Behind the Still: The Mash Bill

The Backbone of Flavor & Aroma

Part 2: The Mash Bill is a spirited discussion among distillers and bourbon lovers alike. As a reminder when you read this series, you really should do so with a glass of great bourbon in your hand. You’ll get a better appreciation for the complex aromas and flavors that you enjoy in your favorite bourbon. From proper grain selection and distillation to skillful barrel storage and aging, a lot goes into making bourbon.  Our goal is for you to grow your understanding of what it takes to make an outstanding bourbon.

Very simply, the “Mash Bill” is the list of grains distillers use to make spirits. Mash is the result of the “mashing” process where grains are steeped in hot water to extract fermentable sugars, that when combined with yeast – create alcohol.  When we talk about influencing the overall flavor of a bourbon, the mash bill to accounts for close to 25-30% of it. Being such a major piece of the puzzle, it’s no wonder distillers spend so much time planning their ideal mash bill. So, what grains do we traditionally see in bourbon mash bills and what flavors does each bring to the mix? In general, most bourbons are made using corn along with some combination of rye, wheat, and barley (generally malted). To be called a bourbon, a mash bill must be comprised of at least 51% corn. This leaves an additional 49% to play with, and within that balance lies the distiller’s talented discretion to create unique tasting bourbons.  Let’s look at each grain individually:

Corn: The grain that truly defines Bourbon. Corn was a native grain in the United States that was popular with early settlers. Many of these settlers would distill portions of their crops to protect it from going bad, as well as making it easier to transport. Corn brings much of the sweetness we taste in bourbon as well as a corn character that fades with time while aging in the barrel. 

Wheat: Another way to balance corn’s sweetness by rounding out the palate of a bourbon. Offsetting the richness of heavy corn-based bourbons, wheat softens and lightens the sweetness while also adding depth and mouthfeel. 

Malted Barley: Often overlooked by bourbon fans because it is such a small part of most mash bills. Though malted barley adds some cereal notes to a bourbon, its primary function is to break down starches into sugars that the yeast consumes when creating alcohol.

Rye: A hardy grain that brings spice and earthiness to bourbon which helps to balance the corn sweetness.

With all these factors to consider, how does a distiller decide which grains to use and in what percentages? To explore this, let’s look at our Black Button Distilling Four Grain Straight Bourbon Whiskey. The mash bill of our bourbon is 60% corn, 20% wheat, 11% Malted Barley, and 9% Rye, which as the name suggests, makes it a four-grain bourbon. This mash bill style is an ever-growing category with more being produced each year. By using both rye and wheat as secondary flavoring grains, our distillers must decide how they want those grains to intermingle with the corn and malted barley. For our bourbon we have gone with a wheated bourbon that has a low rye content (9% being considered low rye), but interestingly has 11% malted barley putting it at the higher end of what most distilleries use. This means our bourbon has a unique sweetness that is softer but gives just enough spice to round out the palate. Black Button’s Four Grain Bourbon is perfectly balanced for an approachable, yet full drinking experience – all thanks to a well-crafted mash bill.