Why Is Bourbon Aged in a Barrel?

To people not versed in the particulars of bourbon whiskey, it may appear as if there are many seemingly arbitrary rules. Does bourbon really need to be produced in the state of Kentucky to officially be bourbon? Is it necessary to age it in a bourbon barrel? The fact is, to create the distinct flavor of bourbon that you know and love, there are a few steps that distillers must take. And, yes, there are a few rules that dictate what is and is not bourbon.

These rules aren’t arbitrary, however; each of them is in place for a reason. For example, bourbon just wouldn’t be bourbon if it wasn’t aged just so in a barrel. Below, we’ll explain why that is and how it affects the taste profile of one of our favorite beverages.

What Makes Bourbon… Bourbon?

Bourbon is a type of whiskey, meaning that it’s made from fermented grain mash. All bourbon is whiskey, but not all whiskey is bourbon. Other types of whiskey include Scotch, rye whiskey, and blended whiskey, among others. The differences between the varieties of whiskey include both the region where distilled, ingredients, and the method of distillation.


For example, Scotch is generally—but doesn’t necessarily have to be—produced from malted barley. Bourbon, on the other hand, is primarily created from corn mash. Actually, to be legally considered bourbon, the drink must be produced from at least 51% corn, although other ingredients may also be used. This difference in ingredients is the first thing that has a major effect on the flavor of the whiskey.


Region matters as well. Scotch, of course, is produced in Scotland. Other countries can produce a similar beverage using the exact same ingredients and techniques, but it isn’t technically Scotch unless it’s produced in Scotland. The same applies to bourbon. While it doesn’t need to be produced in Kentucky, the law does require it is distilled in the United States. However, approximately 95% of bourbon is produced in Kentucky, and the beverage does originate from there. Indeed, it’s popularly believed that the name bourbon comes from the area of Old Bourbon in Kentucky.


The method of production is also key to the production of bourbon. It’s not enough for it to be produced from corn mash in the United States. There are plenty of other beverages that are created in this way. To be bourbon, it must be aged in a bourbon barrel. A bourbon barrel must be a new, charred oak container. Other whiskeys frequently utilize used barrels, but to be bourbon, the barrel must be new. However, many bourbons are moved into other barrels to be finished after the aging process is complete.

There is no rule regarding how long a bourbon must be aged. Some are aged for many years, while others may remain in their barrels for only a few months. It is required, however, for bourbon aged less than four years to sport an age statement upon its label.

Finally, bourbon must be distilled to 160 proof—that’s 80% alcohol—and not more. It must be bottled at a minimum of 80 proof, or 40% alcohol.

What Does It Mean to Age Bourbon?

We’ve mentioned several times the legal requirements for aging bourbon in a barrel. But what exactly does this mean? And what processes are taking place when the bourbon is aging in a bourbon barrel?

Most bourbon barrels have a volume of 53 gallons, although this isn’t a requirement. What is required, however, is that the barrel is charred on the inside. To char a barrel, flames are shot through it for a certain amount of time. The majority of distillers use what’s known as a number 4 char—that is, the barrel has been toasted for about 55 seconds—but other numbers are also allowed. As the flames lick the sides of the barrel, they cause the sugars in the woods to caramelize. As the bourbon is aged, these caramelized sugars will impart their distinct toffee taste to the distilled alcohol, helping to create the unique flavor bourbon is known for.

When alcoholic beverages are initially distilled, they tend to be of a very strong proof and with very little in the way of flavor, other than an alcoholic bitterness. They are usually clear, much like vodka. The aging process helps to mellow out the harshness of the alcohol while also lending the bourbon its distinctive flavor. The flavor notes are drawn from the wood itself; the longer the bourbon sits in the barrel, the more rich and complex its flavor profile will be. However, there’s a limit to this. The federal standards regulating bourbon state that it cannot be aged more than 25 years. Indeed, if it’s aged over 15 years, it tends to lose some of its flavor complexity and take on a bitter taste.

Because bourbon is required to be aged in new barrels, bourbon barrels cannot be reused (at least, not for making more bourbon). In many cases, used bourbon barrels can be utilized to make other types of alcoholic beverages. That’s why you’ll sometimes see “aged in a bourbon barrel” printed on the label of other types of alcohol.

Where Can I Try All These Aged Bourbons?

While the laws governing the creation of bourbon are fairly strict, they allow enough freedom for distillers to create many different variations of this famous drink. Different recipes, different batches, different barrels, different char levels, and different aging times all play a role in the finished product.

If you want to get the chance to sample as many of these wonderful bourbons as possible, you will need to find a great bourbon bar with an extensive menu. Bourbon & Bones in Arizona is an excellent example of such a bar. With an exhaustive menu with dozens of options, you’ll be able to visit over and over again without ever becoming bored with the selection. Even better, it’s also a steakhouse, so you’ll be able to enjoy the perfect food pairing with your perfectly aged bourbon.

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