Ah, whiskey. Few spirits are so complex in their taste and so diverse in their varieties. Although scotch has long been famed for its diversity, its American cousin bourbon has as much history and unique character. You just have to approach it with the knowledge of what you’re tasting.

Once you understand bourbon, you’ll realize that not all bourbons are the same, and you’re going to have to do some experimenting to find the right bourbon for you.

First of All: What Is Bourbon?

There are many myths about what makes a bourbon, but the definition is simple. To be a bourbon, a spirit must be:

  • Distilled from a grain bill of 51% corn
  • Made in the US
  • Aged in new, charred white oak barrels
  • Distilled at less than 160 proof (80% alcohol by volume (ABV)) and barreled below 125 proof
  • Bottled at a minimum of 80 proof
  • Contain no artificial coloring or flavoring

This definition is designed to protect the essential character of bourbon, but, as you’ll see, it can lead to some confusing distinctions.

Why Is It Called Bourbon?

The origins of the spirit, and its name, are not well documented. The most common explanation for the name is that because so much of the whiskey was made in Bourbon County in the Kentucky Territory, much larger than the modern Bourbon County.

But bourbon historian Michael Veach has a different theory. He believes it was actually named for Bourbon Street in New Orleans, which was even then the place to be for high times. So people marketing the spirit wanted it to be associated with this vibrant party scene. It was only later that the story about Bourbon County was constructed.

Why Is Tennessee Sour Mash Not Bourbon?

Jack-Daniels-Black-No-7-Tennessee-Sour-Mash-Whiskey_750 ml

Now that we’ve defined what bourbon is, let’s explore some of the things it’s not. One of them is Tennessee sour mash. So what’s the difference?

Almost everything about Tennessee sour mash whiskey meets the criteria for bourbon: 51% corn? Check. Made in the US? Check. Aged in new oak barrels? Check. And the strengths match up, too.

The difference is what is called the Lincoln County Process. In the Process, the spirit is filtered through maple charcoal before aging. That gives the whiskey a bit of a head start on acquiring the complex woody flavors it can acquire in the barrel. We’re not sure this really counts as an “artificial” flavoring, but it’s considered one for the purposes of the law.

Feeling slighted, Tennessee hit back with a 2013 state law that requires all Tennessee whiskey must use the Lincoln County Process. An exception was written in for Benjamin Prichard’s Tennessee Whiskey,

So what’s up with the sour mash? Sour mash is actually a process that’s common to bourbon and Tennessee whiskey. Sour mash is when you use spent mash from a previous batch as a starter for your new batch, similar to the way you use an old bread starter for sourdough.

Wheaters & High Ryes


Once you’ve got the 51% corn requirement satisfied, the rest of your grain bill can be anything else you want, but the two big contenders in bourbon are wheat and rye.

If a bourbon contains more wheat than rye, it’s called a wheater. If it’s more rye than wheat, it’s called a high rye bourbon. But, remember, to be a bourbon, it still has to have 51% corn. If it tips too far to those other grains, it becomes a wheat whiskey like Burnheim or a rye whiskey.

Single Barrel, Small Batch, and Cask Strength Bourbons

So, what’s the difference between a single barrel and small batch bourbon? Both of these bourbons are hand-picked by the master distiller.


As the name implies, a single-barrel bourbon comes out of a single barrel. The distiller picks one barrel that he believes has a particular character that’s worth preserving. Although all bourbon technically is going through the same distillation process, put into very similar barrels and aged in basically the same place, there are still subtle variations in materials and conditions that can create distinct flavors. Selecting a single barrel bourbon gives you a chance to sample a unique flavor that will probably never exist again.

With small-batch bourbons, the master distiller selects a few barrels to be blended and bottled together. There’s no maximum number defined for a “small batch,” but it’s usually about a dozen. These are also unique flavors, but because they’re created by design and combining larger quantities, it’s more likely that this flavor will be repeatable—and reliable.


But whether the bourbon comes out of a single barrel or several, bourbon is often diluted as it’s bottled to reach proof. But if the bourbon is bottled as it comes out of the barrel, it’s called cask strength. The bourbon went into the barrel at 125 proof, and it could still be that, now, although that’s unlikely. But it will definitely be at least 80 proof. Cask strength is sometimes called barrel proof.

Bottled in Bond


Back when America was great, you could put anything you wanted in a bottle and sell it as bourbon. People tried to pass vodka, gin, rum, and anything else they wanted as bourbon, adding color with tobacco, iodine, or anything brown they could find. This didn’t just make terrible bourbon, it was making people sick.

But in 1897, the US passed the Bottled-in-Bond Act, the first consumer protection law in US history. It stated that a Bonded Spirit had to be aged at least four years, bottled at exactly 100 proof, and be distilled in one location. Few spirits these days meet all the requirements of the Bottle Act, but those that do produce a very reliable quality.

Why Don’t All Bourbons Declare Their Age?

By law, bourbons are only required to declare their age if they’ve been aged for less than four years. In blends, the youngest bourbon used is considered the age of the whole. Since bourbons must be aged for a minimum of two years, it’s not common for bourbons to have to declare their age.

There isn’t as much of a craze about aged bourbons as there has been about aged scotch. But there are some aged bourbons out there.

What Happens to the Barrels When the Bourbon Goes in the Bottle?

Bourbon must be aged in a new barrel. But during the aging process, the barrel acquires a lot of flavor. This makes the barrel perfect for aging other tipples.

Many bourbon barrels are used to age some delicious beers, but most famously they’re used to make scotch, helping to give it its unique complexity.

But that’s a subject for another day.