What is whisky?
Whisky, or whisk(e)y as the Irish and Americans spell it, is a potent, distilled alcoholic beverage that’s enjoyed by many across the globe. Whisky is arguably the most complex spirit and boasts of over 100 aromas and flavours, commonly known as the whisky notes.
Who would’ve guessed that this remarkably complex liquor is made from just three basic ingredients: grain, water, and yeast. Well, four, if we could count wood as one.
The different types of whisky come from the fermentation of different grains. Scotches are mostly made from barley while American whiskeys, like the good ol’ bourbon, use other cereals such as corn, rye, and wheat.
Of course, the process of making whisky plays an equally big role in the final taste. As they say, one can have all the ingredients but it takes a good chef to make a tasty meal. For whisky, it takes a good distillery.
How is whisky made?
The ingredients may be simple but the whisky-making process is far from it. Hours, days, and years are dedicated to the creation of this majestic spirit. Whisky-making, if broken down to a single phrase, is the science and art of converting starch into sugar. Intrigued? Let’s get right into it.
Step 1: Malting
All whisky starts with malting—a process of turning raw grains into fermentable sugars with four important steps.
As the title suggests, the first step to making whisky is to soak the harvested grains in large vats of heated water. The water is usually changed two to three times and the immersion can take up to three days. Some distilleries pump in oxygen to quicken the process, making it easier for the grains to absorb the water.
Why soak the grains in hot water? Distillers do it to kickstart the germination process. The warmth from the water gives the grains an illusion that it’s the season to germinate. Without germination, there is no whisky.
In case you’re wondering, the grains are not left to sprout in the water. They are laid out neatly on malting floors to dry and germinate. Here, the grains release growth hormones that naturally assist the production of two important enzymes: the alpha and beta amylases which will later convert starch into sugar.
The germination period can take up to nine days, during which, the grains are raked regularly to evenly distribute the heat released from germination, and to keep the grains cool.
How mother nature works is indeed a curious thing. Heat from the water is used to induce germination while heat from the kiln is used to stop it.
Once the sprout reaches three-quarters of the seed, these semi-mature grains are gathered and laid out in another room; this time, above a kiln—a large furnace for heating, cooking, or burning.
When the hot air from the kiln rises up, it dries the grains, halts the germination, and eliminates any bacteria surrounding it. We now have malted grains with a malty, cereal sweetness. If peat is used as fuel for the kiln, then the whisky will inherit the peat’s smoky taste.
In the final step of the malting process, the dried grains enter a mill where they are crushed or sifted to remove the chaff. All that is left is the grist—the part of the seed where the alcoholic sugar is extracted from.
Another trip around the mill grounds the grist into a desired consistency. This allows for maximum extraction of the sugar in the later stages. Lo and behold, the malt is finally ready for mashing.
Step 2: Mashing
Photo by Glenfiddich Distillery.
Mashing is where the starch magically turns into sugar. The milled grist, or malt, is steeped into hot water in a large container known as the mash tun. This step is done three times in total and at varying temperatures, starting at 65°C, then again at 75°C, and lastly at 80°C. In each of those rounds, the malt is stirred with a gigantic rotating tool that resembles a garden rake.
Malted barley may be added as a catalyst to speed up the conversion of starch to sugar. At the end of the mashing, we now have what is called a mash or a wort.
Step 3: Fermentation
We’ve used grains, we’ve used water—what about the yeast? Aha! The yeast is added during fermentation, after the wort is poured into a fermentation tub called the washback.
Like a hungry beast, the yeast eats away at the sugar, turns the sugar into alcohol, and releases carbon dioxide in the process. It will take the yeast two to four days to gobble up the entire tub of wort. The result is a mush of beer-like wash pertaining 6–11% ABV.
Perhaps it is worth noting that different strains of yeast can result in different whisky flavours, so picking the right type of yeast is just as imperative as picking the type of grain.
Step 4: Distillation
We’ve reached the crux of how whisky is made. Distillation, the process of separating water from ethanol, is what differentiates whisky from beer. Ethanol evaporates at 78.3°C while water, as we know it, turns into steam at 100°C. Since ethanol is more volatile than water, distillers are able to collect the alcohol for consumption and leave the water behind.
Labels such as ‘triple-distilled’ beg us to wonder just how many times the wash undergoes distillation. The common practice is two times to achieve an alcohol percentage of 40%; three times for a much higher concentration.
There are two types of distillations: pot still distillation and column still distillation. Both are made from copper for good reasons. Firstly, copper is an excellent heat conductor, which significantly reduces the time needed to boil the wash. Secondly, and more importantly, copper helps clear away unpleasant flavours and aromas such as the pungent smell of sulphur.
Now that we’ve covered the basics, let’s deep dive into how each type of distillation works and what it achieves.
Pot Still Distillation
Photo by The Macallan.
Most commonly used by the Scots in crafting their famous malt scotches, pot still distillation produces whisky in batches.
The pot still is made up of three parts: the bulbous kettle—where wash boils, the gooseneck—a curved vessel where the purified alcohol vapour travels, and the cooler—where the vapour condenses into colourless liquid that distilleries call new make whisky.
In the first run of distillation, the wash goes into the wash still and produces the low wine—a weak liquor of only 20% ABV. On the second run, the low wines enter the spirit still and pumps out whisky at 40% ABV. From here, the distillers have a choice of either collecting the double-distilled whisky in a spirit safe or distil it for a third time to achieve 60% to 70% ABV.
Column Still Distillation
Photo by Old Forester.
If the Scots fancy the pot still, then it must be the Americans who prefer the column still. If that’s your guess, you are absolutely right! Bourbons and many American whiskeys are the result of column still distillation.
What’s not to like? It works continuously and simultaneously, so it’s mighty efficient, and it’s capable of producing a spirit up to 95.6% ABV. If the Americans like their coffee strong, they sure like their whiskey stronger.
Funnily enough, it was an Irishman by the name of Aeneas Coffey who patented the column distillation. Maybe that’s why the Americans took on the Irish ‘e’ in spelling whiskey. Thanks to Mr Coffey, column stills are now better known as Coffey stills.
To make whisky using a Coffey still, distillers put the mash at the top and let it descend through layers of perforated plates. A strong blast of hot steam rises from the bottom and removes the heavier unwanted substances from the wash while sending the lighter alcohol vapour to the top. This creates a constant stream of low wines (20–25%ABV), and the cycle repeats until a desired alcohol percentage is achieved.
Each plate is slightly cooler as it reaches the top, so the condensation rate differs at each level with the lighter compounds such as ethanol reaching the higher plates before it condenses. The heavier compounds such as diesel and congeners stay at the bottom. In other words, the purer the vapour, the closer it gets to whisky nirvana before being stored into oak casks.
Step 5: Maturation
Unlike wine, whisky doesn’t age in bottles, but in oak casks. The age of the whisky refers to the time between distillation and bottling. Some types of whisky require a minimum age by law. Scotch needs to be barrel aged for a minimum of three years before it can be classified as a Scotch whisky.
The maturation in oak casks affects about 60% of the whisky profile, or more. That’s because the spirit chemically reacts with the wood to acquire its flavours. There is a longstanding myth that says the longer the maturation, the better, but that isn’t always true. Older whiskies may be classified as rare and have a higher value, but there’s so much to consider from the types of wood used before we can determine if the whisky is good.
Since whisky actively interacts with the wood, about 1–2% of the alcohol evaporates in the process, causing the warehouse to smell like whisky. The evaporated alcohol is called the angel’s share. There is a running joke in the whisky community about this: distilleries pay two types of tax—one to the government and the other to the spirit angel.
Step 6: Bottling
The final step before it reaches our hands. After maturation, distillers can choose to blend the whiskies, chill-filter them , or bottle them straight from the cask. Chill-filtering removes the fatty acids and prevents the whisky from clouding when met with cold water or ice. Most distilleries do this, and when they don’t, it is specified on the bottle.
Once the whisky is bottled, it is labelled according to its age and type. When the bottle contains whisky from only one barrel, it is labelled as a single barrel whisky.
There you have it—the entire whisky-making process laid out step by step. We hope this makes you appreciate the divine spirit even better. While we can’t cross borders to visit distilleries just yet, we can always enjoy flights of their most respected expressions by signing up for your very own whisky-tasting adventure at home.