Whisky Shots: The Ingredients Presented by WhiskyCast: Cask Strength Conversation

What's WHISKY?

In the purest of terms, whisky is grain and water transformed by yeast, wood and time.

Whisky is alcohol distilled from a fermented mash of grain which has been aged in oak barrels. It's a simple chemical process that can produce anything from rotgut booze to a subtle and sophisticated spirit. Whether you are curious about whisky or just need a cheat sheet on the basics, scroll to learn more about whisky.

The Grains of Whisky

Whisky is traditionally made using barley, corn, wheat, and rye. Depending on what type of whisky is being made, these four staples of whisky distilling can be combined to help craft different flavors in the end product. Grains are milled to a consistency much coarser than flour but sufficient to break the seed kernels. Barley, if included, may receive special attention with malting and drying. The combination of grains in a whisky is usually a closely held secret within each brand but there are some general taste attributes and mouthfeels associated with each grain.


Barley is known for its nutty and chewy grass flavor in whisky. Malted barley can be spicy, and if dried with peat, can have a smoky, robust flavor.

Barley could be called the universal whisky grain. It is grown globally, and used in most whiskies. It can be malted or unmalted — malting is the process by which barley is mixed with water to begin the germination process of the grain.

Single Malt Whiskies are made strictly from malted barley, but many other whiskies use at least a small amount of barley — either malted or unmalted, to help increase starches in the mash. Unmalted barley is more difficult to ferment so additional enzymes are usually added in countries where it is legal to add them into the mash.


Corn is high in sugars and starches and adds a sweetness to whisky.

The corn used in whisky production is the same used in breakfast cereals and cattle feed — #2 Yellow Dent Corn, not the kind of sweet corn you eat off the ear pictured here. The dent in its kernel gives the corn its name but its ease in drying, high starch content, and widespread availability make it good for whisky production. Other varieties of corn, especially white corn, have been used in whisky production and you see those heritage trends reflected in craft distilling.

Corn is the main ingredient in Bourbons. By law, all Bourbons must contain at least 51 percent corn. As a general practice, corn is also a significant grain in Canadian whiskies.


Wheat produces a smoother, softer, less intense whisky.

Typically, Bourbon producers select between rye and wheat for their mashbill, or recipe. There are two primary varieties of wheat — soft red winter wheat and soft white winter wheat. Both varieties yield pretty much the same result in whiskies, and the selection of one over the other is largely a matter of what is growing in the nearest region.

One of the key factors in selecting wheat over rye for a mashbill is that it matures more quickly than rye-dominant whiskies. Wheat is primarily used in both Bourbons and Irish Whiskies.


Rye grain adds notes of spiciness to a whisky.

While Canadian Whisky is typically thought of as rye whisky, most Canadian distillers use corn as their primary grain and rye as a significant flavoring grain. Bourbons also use rye as a flavoring grain when they want to offset the sweetness of their corn mashbill.

Rye is usually a difficult grain to distill because it can become thick during cooking and can foam during fermentation and distillation. Rye-dominant whiskies take longer to mature but when they do, they are usually thought of as more complex as the spicy notes mellow with time.

Both barley and rye can be malted for use in whisky production.

Malting starts the germination process by mixing the grain with water and keeping the air flowing on the malting floor. While most distillers now use commercial malting houses, there are a few established distilleries who keep the process on-site to allow them to control the level of germination. Sprouted grains have more starch, always a positive factor in whisky production. Once it has begun to sprout, it is then dried, usually in a kiln. Distillers who want a smoky flavor in their whisky will use a peat fire to dry the grain, otherwise the kiln is fueled by natural gas or fuel oil.

While whiskies have been made from just about every grain, the so-called exotic grains can prove challenging. For example, a number of Irish Whiskeys use some percentage of oats. If not watched closely, oats can provide a very sticky, starchy mash which can cause issues with equipment. Though oats have a nice whisky flavor profile, some distillers find them too difficult to use in regular, large-scale production. Other exotic grains which have been used in whisky production include rice, quinoa, triticale, sorghum, millet and spelt.

Water of Life

The word "whisky" is roughly translated from the Gaelic word, "uisge beatha" from the Latin, "aqua vitae," meaning "water of life."
An abundant clean water source is vital to whisky production. Globally, distilleries source water from underground aquifers, fresh water springs, lochs, and processed water supplies. Limited quantities of minerals such as calcium, magnesium and zinc are somewhat desirable for whisky production because they facilitate the fermentation process. Universally, the one element distillers do not want to see in water is iron. Iron does not hold up in the distillation process and can ruin whisky.
Limestone filters iron out of water, which is why distilleries like having water sources near limestone deposits. The PH of water is important to ensure that minerals do not make the water too hard.

Whisky making is a water-intense process. As much as 80 percent of the water a distillery uses does not make it into the whisky. Therefore, there are legal requirements and ethical imperatives for distillers to ensure that used water undergoes reclamation treatment. Distillers have embraced this water sustainability responsibility by developing whisky production initatives which use less water.

Water is also used to adjust the whisky's alcohol strength, or ABV (alcohol by volume), prior to bottling. This water is always filtered and ion-neutral to prevent any additional minerals or chemicals from disrupting the flavor of the spirit.

The Rise of Yeast

Yeast is a living organism, and it takes time to work its magic fermenting the mash. Most whisky distillers use brewers yeast, the same yeast used in for making beer and in commercial baking. There are some distillers, especially makers of Bourbon, who have proprietary strains of yeast and swear that the yeast has a dominant influence on which flavors bloom in the whisky.

The first steps in making beer and whisky are the same: mixing the grains with water, cooking the mash and then adding yeast to begin the fermentation process.
"Whisky is what beer wants to be when it grows up." — Whisky Lore

Mashing is simply the process of measuring and mixing grains and then cooking them. Once the mash has been cooked, all of the starches have been converted to sugars, the perfect food for yeast. The mash is first cooled before it is pumped into a fermentation tank. At that point, the yeast is added and begins to work its magic over several days, making the mash room smell like freshly baked bread.

The mash has been now transformed to wash, also known as distiller's beer. It is between 6 to 10 percent alcohol, and while it could be drunk, it would not be wise to do so because the yeast is still active.

Grains are added to the mash tuns or cookers along with hot water, and then stirred while cooking. A close-up of the bubbling concoction as it ferments shows the yeast cultures feeding on the starches in the brew and transforming them into sugars.

The process of distillation is the same regardless of whether it is producing spirits or gasoline: the base product is heated above its boiling point until the molecules break down into vapors which can be separated from other molecules, refined, and then condensed to form the desired liquid.

Whisky production takes the distiller's beer and does just that — in either a column still or a pot still. The distillation process is different in each of the stills, but the broad strokes are similar. The first run of the distillation produces a high concentration of raw alcohol known as "low wines".

These are diverted off to be re-distilled a second or third time, depending on the specific style of whisky. The stillman — usually a very skilled master craftsman, "cuts" the spirit, knowing when the flow of "high wines" off the still reaches the desired concentrations to ensure a consistent product.

Stainless steel can be used to make a still but copper will still be needed in the process to help with the reactions during distillation.

Early distillers used copper because it was easily formed and durable. Later scientists figured out that copper’s conductivity helped spread the heat source consistently while the metal reacts with sulfur compounds in the ethanol vapors as they rise. The reaction creates copper sulfate, which condenses inside the still and falls back into the wash, leading to a cleaner and better tasting spirit.

The Wood of Whisky

It is impossible to discuss whisky without talking about wood — specifically, oak. American Red Oak has veins which make it unsuitable to hold liquid, but historically it was used to hold dry goods. The two primary types of oak used in whisky production are American White Oak and European Oak. These oak barrels or casks are ideal for maturing whisky because the cell structure of oak allows the whisky to work itself in and out of the wood but also not leak excessively.

Forests and Whisky

One major U.S. cooper makes more than 2500 barrels a day, and the demand for new barrels is expected to keep growing. To ensure a reliable and environmentally sound supply chain, U.S. distillers and cooperages keep tabs on the U.S. Forest Service's Forest Inventory and Analysis report which indicate that American White Oak supplies will not exceed demand until mid-century.

The Different Types of Oak

The two prime types of oak used in whisky production are American White Oak and European Oak, with each type having a distinct flavor impact on the whisky as it matures. American White Oak usually produces a lighter colored spirit and a vanilla flavor in whisky as it matures, while European Oak, which includes the subspecies of French and Spanish oak, tends to produce a richer, darker whisky which has fruitier notes.

Barrels or Casks?

It's about size. Whisky is matured in both barrels and casks, but generally, if you are talking about a barrel, you are talking about an American Standard Barrel which holds about 53 gallons or 195 liters, and more than likely was originally used as a Bourbon barrel.

These are then unassembled and sold to other distillers since the legal requirements for Bourbon include a new charred oak barrel. What makes it interesting is that the staves of three American Standard Barrels can be re-configured to create two hogshead casks, which hold 66 gallons or 250 liters each while using the same amount of warehouse space.

Finishing Casks

While most whiskies mature in one barrel, some whiskies are re-casked for a second maturation in a different cask for up to two years. These finishing casks have previously matured other spirits — frequently, sherry or other types of wine, and are intended to add another layer of complexity to the whisky.

"When you take a sip of bourbon, you are tasting the entire history of an oak tree." — Tom Kimmerer, PhD, Chief Scientist, Venerable Trees, Inc.
Old fashioned coopering meant one craftsman, one barrel. Coopering barrels now is more of an assembly process but still maintains the touch of experience. Barrels prepared for Bourbon are charred on the inside to help filter some of the roughness out of the raw spirits and the heads of the barrels are toasted .

Father Time

There is no chemical process which replaces what time in a cask does for whisky. The magic of whisky occurs in the ebb and flow of the spirit with the wood, and attempts to speed that process fall woefully short.
Distilleries have different philosophies for stacking barrels, controlling heat and humidity, and whether to rotate the barrels within the warehouse, each decision designed to help whisky reach its peak. The one absolute: having air flow around barrels is vital for the safety of the warehouse.

The time whisky spends in a cask is influenced by the humidity, temperature, and altitude — all factors which work to marry the wood and whisky. There will come a point in both reactions where the whisky reaches its peak. Staying too long in a cask could mean that a whisky might become over-oaked. The sweet spot varies for each distillery and changes depending on the age of cask being used and environmental conditions.

Unless it says single cask or single barrel, the barrels selected for bottling are all dumped together and filtered to eliminate any stray pieces of wood char or sediment.

Whisky Wise

We've rounded up answers to some of the most frequently asked questions, and invite you to check out more One Minute Whisky, available on Adobe Spark or on our website.

Whisky is one of those subjects that invites curiosity. The more you know about whisky, the more you want to know about whisky — at least that is our take on the subject.

The Scotch, Whisky, or Bourbon Question...

Whisky: The technical definition of whisky is broad enough to encompass all of the varieties below but international trade agreements and laws within each of the individual countries more specifically define which spirit can carry which name.

Scotch Whisky: The legal requirement for Scotch Whisky is that it be distilled and matured in Scotland for a minimum of three years in oak barrels and bottled at no less than 40 percent ABV.

There are five different types of Scotch Whisky:

  • Single Malt Scotch Whisky: Whisky made from 100 percent malted barley at a single distillery using a pot still; must meet the above requirements and it must be bottled within Scotland.
  • Blended Malt Scotch Whisky: A blend of malt whiskies from more than one distillery; must meet the above requirements and it must be blended in Scotland;
  • Blended Scotch Whisky: Whisky using a blend of grain and malt whiskies from more than one distillery; must meet the above requirements and it must be blended in Scotland;
  • Single Grain Scotch Whisky: Whisky made from cereal grains at a single distillery using either a column still or pot still; must meet the above requirements and must be bottled in Scotland.
  • Blended Grain Scotch Whisky: A blend of grain whiskies from more than one distillery; must meet the above requirements and it must be blended in Scotland.

Irish Whiskey: Both the Republic of Ireland and Northern Ireland may make whisky to be called Irish Whiskey, by international treaty.

There are no requirements for specific grains, nor the type of still used in production, but it must be distilled and aged completely in Ireland/Northern Ireland. The spirit must enter the cask at no more than 94.8 percent ABV; it must be aged at least three years in a wooden cask and be bottled at no less than 40 percent ABV.

Canadian Whisky: Whisky produced entirely in Canada which is matured in wooden barrels not larger than 700 liters for at least three years before being bottled at least 40 percent ABV. Typically, but not by law, Canadian Whisky does contain some amount of rye but the mashbill is not governed; Canada also allows up to 9.09 percent of other spirits, wines or flavorings to be added prior to bottling.

Bourbon: Bourbon is a US spirit with a mashbill at least 51% corn, and after distillation, the spirit can be no stronger than 160 proof; before maturation, distillate must be diluted with water to no more than 125 proof and no flavors or additives can be incorporated prior to maturation. To be classified as Bourbon, spirit must be matured in new charred oak barrels.

There is no minimum aging requirement for Bourbon and it can be made anywhere in the US, however, any Bourbon less than four years old must carry an age statement reflecting the youngest spirit used.

  • Straight Bourbon: It must meet all of the requirements above, with an aging requirement of at least two years in new, charred oak barrels and no additional flavoring of any kind can be added.
  • Tennessee Whiskey: A Bourbon which has been made, matured and bottled in the state of Tennessee.

Currently, there is no international treaty or definition of another type of whisky which has gained popularity, Single Malt Whisky. Single Malt Whisky is almost universally defined by consumers and within the industry as meeting the requirements of a Single Malt Scotch Whisky which is made outside of Scotland.

What's the Best Way to Drink Whisky?

The best way to drink whisky is the way you like to drink whisky.

Whisky is meant to be enjoyed, and with thoughtful savoring, you can discover the many flavors of whisky. To help you with get started on your whisky exploration, here are our recommendations on how whisky is best served:

  • At ambient room temperature and after it has settled from a lot of motion;
  • In a glass which has a bowl to allow the spirit to breathe but a narrow opening so you can smell and capture the aroma;
  • First experience the spirit undiluted as bottled; then if desired, a small amount of room temperature pure water can be added to the spirit;
  • We encourage you to cup your whisky glass and allow the warmth of your hands to help open up the spirit in both scent and taste.
  • Some people enjoy whisky "on the rocks," rather than neat but our experience is that ice usually "closes" a spirit. Additionally, ice can also hold flavors from the freezer or refrigerator that it comes from and may taint the spirit with other flavors as it dilutes the whisky.

Is Older Whisky Better Whisky?

Not necessarily.

Newcomers to whisky generally assume that any whisky with an age statement is automatically better than those without one, a 12-year-old whisky is always better than a 10-year-old, and so on. They quickly learn that this is not always the case. Age statements are an indicator, not a guarantee of quality, but can certainly lead to expectations of a higher price.

Content Credits

First, thank you for sharing your curiosity with us. Whisky can be seriously fun, and we while we never recommend whisky taken by shots, we can recommend shots of information to help you learn about whisky.

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