What Is Bourbon?

Seriously. A deep dive into the uniquely American brown spirit and what distinguishes it from other whiskey.

September 8, 2023 6:57 am
Five bottles of elevated bourbon on a table.
Bourbon: American-made (by law).
Danielle Scott/Flickr Creative Commons license

The simple answer to the question “What is bourbon?” is “Bourbon is delicious!” At least when it’s made well by people who know what they’re doing. But we’re guessing you already knew that, so we’re going to dive a little deeper and explain how bourbon is made, what it’s made from, where it’s made and what distinguishes it from other whiskeys (or whiskies). Because — and here’s where your education begins — bourbon is a whiskey. Though not all whiskeys are bourbon! Why not? Read on!

What is bourbon, legally speaking?

Some of these mandates might not make sense to you right now, but not to worry, we’ll explain them as we go along. First of all, the mashbill — the stuff from which bourbon is made — must be at least 51% corn (we’ll get into the other 49% later). It can’t be distilled to more than 160 proof (80% alcohol), because if you higher than that you’ll get a relatively flavorless spirit, essentially a vodka. Vodkas are generally distilled to about 190 proof, by the way. Bourbon can’t go into the barrel at more than 125 proof (62.5% alcohol). But wait, if it’s distilled to 160 proof, why do you have to lower it to 125 proof before it ages? We’ll get into that too! 

Straight bourbon whiskey also has to be aged in new charred oak containers for a minimum of two years — and if it’s aged less than four years, it must have an age statement on the bottle. It has to be bottled at a minimum of 80 proof (40% alcohol) and it can’t contain any flavorings or colorings. And, most importantly, it must be distilled in the United States.

Now that we’ve gotten that out of the way, let’s get a little more into the weeds.

OK, bourbon is distilled from corn. Anything else in there?

Why yes there is! Bourbon is usually distilled from three grains — corn (at least 51%, but there are mashbills that are more than 80% corn), rye and malted barley, which facilitates fermentation, the step in the process that converts the mash (those grains combined with water and yeast) into alcohol. Some bourbons, such as Maker’s Mark or Pappy Van Winkle, contain wheat as the secondary grain instead of rye. These are known as wheated bourbons. There are a few “four-grain” bourbons that employ both wheat and rye, and fewer still which employ other grains like oats or rice. As long as it’s at least 51% corn, though, it’s all bourbon.

Is all bourbon made in Kentucky?

No. This is a common misperception. Kentucky is indeed the bourbon capital of the world and most of the best-known bourbons are made there. But bourbon can legally be distilled anywhere in the United States. Hudson Whiskey’s Bright Lights, Big Bourbon, for example, is distilled in New York, and FEW Spirits’ bourbon hails from Illinois. There’s even bourbon made in Hawaii — we’ve tried it, and…it’s not bad.

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Are bourbon and whiskey the same thing? 

Yes and no. Whiskey is defined, in a nutshell, as a distillate made from fermented grains. So that means bourbon is a whiskey. But bourbon has all these other regulations — chief among them is that it has to be distilled from at least 51% corn and it has to be distilled in the U.S. So all bourbon is whiskey, but there are plenty of whiskeys — from rye whiskey made in Kentucky to single malts made in Scotland and Japan — that are most decidedly not bourbon.

Is Fireball a bourbon?

No, for many reasons, but the most important reason is that it’s flavored. A bourbon must get all its flavoring naturally, from the fermentation/distillation process and (mostly) from the oak in which it’s aged. There are a whole host of other reasons why Fireball isn’t a bourbon (it’s made in Canada, for one thing), but that’s the most important one. There’s no such thing as a “flavored bourbon.”

What’s the deal with corn whiskey? Isn’t that a bourbon?

There are two types of corn whiskey, and different reasons why neither of them is a bourbon. There’s unaged corn whiskey, better known as moonshine, whose mashbill meets bourbon’s requirements. But since it hasn’t been aged in new charred oak for at least two years, it doesn’t qualify as bourbon. Then there’s aged corn whiskey — the most famous of which is Mellow Corn (which you should run out and try right away if you haven’t already). It can be delicious, and it tastes pretty similar to a bourbon. That’s because it is a bourbon, in every way but one — it’s not aged in new charred oak. It’s typically aged in used charred oak, meaning the barrel has previously been used to age bourbon. Used oak imparts less flavor than new oak, so with corn whiskey you’ll get more corn flavor and less of the vanilla/caramel/oak notes for which bourbon is known. 

You said bourbon gets distilled up to 160 proof and yet it can be bottled as low as 80 proof. How does that happen?

One word: water. Water gets added at every stage of the process, from distillation to bottling. Many distillers prefer to add more water earlier in the process, before the distillate goes in the barrel because the water and the spirit can better integrate, with both picking up flavor and coloring from the wood. Most bourbons have still more water added after aging and before bottling, but it’s not like they’re just dumping a bunch of water into a batch of bourbon — it’s a complicated process that can take weeks, in order for the proof to go down without the flavor being too compromised. Bourbon that has no water added between the barrel and the bottle is called barrel proof or cask strength, and the proof will vary between bottlings.

Now I’m an expert. What bourbons should I try?

Glad you asked. We have a few recommendations: The best everyday bourbons. The best high proof bourbons. The best new bourbons of 2023. Or if you’re in the mood for a cocktail, the best bourbons for an Old Fashioned.


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