What’s The Difference Between Bourbon and Sour Mash? (2023)

Last Updated on August 22, 2023 by Lydia Martin

Ah, bourbon-the nectar of the Gods and the water of life, a smooth, complex spirit that Americans have enjoyed for centuries. 

But what exactly is bourbon, and why is it confused with sour mash? Is there a difference between bourbon and sour mash? Here’s the answer! 

Sour Mash & Bourbon Compared

Michter's Sour Mash Whiskey

Sour mash basically refers to a particular process used by distillers to add a specific flavor to the whiskey. Bourbon is a category of American whiskey made following distinct requirements and restrictions.

A sour mash whiskey can be classified as bourbon if it is made under the same bourbon restrictions (51% corn, aged in new charred oak barrels, etc).

A whiskey maker makes sour mash whiskey by adding a portion of still-fermenting mash to the new batch of spirits. On the other hand, bourbon uses all new ingredients for each batch. It gives the bourbon a sweeter flavor profile. As a result, bourbon typically has richer color and deeper flavor than sour mash whiskey. 

Here’s A Closer Look

Here's A Closer Look


James C. Crow is credited with developing the sour mashing process in the early 1800s. He discovered that he could easily control the fermentation process by using a portion of mash from the last batch of spirit. The sour mash refers to the process where the previously fermented mash is used for new batches, just like the starter in sourdough bread. 

Bourbon has a long and rich history in the United States, dating back to the early days of American settlement. Made in Kentucky, it gets its name from bourbon county. Moreso, it is made from a mash of corn, rye, and barley and matured in new oak barrels.

Production & Distillation

Bourbon Mash Bill Process

The sour mash whiskey adds some of the spent grain from the previous batch of spirit into the fermented mash like sourdough bread. The process is like a sourdough starter that adds beneficial bacteria and enzymes which help to break down the starches and sugars in the grain. The sour mash is then distilled and aged in new charred oak barrels. 

Bourbon whiskey comes from grain mash, typically corn, rye, and barley. It is aged in new charred oak barrels for at least two years (straight bourbon), but it can be aged for much longer. In fact, there is no aging requirement for a whiskey to be called bourbon [1].

Jack Daniel’s uses a bourbon recipe, but it has a different distillation process because it uses the Lincoln County Process and whiskey sour mash. 

Alcohol Content

Bourbon whiskey must be distilled to no more than 160 proof (80% alcohol by volume) and bottled at no less than 80 proof (40% alcohol by volume content). It typically has an alcohol content of between 40% and 50% at bottling time. 

Most sour mash whiskeys have an alcohol content of around 40%. It means that they are slightly less alcoholic than other types of whiskey. 


Woodinville Bourbon

Major bourbon and Tennessee whiskeys use the sour mash technique in their production. A portion of the fermented grain mixture from the last batch of whiskey starts the fermentation process for the new batches. 

Also, it is used to produce other types of whiskey, including Tennessee whiskey, and they specify it on their labels. Tennessee whiskey distilleries like Jack Daniel’s put a label on their Tennessee whiskey bottles. 

The label is one of the most important aspects of any straight bourbon bottle. It tells the story of the distillery, the distiller, and the bourbon itself. Moreso, the label must include the distillery’s name and address and the distiller’s signature.

Mash Bills

The most common bourbon mash contains: 70% corn, 15% rye, and 15% barley; or, 65% corn, 35% rye; or, 51% corn, 37% rye, and 12% barley. While not all whiskey uses the same mash bill, the final product must be made with at least 51% corn to be called bourbon.

On the other hand, the term sour mash is used to describe a mash used in the distillation process, which is a combination of water, yeast, and grain.

The said combination is removed from an older batch of alcohol to start the fermentation of a new batch. Check out the most popular sour mash whiskeys here.


Is bourbon made from sour mash?

No, bourbon is not made from sour mash. However, some types of bourbons use the sour mash process. The sour mash process helps control the pH level of the fermenting alcohol before adding live yeast.

Is Maker’s Mark a sour mash whiskey?

Yes, Maker’s Mark is a sour mash whiskey. The sour mash bourbon uses some residual yeast and mashed grains from the last batch. It allows for a more consistent flavor profile from batch to batch.

Key Takeaways 

All bourbon and sour mash is whiskey, but not all sour mash is bourbon. There is a difference between bourbon and sour mash, but it’s not really logical to compare them. 

Sour mashing is a process used in different types of whiskey like rye whiskey, bourbon, and Tennessee whiskey. To make sour mash whiskey, a portion of the “mash,” or grain mixture, from a previous batch of whiskey is used as the starter for the new batch. It adds bacteria to the new mash, which helps to create a unique flavor profile.

Meanwhile, to be called bourbon, whiskey needs to follow strict requirements. 



Lydia Martin

Lydia Martin hails from Redmond, Washington, where you’ll find some of the best cocktail bars and distilleries that offer a great mix of local drinks. She used to work as a bar manager in Paris and is a self-taught mixologist whose passion for crafting unique cocktails led her to create Liquor Laboratory. Lydia can whip up a mean Margarita in seconds! Contact at [email protected] or learn more about us here.

3 thoughts on “What’s The Difference Between Bourbon and Sour Mash? (2023)

  • May 25, 2022 5:51 pm at 5:51 pm

    Lydia, I’ve followed most of your articles and post on the web. I want to thank you for your insight, information, knowledge and help when it comes to my favorite beverage, Whiskey

  • June 3, 2022 12:02 pm at 12:02 pm

    Most bourbons are made using a sour mash.


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