Mashbills, Demystified: What 51% Actually Buys You
The legal definitions for bourbon, rye, wheat whiskey, and corn whiskey all hinge on a single percentage. Understanding what that 51% does (and doesn't) constrain changes how you taste.
by My Liquor Library Editorial
American whiskey law leans heavily on a single number: 51 percent. To call something bourbon, the mashbill — the recipe of grains in the fermentation — has to be at least 51 percent corn. To call it rye whiskey, at least 51 percent rye. Wheat whiskey, 51 percent wheat. Corn whiskey is the outlier at 80 percent corn.
What this means in practice is that two bourbons can have wildly different flavor profiles while both being honest about what they are. A bourbon at the 51 percent corn floor with a high-rye supporting bill (35 percent rye, 14 percent malt, say) tastes nothing like a wheated bourbon at 70 percent corn with the rye replaced by wheat. Both are bourbons. Both are doing very different things.
Producers don't have to publish their mashbill, and most flagship expressions don't. But the major-distillery mashbills are well-known in the industry — there are usually two or three core recipes that account for most of the bourbon a given producer ships, with limited expressions sometimes drawn from one-off mashbills. If you're curious which bourbons share a recipe with which, the catalog's mashbill data is one place to look.
The 51 percent floor is a constraint, not a recipe. The 49 percent above it is where a lot of the personality lives. The next time you taste two bourbons side by side and they feel meaningfully different, the mashbill is usually doing more than half of the work.