The whiskey-making process is long, tedious, and precise. It’s a process that varies slightly by region, but each distillery passes down its secrets from family to family, generation after generation, refining their techniques over time while preserving traditions. From growing the ingredients to shipping out a matured bottle, the entire process can take a couple of years or decades. This post will explore the ingredients used to make whiskey and the manufacturing process from malting to bottling. 

Ingredients Used in Making Whiskey

The ingredients used in making a bottle of whiskey are just as essential as the barrels it’s aged in. Whiskey comprises three main ingredients: water, barley (or other grains), and yeast. Using a pure filtered water source is of primary importance in the whiskey-making process; impurities or minerals like iron can change the taste of the final product, which is why a lot of distilleries operate near quality water sources such as rivers, wells, or lakes. Whiskey yeast is the critical component in fermentation that helps to convert the sugars into alcohol before distillation. Each of these ingredients works together to create a magical concoction ready for its manufacturing process. But how does each of them make the aromas and flavors we love? Let’s look at the roles and characteristics of each ingredient a little more closely.

Water

While you might think the grains are the most essential ingredients in whiskey, it’s the water that determines the quality of a whiskey bottle. The word “whiskey” comes from the Gaelic word “uisge,” which means “water,” which highlights its importance right away. The water used in the whiskey-making process must be clean and free of impurities that can alter the taste. Areas like Kentucky, Maryland, Pennsylvania are rich with limestone, so the water contains carbonates, which can change the flavor. Scotland, known for making the world’s finest whisky, has some of the purest, best-tasting water sources globally. It’s common for a whiskey distillery to be located near a natural body of water or a pure water source, such as a lake, a well, or a river. 

Grains

All whiskeys begin with a combination of grains called a “mash bill.” The types and amounts of grains used determines the type of whiskey being made, but all whiskey requires some malted barley to ferment the spirit. Besides barley, most whiskeys are made with a blend or “mash bill” of other grains such as corn, rye, or wheat, which creates texture and depth. 

Barley

Barley is the most essential grain for whiskey’s fermentation process. Barley must be malted, which is a lengthy controlled process for germinating grains. The purpose is to activate the enzymes that break down the starches and convert them into sugars, which is then fermented by the yeast, and nearly all whiskeys depend on this process. Not all barley is created equal. The best barley to use has low nitrogen content or high starch content, and an easy ability to germinate and malt. 

barley, whiskey grains

Here are some of the other most important factors.  

  • Vitality
  • Consistency of size, shape, and color
  • Condition, appearance- free of damage from weather, fungi, or pests
  • High nitrogen content
  • No contamination from other seeds

Corn

Corn helps to accentuate sweeter flavors of whiskey like honey, vanilla, and maple syrup, making this an easy drink to sip on. While corn is often credited for the sweetness, no grain provides sugar content because it doesn’t pass through distillation. The sweet vanilla flavors come from aging the spirit in oak barrels. The longer bourbon whiskey is aged, the deeper the flavors develop, including notes of roasted marshmallows, and an earthy, leathery finish. 

Rye

Rye creates an intense peppery, spicey sipping experience. The higher the rye content, the more intense the flavors develop. If a whiskey’s mash bill has at least 51% rye, it’s classified as a bourbon- a dry, sharp spirit that packs some serious heat. Not as sweet as corn whiskey, rye yields rich nutty and spicy flavors such as nutmeg and cloves, making the whiskey unique. 

rye, whiskey grains

Wheat

Wheat yields a sweeter whiskey with a relatively low spice factor. Similar to corn, it doesn’t offer a sweet sugar content to the spirit. Still, because it’s not a vital flavor source, there’s plenty of room for the oak barrels to work their magic and bring out sweet flavors and aromas like honey, vanilla, dried berries, spice, and toffee flavors. It yields a smooth, light whiskey that’s easy and enjoyable to sip. 

Other non-traditional grains

Some distilleries make their whiskey with other less popular grains, such as millet, oats, rice, or triticale (a hybrid of wheat and rye). These are used to accent major grains that we mentioned above, creating flavor complexities. Millet offers licorice or anise notes; oak makes a creamy, dense body; rice adds nutty flavors with an oily texture; triticale tends to yield tastes similar to breakfast cereals. There’s plenty of room for experimenting with flavors and combinations, which makes whiskey-tasting super interesting. 

whiskey grains, non-traditional grains

Yeast

Yeast is the key ingredient used in the fermentation to convert the sugars into alcohol. Some distilleries even keep a mother yeast culture and propagate them on an ongoing basis. There are different types of yeast, depending on the whiskey being made, but as long as it converts starches into sugars, any yeast can be used. Some options include dried or creamed yeast, traditional American ale yeasts, brewer’s yeast, or even Champagne yeast.  

How to Make Whiskey- the Manufacturing Process

Malting

Malting is a precise, lengthy process during which barley grains are germinated for fermentation. First, the barley is sourced, and then it’s cleaned. Next, it’s stepped in water inside large tanks between 48 and 72 hours to begin the germination process. This time is split between steeping and aeration periods, depending on what’s required for the finished malt. Submersions and cycles of air rest periods vary between 8 and 12 hours. 

Once the grains begin to “chit” or rupture, it’s spread out in a particular room where the temperature and humidity are precisely controlled to allow the grains to germinate and sprout.  A rake is used to turn the material, keep it from drying out, and allow fresh air and carbon dioxide in. Once the grains sprout, the germination needs to be halted so that the enzymes responsible for converting the starches into sugars can be utilized. 

malting grains for whiskey

While some may understand that heating the grains stops the germination process, it’s actually draining the water and drying the barley that prevents the germination. Draining, drying, and cooking are all little stages in the next big cooking step, which takes place inside a massive kiln. During this step is where distillers can develop flavors and colors through various means such as steaming, recirculating air back through, or increasing and decreasing times and temperatures in the kiln. 

After about 24 hours, the grains are moved to an auger, where the rootlets are knocked off, and then cleaned, sorted, and separated. Once the grains have passed through sampling and out, it’s toasted, bagged, sent to brewers and distillers who use it to make delicious whiskeys, beers, and more. This entire malting process can take up to three weeks. 

Mashing

Mashing is the brewer’s term for the hot water steeping process during which the barley is heated to activate the malt enzymes, converting the grain’s starches into fermentable sugars. The heated water breaks through the grains’ walls, seeping into the starch granules, which then activates and gelatinizes them. After a few hours of mashing, a thick, sugar-rich liquid forms, known as “mash.” At this point, enzymes such as amylase, amylopectin, and a secondary enzyme dextrinase are necessary for converting the gelatinized starches into sugars. 

The grain is placed in insulated circular mashing tuns that can hold 4 to 12 tons of grains and 40,000 to 120,000 liters of hot water. The grain is mixed by giant rotating arms that spin around, keeping the grains “fluffed” and ensuring water circulates through the entire bed.

mashing whiskey

Different grains require different temperatures to gelatinize correctly, but generally, barley and the amylase enzyme temperature is about the same, while gelatinizing corn starch requires a significantly higher temperature. The high temperatures also help sterilize the grain, and once the grain has gone through the mashing process, it can be sold to farmers as highly-nutritious, high-protein cattle feed.

Another important factor in the mashing process is the pH or the acidity of the liquid. The pH affects the shape of the enzymes that we’re working with, so if the pH isn’t within a suitable range, the amylases and secondary enzymes won’t function and may not convert into sugar. The preferred pH range for mashing is 5.2–5.8, with 5.4 considered optimal. 

How much time does it take to convert the starches into sugar? This depends on a few factors like the ingredients and thickness of the mash, temperature, pH, and any modifications taking place in the process. TIME??

Now it’s time for the mash to be drained. After the batch of water is drained, more hot water is added to extract more sugars. The soaking and draining process or the “wash” is repeated three or four times, each time increasing the water’s temperature being poured in, to entice the starch granules to open. Each wash takes between 4 and 6 hours. The sugary liquid removed from the mash is called the “wort” which will rest and cool, and then be fermented in the next step. Until then, it can be stored in malt silos for 4 to 12 weeks.

Fermenting

The “wort” or thick sugary liquid will be transferred into large fermentation vessels called “washbacks” to begin the fermenting process. Traditionally, wooden washbacks were used, but due to cleanliness issues, many of them have been replaced by either cast iron or stainless steel washbacks. Yeast is added to the wort, which converts the sugars into alcohol in a beer-like substance called “wash.” If you taste the liquid during fermentation, it’s very sweet, and it tastes similar to breakfast cereal. Fermentation takes about 48 hours, but distilleries may choose to ferment their liquid longer to create different flavor characteristics. 

Contrary to what many believe, yeast is fungi, not bacteria. Different kinds of yeasts can be used, like whiskey yeast or brewer’s yeast. Still, many distilleries use a blend of both types, which ensures a quick and thorough fermentation while creating desirable aromas and minimizing foam development.  

While you may be able to smell alcohol during fermentation, we wouldn’t recommend putting your nose too close to the washback because fermentation creates a byproduct- carbon dioxide. This causes the bubbles and the foam and then evaporates into the air (unless a distillery uses a closed washback). 

fermenting whiskey

When there is no sugar left for the yeast to transform, this is the end of the primary fermentation; but now an interesting reaction occurs. Bacteria inhabiting the malt since before the mashing process begins to work. These bacteria include acids, aldehydes, esters, and long-chain alcohols. The chemical reactions create new compounds, influencing the aroma and the body of the wash.

After fermentation, the mash will end up with an alcohol concentration of about 6 to 10%. This is sufficient for beer, but it will need to be distilled in the next step for a whiskey. 

Distilling

Distilling is removing the alcohol from the “wash,” which is the product finished with the fermentation process. During this process, the concentrated liquid is poured into “stills” heated with steam, evaporated, and re-liquified. It usually needs to be distilled twice to control the alcohol by volume (ABV), but Scotch Whisky is traditionally distilled three times. Distillation is done in either a pot still or a column still. 

Types of Distilling: Pot Still

Pot stills are like oversized kettles. They’re heated from the bottom until the alcohol boils and evaporates. The evaporated vapor is separated into another container called a condenser, through the still’s long neck. Here, cold water is continuously running, which transforms the vapor back into a liquid. 

pot still

Types of Distillation: Column Still

In a column still, the wash enters near the top and trickles down a series of plates steamed from underneath. This steam heats the alcohol, causing it to evaporate and then rise back up through the heated plates. Because the liquid is in a constant state of rapidly heating, evaporating, and re-liquifying, some of the heavier compounds are removed and left behind. In comparison, the lighter compounds make their way up the column, thereby purifying and refining the liquid.

column still

Hybrid Still 

Many of the United States’ distilleries use a hybrid still, which is a pot still at its base but also has one or more columns, which allows a distillery to produce different types of spirits and control or customize distillation as it’s made. 

The Difference

The main difference between pot and column stills is that pot stills operate on a batch by batch basis, and column stills can be operated continuously. A column still or a “continuous still” can also produce spirit over 95% ABV, whereas pot stills cannot reach this level. Most pot stills are made of copper, and column stills are partially stainless steel. Only the upper portion of the column still is made of copper, which is essential because it’s used to rid the spirit of sulfur. 

Besides differences between types, there are also differences among stills of the same type: the size or capacity, the temperatures, the length and angle of the necks, and the style or position of the heating sources. In the case of pot stills, the shapes of the kettles can vary. And in the case of column stills, the number of plates and height of the columns vary. 

Heads, Tails, and Hearts

During the heating period of distillation, there are various unwanted components that must be eliminated. This is done by separating the distillate into three parts according to its components and quality- the “head,” the “tail,” and the “heart.” The heart is the drinkable part of the distillate with the flavors and ethanol that will be kept and ultimately used in the final product, while the head and the tail of the distillate must be removed. The head is the first part of the distilled liquid, and it contains toxic methyl alcohol as well as substances that would give the spirit an unpleasant sour taste. The tail is the last part of the distillate which will also be eliminated because it contains unpleasant fatty and oily substances. It will either be disposed of or redistilled to collect more alcohol.

Heating

The traditional heating method stills was through the direct flame from wood, coal, or burning fire underneath, but this is also a risky and messy process. Now, stills are more often heated through steam piped through coils underneath or at the base of the still. Whiskey is usually distilled twice to rid the spirit of contaminates and ensure a pure product. It’s then cooled and ready to be aged or matured. 

Aging

Aging whiskeys is the process of maturing distilled spirits in wooden barrels to remove harsh flavors while absorbing flavor characteristics of the barrel’s wood. Barrels or casks are usually made of American, Spanish, or French oak because it holds liquid without leaking, and the porous quality of oak adds flavor to the whiskey. Some of the casks are previously-used, and a lot of them are charred for smokey flavors. It’s possible to use casks made of other wood types, giving way to a broader range of flavor profiles. 

whiskey casks

Whiskey matures for at least two years, but many whiskeys are aged for 10 or 15 years. During each year of aging, around 2% of the spirit evaporates, which means the longer a whiskey is matured, the less liquid is left in the cask when it comes time to bottle. This is one reason why older whiskeys are harder to find and are more expensive. 

Bottling

Now that the whiskey has been manufactured from grain to maturation, it’s time for the bottling process- the final manufacturing stage. At cask strength, whiskey sits at around 60% ABV; it can either be bottled at Cask Strength or cut with purified water and reduced to about 40% ABV, which is the legal minimum that whiskey must meet to be sold. Some whiskeys are also chill-filtered before they’re bottled, which filters out any flock that may cloud whiskey when it becomes too cold. Each of these processes is carried out depending on the brand’s preferences the spirit was created for. Most packaging will tell you if whiskey is bottled at Cask Strength or is chill-filtered, though most brands choose against chill-filtering. Whiskey is always bottled in glass because glass does not alter or affect the whiskey’s flavor at all. 

whiskey bottling

What’s next?

After the bottling stage, this fantastic spirit is shipped out to be sipped and enjoyed by novice and expert whiskey drinkers worldwide. At Taster’s Club, we build relationships with distilleries and brands, allowing us to curate unique whiskey bottles for our whiskey club members each month. Ready to be a part of our Whiskey Club?