How Much Does Mashbill Affect the Flavor of Whiskey?

Jun 05, 2023

How do the grains that go into a mashbill impact the flavor of your go-to whiskey? (Ikon Images via AP Images)

The word "mashbill" is thrown around a lot in the whiskey world, but what exactly is a mashbill? Even more importantly, how much of a role does a mashbill factor into the final flavor of your favorite dram?

Before we go any further, it's important to understand what a mashbill, aka grain bill, is. First, we must understand what mash is. Whiskey is made from grains. Before the distillation process begins, the grains are crushed and mixed with hot water. Once whiskey mash ferments, it is similar to beer and for that reason is often referred to as "distiller's beer."

A mashbill is essentially a grain recipe for a whiskey — it tells you how much of each grain went into the mash a whiskey was distilled from. Every whiskey has a mashbill, although some producers keep theirs secret.

There are four types of grains most commonly used in a mashbill: corn, rye, wheat and malted barley.

Mashbill plays a significant role in the flavor profile of whiskeys. Different grains offer different flavors once mashed and distilled. However, mashbills aren't the only determining component in the flavor of whiskey.

"A lot of people put a lot of emphasis that mashbills are the end-all-be-all of flavor, and I think it would be irresponsible to say they don't contribute, but my hypothesis is in 99% of the scenarios, there's something else also happening that's just as impactful, probably chemical or process or maturation based," Whiskey Raiders Spirits Critic Jay West said.

Factors that affect whiskey's flavor beyond the mashbill include how long the whiskey was aged, the type of wood the barrels containing the whiskey during maturation are crafted from, the environment the whiskey was in while aging and the type of yeast used.

As an example, consider Four Roses’ 10 bourbon recipes. By definition, bourbon must be made from at least 51% corn. Four Roses uses two core mashbills, Mashbill B, which is lower in corn content and higher in rye, and Mashbill E, which is higher in corn content and lower in rye. But from only two mashbills come 10 recipes, thanks to Four Roses’ use of various strains of yeast. (Image: Four Roses)

Corn often presents as a sweeter grain, displaying flavors of buttercream frosting or sweet confectioner's sugar. Whiskeys with heavy percentages of corn in the mashbill can channel major Frosted Flakes flavors, in West's opinion. Of all of the grains used in a mashbill, corn demands the most time barrel aging to develop all the pucker power of tannin.

It is difficult to find mashbills composed singularly of corn, as those whiskeys can run into the pitfall of lacking complexity. There is a trend developing within small craft distillers to challenge this, and producers like High Wire Distilling Co. and Reservoir Bourbon are experimenting with 100%-corn whiskeys, however, according Punch Magazine.

Since bourbon is always distilled from a mashbill of at least 51% corn, it tends to be a sweeter spirit.

Rye holds lots of spicy, herbaceous aromas, yet the grain's diverse array of flavors are largely dependent on the individual species of rye. Polish, Ukrainian and Canadian ryes proffer up a veritable range of aromas that range from dill pickle to mint.

Some distillers use higher percentages of rye in their mashbill if they want a particularly spicy whiskey, yet 100% rye is extremely difficult to distill. This is because rye doesn't have enough accessible sugar to kick off fermentation without the assistance of additional enzymes. One way around this issue is by using a percentage of malted rye in the mashbill, as enzymes are produced as grains malt.

"The more rye you have in the mashbill, the dirtier the ferment is, so when you run it through the still it's gummy and greasy, and you have to stop the still after a couple of runs to clean out the sediment," West said.

Rye is also distinctive in that once distilled, it often takes less time than corn, barley wheat to begin shedding its youthful notes, typically due to rye spice and developing tannin. For this reason, young ryes often perform better than young bourbons, single malts or wheat whiskeys.

Rye whiskey must be distilled from a mashbill of at least 51% rye. Beyond rye whiskey, rye is often found as a secondary grain to corn in bourbon.

Grains of wheat can be used in a mashbill. (AP Photo/Matt Slocum)

If butterscotch, toffee and honey sound like heaven to you, you may want to consider whiskeys with heavier percentages of wheat. Wheat has a lot of range and can go "purely in the dessert spectrum," West said. Wheat smooth and less spicy than other grains like rye. Wheat whiskeys must have a minimum of 51% wheat in the mashbill.

Wheat shares two common factors with corn: One is that 100% wheat whiskeys are difficult to find, and the second is that it needs a bit more extended aging time in order to take on greater complexity. Younger wheat whiskeys may taste a bit different than what one might expect and yield flavors similar to young rum. These flavors go away with elongated exposure to oak barrels.

"All these grains when they’re really young or right off the still have a green sapling note, or like a pulpy cardboard note," West corroborates, "… people who drink whiskey really expect to have some maturation built in so the flavor profile they expect does have tannin."

Although less common than rye, wheat is frequently found as a complementary grain in bourbon. Wheated bourbons are those that have mashbills with wheat as the second-most-common grain, behind corn.

Barley often presents plenty of bready and cereal aromas in addition to big cocoa and chocolate notes. Barley is malted nearly 99% of the time during the distillation process, so the sugars inside of the grain are able to be easily accessed and consumed by yeast during fermentation. There are some rare occasions where you may see barley unmalted to add a bit of flavor variation, but these instances are few and far between.

There are some occasions when distillers will add malted barley or malted rye to high rye mashbills and promote some accessible sugar for the fermentation to kick off, and when this is the case expect to get plenty of chocolatey cocoa notes.

Barley is extremely common as a tertiary or quaternary grain in American whiskeys, often used to add enzymes in order to speed up the fermentation process.

There are loads of alternative grains emerging on the market as whiskey producers look to diversify and stand out amidst the competition.

As the category continues to expand and grow in popularity, there are a few common alternative grains that keep popping up: rice, oats and sorghum.

West describes oat-based whiskeys as having lots of viscosity, meaning a thicker texture that yields a dram that feels well-aged, with lots of oatmeal cookie flavors.

Rice whiskey is a growing category and SevenFiftyDaily purports that these types of grain yield whiskey with plenty of fresh, floral qualities. Rice whiskeys take quite well to barrel aging, making them attractive to smaller distilleries.

Sorghum is a naturally gluten-free grain that grows in the American South. The grain is fairly easy to grow and is often crushed like sugar cane prior to being turned into syrup, making it closer to rum than whiskey. Sorghum spirits are a bit of a hot topic for distillers, as no one knows exactly what category they fall into, according to Distiller Magazine. They tend to be relatively easy to drink and have mellow spice aromas.

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Cynthia Mersten is a writer/editor for Whiskey Raiders and has worked in the Beverage Industry for eight years. She started her career in wine and spirits distribution and sold brands like Four Roses, High West and Compass Box to a variety of bars and restaurants in the city she calls home: Los Angeles. Cynthia is a lover of all things related to wine, spirits and story and holds a BA from UCLA's School of Theatre, Film and Television. Besides writing, her favorite pastimes are photography and watching movies with her husband.