Sour Mash vs. Bourbon: Is There Actually a Difference?

Sour mash is a term thrown around in the whiskey world more often than a football gets thrown by Tom Brady.

And with so many different whiskeys to choose from, it’s important to know the difference between sour mash vs. bourbon.

Some whiskeys are labeled sour mash, some bourbons are labeled sour mash, and some sour mash whiskeys aren’t labeled as such.

Talk about a freakin’ mess…

In this article, you’ll learn the difference between bourbon and sour mash (and if there really even is one at all).

Sour Mash vs. Bourbon: What’s The Difference?

Comparing sour mash whiskey and bourbon is kind of like comparing apples to Granny Smith brand apples.

Bourbon is a broader category of American whiskey that must be made with at least 51% corn (among a few other requirements). 

“Sour mash” refers to a specific process used by some distillers to add a distinct flavor to their whiskey.

A sour mash whiskey can actually be classified as bourbon since both types of whiskey are made under the same restrictions (51% corn in the mash, aged in new charred oak barrels, etc). 

And some bourbons even call themselves sour mash whiskey (like Michter’s Original Sour Mash).

So, is there a difference between sour mash and bourbon?

Yes in that they are literally two different things, but the drinks themselves are very similar.

Let’s dive further into this.

What Is Sour Mash Whiskey?

When you see “Sour Mash” on the label, it means the whiskey was distilled using the sour mashing process. 

What does that mean?

Simply that distillers used part of the fermented “mash” (a mixture of grain, yeast, and water)  from the previous batch to create the new batch. 

Think of it as a sourdough starter for baking bread…but for whiskey instead.

Using part of the original batch in new batches does a few key things:

1. It keeps pH levels stable so no unwanted bacteria form in the mash. 
2. It helps distillers maintain consistent flavors in their future batches

So, “sour mash” isn’t really a type of whiskey per se. It refers to the process used during the distillation process. 

And pretty much all major bourbon and Tennessee whiskey distilleries use the sour mash process even if they aren’t labeled a “sour mash whiskey”.

What Is Bourbon?

Bourbon is a type of American whiskey that’s made from at least 51% corn and aged in new charred oak barrels.

In order for whiskey to be considered a bourbon, it must also be:

• Made in the U.S. (but not specifically in Kentucky)
• Distilled to no more than 160 proof
• Barreled at no more than 125 proof
• Bottled at no less than 80 proof

There are literally laws about this. 

In 1964, the U.S. Congress recognized bourbon whiskey as a “distinctive product of the United States” and outlined the rules of the spirit (listed above) in Title 27 of the Code of Federal Regulations.

Crazy, right?

Surprisingly, there aren’t any age requirements for a whiskey to be called bourbon.

The only requirements are for being labeled a “straight bourbon” (2  years minimum) or “bottled-in-bond” (4 years minimum).

So, Is There a Difference Between Sour Mash and Bourbon? Kinda But Not Really.

The difference when it comes to bourbon vs. sour mash is really semantics.

Sour mashing is a process most distillers use.  And they use it when making bourbon a lot of the time.

So, it’s kind of just a label distilleries like to throw on a bottle sometimes.

That’s really all there is to it, my friend.