used to dry the barley or that the spirit has picked up smoky notes during production. Age statements like “12 Years Old” refer to the minimum amount of time the spirit spent in barrels, although the style of cask and the distiller’s decisions can be just as important as the number of years.
Learn more in our “Guide to exploring different types of whisky”.
Final Thoughts
While every distillery has its own practices and secrets, the main steps remain consistent: prepare and process the grain, ferment it to produce alcohol, distill to concentrate flavours, and finally mature the spirit in wooden barrels to allow deeper flavours to form. Each choice, like the type of grain, the shape of the still, or the kind of barrel, leads to a wide variety of tastes and aromas. By understanding these steps, you can better appreciate the incredible diversity found in whiskies around the world. Whether you prefer the sweet warmth of bourbon, the spicy kick of rye, or the fruity elegance of a well-aged single malt, there’s always more to discover in each glass.
Cheers to exploring the fascinating world of whisky!
For your next read, learn more about craft whisky and distilleries!