A Deep Dive into The Process of Making Whisky

Ever wondered exactly how your favorite whiskey is made? Well, that's the topic for today's post! But not your favorite whisky per se (otherwise, we would have to write a thousand articles) but whisky in general. You see, making whisky from start to finish follows a defined number of steps:

  1. Grain Selection & Preparation of Substrate
  2. Malting
  3. Mashing
  4. Fermentation
  5. Distillation
  6. Aging
  7. Bottling 
  8. Bonus: Blending

It's important to point out that not all whiskies follow only these 7 stages. Some have simpler processes with few steps, while other whiskies are more complex and require a myriad of extra steps added somewhere along the way. Nevertheless, this should give you a good idea of the general whisky-making process. 

Whether it's multi-billion dollar plants like The Jack Daniel's Distillery and Crown Royal's Gimli Distillery or smaller establishments such as family-owned/ independently owned distilleries, the process of making whisky shares many similarities.

Let's get started!

1. Grain Selection & Preparation of Substrate

Each whisky starts with just three ingredients: water, grain base, and yeast.

The main grains used in whisky-making are corn, rye, barley, and/or wheat grain. These grains—along with the oak barrels they're aged in — define the final taste and aroma of the spirit. This is why most whiskies are made with a blend of these grains to create texture and depth and fully bring out the best flavor of each grain. 

The soil and conditions that the grains are grown under, influence their overall mineral content and flavor. This, in turn, impacts the final whisky aroma profile. Although not all distilleries can grow their own grains, the ones that do, ensure they oversee the entire process. 

  • Malted barley produces a smoky, toasted, or nutty flavor
  • Rye produces spicy flavor notes.
  • Wheat typically provides notes of honey, vanilla or mint and it used to create a softer or more gentle whisky
  • Corn offers sweet vanilla and buttered popcorn flavors.

 This is why each distillery has its own recipe for the grain mixture. Whisky can vary wildly in taste, tone, color, and everything else, simply by changing the combination of grains used.

All grains, except for barley, are ground into fine flour in a gristmill. The grain meal is mixed with water and cooked to break down the cellulose walls that contain starch granules. 

However, the water needs to be clean, clear, and free of bad-tasting impurities like iron. That’s why the most famous distilleries are often located near a river or lake in areas rich in limestone deposits. 

Limestone imbues the water with essential minerals that are consumed by the yeast during the fermentation process. Second, it filters the water and removes iron, which might discolor the whiskey and turn it black during the aging process. 

whiskey grains

2. Malting

Malting barley involves soaking it in water until it's saturated. It then gets spread out and sprinkled with water for about three weeks until it begins to sprout. 

Germination produces an enzyme called amylase, which is responsible for converting the barley into sugars. So the purpose of the malting is to release enzymes that break down the starches in the grain and help convert them into sugars. 

The next step involves drying the barley with hot air from a kiln. The malted barley is then ground like other grains.

These days, most distilleries outsource the malting to dedicated maltsters who use modern-day mechanics to carry out this task. Malting plants receive truckloads of barley every day, process it, then send out the malted barley to the whiskey distillers.

malted barley

3. Mashing

Most whiskies (like bourbon and rye) have precise guidelines for their mash bills. The exact grains used and their percentage depend on the type of whisky being made.

For example,

  • Bourbon must contain at least 51 percent corn base.
  • Straight rye whiskey must be made from at least 51 percent rye grain.
  • Malt whisky is always made using 100% malted barley.

The sugars contained in the grain must be extracted before fermentation, and this is done through mashing. The next step is to mix the cooked grain with malted barley and hot water.

The effect of the hot water is to induce the natural enzymes (amylase) to break down the starch in the grain into fermentable sugars. 

Achieving an accurate balance of temperature is crucial, as a temperature above 65.5ºC can potentially damage or destroy enzymes within the barley.

After several hours of mashing, you end up with a thick, sugar-rich porridge-like liquid known as “wort” ready for fermentation. The wort is separated from the mash by sparging, which means flushing hot water through the mash and then draining it off through the perforated floor to collect all the sugar.

This is usually done several times using different water at different temperatures. 

The remaining husks are sent for processing into draff: a by-product that's often used to make nutritious cattle feed.

4. Fermentation

As yeast can't stand hot temperatures, the wort is cooled down to about 20°C. Once the mash has cooled, it's transferred into large tanks (or fermentation washbacks) to begin the fermenting process.

Traditionally these washbacks are made with Oregon pine wood, but some facilities have transitioned to stainless steel.  

The main difference between the two is this: steel is more easily cleaned and requires less maintenance, while wood harbors certain bacteria that would otherwise influence the flavor creation. At the end of the day, it really comes down to the distiller preference.

Yeast is added to the wort and gobbles up all the sugars in the liquid and converts it to alcohol. The yeast then transforms some of the alcohol into flavor compounds, like esters, which impact the whisky's flavors. 

Different kinds of yeast are used by distillers, but they all belong to a species called "Saccharomyces cerevisiae." This yeast strain ensures a quick and entire fermentation, creates positive aromas, and minimizes foam development.

Fermentation usually takes about 48 hours. However, some distilleries will let it go longer to create different taste characteristics. The result is a liquid—called distiller's beer or wash and is generally 7%-10% ABV before it goes into the still.

5. Distillation 

As the yeast eats up the sugars during fermentation, they create alcohol and CO2. But the more alcohol and CO2 they produce, the less sugar there is for them to feed on.

And at a certain point (around 14 to 18% ABV), the alcohol levels become toxic for the yeast. To get high ABV alcohol, you have to separate alcohol from water using evaporation and condensation. This process is known as distillation.

Because alcohol has a lower boiling point than water (173 F vs. 212 F), distillers can evaporate the alcohol alone, collect the vapors into a tube and use cold temperatures to force the alcohol to condense back into liquid. 

In all of whiskey making history, just two methods of distilling have been created.

Depending on what's being distilled, there might be tall gleaming columns connected by a network of tubes referred to as column stills or massive, squat pots known as pot stills. Pot distilling has been around for centuries, while column distilling is relatively new, only having started being used in the 19th century.

Column stills allow continuous distillation, meaning they're capable of drastically higher production than pot stills, which require cleaning after each batch. Spirits distilled in pots top out between 60 and 80 percent ABV (after multiple distillations). At the same time, columns can reach an ABV of up to 96 percent.

Many distilleries today use what's essentially a hybrid pot still. It has a pot still at its base and one or more columns, allowing a distillery the flexibility to produce different types of spirits and control the specifics of distillation along the way.

Distillers have embraced technology and at large facilities, stills are typically computer-controlled and monitored for better efficiency and production speed.

whiskey pot stills

6. Maturation/Aging

Whiskey is then aged in wooden barrels, typically made from charred white oak. White oak is the preferred wood because it can hold a liquid without leaking, and it also allows the water to move back and forth within the pores of the wood.

The congeners, esters, sugars, and alcohols react together, adding distinct flavors and aromas to the whiskey. Maturation for whiskey takes at least two to four years, but many whiskeys are aged for 10, 15 or even more years.

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American whiskeys are generally aged in warmer, drier conditions, so they lose water which increases the alcohol content. Scotch whiskies are aged in cool, wet conditions, so they absorb water and become less alcoholic.

Once again, water is a key ingredient in the whiskey production process. After the distillation is done, water is added to reduce the alcohol content down to either 50-60 percent for American whiskeys or 65 percent or higher for Scotch whiskies. This is done to try and compensate for the environmental impact.

Yet sometimes, this is not enough. During each year of maturation, about 2 percent of the spirit is lost as a result of natural evaporation.

This phenomenon is known as the "angel's share" and explains why older whiskeys are less common and much more expensive to buy: there's less whiskey in the cask to bottle.

whisky maturation

7. Bottling

This is the final stage in the process. The master distiller samples different barrels to get an indication of the quality and character of the contents. If he/she feels the whiskey is ready for bottling, the selected barrels are brought to the bottling line and emptied over filters.

The charcoal pieces that broke away from the barrel walls during maturation are held back by the sieve. The alcohol level of cask strength whisky is usually around 60% and needs to be diluted to meet the recommended ABV. 

The standard of whisky alcohol percentage stands at 40% ABV or 80 proof. To achieve this, purified water is added to the whisky. Then the whisky is pumped into a storage vat and from there fed into the bottles.

Some whisky enthusiasts get around this standard ABV requirement by buying cask strength whisky and diluting it themselves.

Whisky is bottled in a variety of bottle sizes, shapes, and materials (all dependent on the particular brand). Typical sizes are 0.2 litres (flat bottle), 0.7 litres (Europe), 0.75 litres (US market, Japan), 1.0 litres (duty-free) and 1.89 litres (half-gallon).

Bonus Point: Blending

The majority of whiskies from Canada are blended as well as most Scotch Whisky brands. 

Yet, blending whisky is a considerable art acquired only after years of experience and experimentation. This is because often, a blend will consist of anything from 15 to 50 different single whiskies, combined in the proportions of secret and well-guarded formulas. 

The most important thing is to produce a whisky of a definite and recognizable character. This is often the work of a master blender who, above all, needs to have a fantastic sense of smell and be able to describe and identify those smells.

Without this, it becomes very difficult to create and recreate quality blends consistently.

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