What Is Bourbon Whiskey?

Whiskey Barrel Wagon at Maker's Mark Bourbon Whiskey Distillery
Shannon Graham

Bourbon whiskey is America's native spirit and is one of the most popular styles of whiskey today. It is also one of the most controlled and regulated distilled spirits and in order to begin to fully appreciate bourbon, it is important to know the how it is produced manufacture and how that relates to the end product in your glass.

Bourbon must be made from at least 51% corn mash.

Corn contributes a noticeable sweetness to the final product and often makes up a much larger percentage of the mash bill in a bourbon whiskey. Other grains used to round out the mash bill include rye, barley, and wheat.

Bourbon must be a product of the United States.

Some people think that bourbon can only be produced in Kentucky, but that is erroneous. While the vast majority of bourbon is made in Kentucky, any state in the U.S. can produce bourbon.

There are a number of notable bourbons produced throughout the country including Washington State's Dry Fly Bourbon 101, Iowa's Cedar Ridge Bourbon, and Finger Lakes Distilling's McKenzie Bourbon Whiskey from New York state.

Bourbon must be distilled at no higher than 160 proof (80% ABV).

By keeping the distillation proof low, more congeners are allowed to stay in the final product, which results in more complex flavors.

Bourbon must be stored at no more than 125 proof (62.5% ABV) in new oak barrels.

Note that this means that water is added along with the white dog whiskey from the still to meet this requirement. This further opens up the bourbon and allows the barrel flavors to enhance the final product.

New charred oak barrels are key to the production of bourbon and no whiskey with the label of bourbon can be aged in any other barrel. Early Times is a perfect example of a whiskey that had to change labels because of this regulation. Since they cannot be reused for bourbon, once the barrels are emptied they are often used by producers of other styles of whiskey and liquor.

Bourbon must be bottled at no less than 80 proof (40% ABV), with nothing added except pure water.

Bringing a bourbon to the proper proof for maximum enjoyment is one of the master distillers' tasks. Some bourbons are enjoyable at cask strength, while others need to be brought down in proof to maximize their potential.

Refining the Definition of Bourbon 

While these regulations are very fine-tuned in defining what bourbon is and what cannot be labeled as bourbon, there are still a few questions to be answered:

  • How Long Does Bourbon Need To Be Aged?

While the regulations require bourbon to be aged in new American oak barrels, nothing is said about how long bourbon must be aged in barrel. 

An unscrupulous distiller could age bourbon for 1 day in a cask and legally call it bourbon. Luckily, any bourbon aged less than two years must state how long it was aged on the label.

  • What is Straight Bourbon?

If you see the term straight bourbon, it indicates that the bourbon in the bottle was aged at least 2 years in new American oak barrels.

  • What About Bottled-In-Bond Bourbon?

Bottled-in-bond offerings are the product of 1 distillery during 1 distilling season. These whiskeys have to be aged a minimum of 4 years and bottled at a minimum of 100 proof (50% ABV).

  • How Do Flavored Bourbons Fall In?

Bourbon, by the definition above, cannot have any additives except water. In the process of making flavored whiskeys, a number of ingredients and flavoring agents are added, which then takes them out of the legal definition of bourbon.

While these flavored whiskeys may have a bourbon base, they are often labeled as a whiskey liqueur (liqueur coming from the sweeteners that are often added in the process)Jim Beam Apple is a perfect example.