Bourbon & Rye

To be called bourbon, the mash must be at least fifty one percent corn and the spirit must go into new charred oak containers, with nothing but water added before bottling. It has to be distilled at no more than one hundred and sixty proof, barrelled at no more than one hundred and twenty five, and bottled at eighty proof or above. There is no minimum age unless the label says straight, which requires at least two years in wood. Rye follows the same American framework, rye in place of corn. Canadian rye is defined separately and need not meet that mark. Nothing in any of it mentions Kentucky.

A new charred barrel gives up far more than a refill cask does. The char layer filters the spirit while the toasted wood underneath releases vanillin and wood sugars, which is where bourbon finds its vanilla, caramel and coconut notes. Kentucky warehouses swing hard between summer and winter, pushing spirit into the wood and drawing it back out. Bourbon can taste mature at an age where a Scotch malt is still adolescent. Because the rule requires a new barrel every time, used bourbon casks are sold on, and a great deal of Scotch and Irish whiskey matures in them.

Corn brings sweetness and body. Rye brings pepper, dill and a dry finish, so a bourbon with a high rye content tastes sharper and less rounded. Some distillers use wheat instead as the secondary grain, which makes a softer bourbon usually described as wheated. Malted barley is almost always in there in a small proportion, because it supplies the enzymes that convert starch into fermentable sugar.

No. Bourbon can legally be made anywhere in the United States, though Kentucky holds the deepest concentration of large producers, and the phrase Kentucky Straight Bourbon carries that origin on the label.

American rules only force the issue below four years, where the age has to be declared. Above that a producer may leave it off, and many do, because the bottling is blended from barrels of several different ages. A bottle without a number is not automatically young. If the label says straight, it has had at least two years in new charred oak behind it.

Swap one for the other in an Old Fashioned or a Manhattan and the drink changes character rather than quality. Bourbon rounds everything out and carries sugar, while rye pushes back and comes out drier.