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.
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.
"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.
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.
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.
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.