A whisky mash bill is the recipe of grains used to make the spirit. It specifies the types and proportions of cereals in the mash, which directly influence the flavour, texture, and character of the finished whisky. While single malt Scotch has a simple mash bill of 100 percent malted barley, other styles such as grain whisky, bourbon, rye, and many world whiskies use a combination of different grains.
The Definition of a Mash Bill
The mash bill is expressed as percentages that add up to 100 percent of the grain content. For example, a bourbon mash bill might be 70 percent corn, 15 percent rye, and 15 percent malted barley. In Scotch single malt, the mash bill is always 100 percent malted barley, but in Scotch grain whisky it can include wheat, corn, or other grains alongside some malted barley.
The grains are milled and mixed with hot water to extract sugars before fermentation and distillation. The specific mix of grains determines much of the whisky’s base flavour.
A Brief History
The concept of a mash bill comes from the need to define and control the grain recipe for consistent spirit character. In the United States, legal definitions for categories like bourbon and rye specify minimum percentages of certain grains in the mash bill. In Scotland, the mash bill for single malt is legally fixed at 100 percent malted barley, but grain whisky mash bills have more flexibility.
In Scotch history, distilleries traditionally sourced local grains, leading to mash bills that reflected regional agriculture. Modern supply chains allow for more uniform sourcing, but the principle remains the same: the mash bill is the foundation of the whisky.
Types of Mash Bills
Single Grain Mash Bills – Used in Scotch grain whisky, often based on wheat or corn with a smaller proportion of malted barley for enzymes.
Bourbon Mash Bills – At least 51 percent corn by law, with the remainder made up of rye, wheat, and malted barley.
Rye Mash Bills – At least 51 percent rye by law in the US, producing spicy, herbal flavours.
Wheated Mash Bills – Replace rye with wheat for a softer, sweeter profile.
Impact on Flavour
Corn – Sweet, full-bodied, with caramel and vanilla notes.
Rye – Spicy, dry, and aromatic, with pepper and clove flavours.
Wheat – Soft, gentle, with bread and pastry notes.
Malted Barley – Nutty, biscuity, and adds enzymes to convert starch to sugar during mashing.
Mash Bill in Scotch Whisky
For Scotch single malt, the mash bill is fixed and simple: 100 percent malted barley. The variety of barley, level of malting, and whether peat is used during drying will influence flavour, but there is no variation in the grain mix itself. In Scotch grain whisky, mash bills can vary more widely and may be designed for lighter, more neutral spirit to be used in blends.
Frequently Asked Questions
Does the mash bill determine all of a whisky’s flavour?
No. It sets the foundation, but fermentation, distillation, and maturation have major impacts too.
Can two whiskies with the same mash bill taste different?
Yes. Production methods, still design, and cask type can produce very different results from the same mash bill.
Why do Scotch producers not change mash bills for single malt?
Because the legal definition of single malt requires 100 percent malted barley.
Conclusion
A whisky mash bill is the blueprint for the spirit, determining the grains that form the backbone of its flavour. Whether it is the simplicity of malted barley in Scotch single malt or the complex mix of corn, rye, wheat, and barley in bourbon, the mash bill is the starting point for everything that follows in whisky-making.