Bourbon and rye: America's barrel whiskeys

A rickhouse in late summer smells of caramel and hot wood, and the barrels inside are doing the quiet work that turns a clear corn spirit into bourbon. Rye shares that building, that barrel and most of that process. The difference lives in the grain bill and in what the grain does to the finished glass.

What they are

Both whiskeys are defined by the United States standards of identity, which read like a recipe written by a lawyer. Bourbon must come from a fermented mash of at least 51 percent corn. Rye whiskey needs at least 51 percent rye. Both must be distilled at no more than 160 proof (80 percent alcohol), entered into new charred oak containers at no more than 125 proof, and bottled at 80 proof or above. Nothing may be added to bourbon beyond water; coloring and flavoring are forbidden for it specifically.

Two further words carry weight on the label. Straight means the whiskey has aged at least two years and contains no neutral spirits or additives; if it is under four years old the label must state its age, a rule that applies to any whiskey not bottled in bond. Bottled in bond is older and stricter: one distilling season, one distiller at one distillery, at least four years in wood, nothing added or removed except by filtration or similar physical treatment, and bottling at exactly 100 proof. The label must identify both the distilling plant and the bottling plant. The rule dates to the 1897 Bottled-in-Bond Act, passed to stop dealers from stretching bonded whiskey with cheaper spirit.

There is no Kentucky clause. The standards of identity list bourbon among the domestic whiskey types and define it by grain, still proof and barrel rather than by state; a state or region may be named on the label only if the whiskey was distilled and aged there. A 1964 concurrent resolution of Congress declared bourbon a distinctive product of the United States. That is the whole of the geography.

How they are made

Grain is ground and cooked. A typical bourbon mash runs closer to 70 percent corn than the 51 percent floor, with the balance in malted barley, which supplies the enzymes, and a flavoring grain. Rye in that slot gives spice and weight; wheat gives a softer, sweeter whiskey. Rye whiskey flips the proportion, and the high-rye mash bills of Pennsylvania and Maryland style bottlings run far higher.

American distillers ferment the whole mash, solids included, and most practice sour mashing: a portion of the spent liquid from the previous distillation, the backset, is added to lower the pH and favor the yeast. Kentucky's limestone-filtered water, low in iron and rich in calcium, is part of the regional story. Distillation is usually two stages: a continuous column still, often called a beer still, brings the spirit to around 50 to 60 percent, and a copper pot called a doubler or thumper lifts it to the low or mid 60s. The clear spirit is called white dog.

Then the barrel. It must be new, it must be charred, and in practice it holds about 53 US gallons of American white oak. Cooperages toast the staves and then set the inside alight; char levels run from one to four, and the deepest char opens the wood to give vanillin, caramelized sugars and the amber color. In a multi-story rickhouse the top floors run hot and dry, so proof tends to rise as water evaporates; the bottom floors run cool and damp and proof can fall. Producers rotate barrels or blend across floors. Whatever leaves the barrel into the air is the angel's share, a poetic name for ordinary evaporation.

Styles and regions

Within bourbon the useful axis is the flavoring grain. High-rye bourbons taste of pepper and baking spice; wheated bourbons taste of soft bread and honey. Age adds tannin and oak sugars, and in a hot climate it adds them quickly, which is why very old bourbon can turn woody. Tennessee whiskey follows the bourbon rules and adds maple charcoal filtration before barreling, a requirement of Tennessee state law since 2013 rather than a federal category.

Rye went nearly extinct in the twentieth century and has come back with the cocktail revival. Modern rye splits into Kentucky-style bottlings with just over 51 percent rye, which read as spicier bourbon, and the higher-rye styles that taste of mint, dill and rye bread. Canada uses the word rye more loosely for its blended whisky, which is another subject.

Kentucky makes roughly 95 percent of the world's bourbon, but distilleries in Indiana, Tennessee, Texas, New York and nearly every other state now produce it legally and well.

In cocktails

The Old Fashioned is the proof of a whiskey: sugar, bitters and dilution with nowhere to hide. A high-rye bourbon or a rye at 90 to 100 proof holds its shape as the ice melts. The Manhattan was built for rye, whose spice cuts the sweet vermouth; a wheated bourbon makes a softer, dessert-leaning version. The Whiskey Sour wants the rounder sweetness of bourbon against lemon and sugar. The Sazerac is a rye drink by tradition and by taste: absinthe rinse, Peychaud's bitters and a dry, peppery spirit. The Boulevardier swaps gin for whiskey in a Negroni, and bourbon's caramel bridges Campari and vermouth in a way that rye leaves sharper.

Buying by style

Decide what the whiskey must do. For stirred drinks, a bottled-in-bond rye or a straight bourbon at 100 proof survives the dilution and costs less than its age statement suggests. For sours and highballs, a standard 80 to 90 proof bourbon is correct and economical. For sipping, taste along the grain axis before chasing age: a well-made six year wheated bourbon can be more pleasant than a tired fifteen year bottling. Treat non-distilling producers honestly: many excellent ryes are sourced from large Indiana distilleries and say so, and the label words straight and bottled in bond tell you more than a brand story.

Folklore and fact

The belief that bourbon is Kentucky's alone is the category's most repeated error. It is Kentucky's by overwhelming share, by history and by marketing, but the federal rule says United States and stops there. The name itself is a softer mystery: Bourbon County, Kentucky was named in 1785 for the French royal house, and barrels shipped from the region carried the words Old Bourbon, which is the most defensible origin. Stories that a single preacher invented the charred barrel belong to brand lore; the earliest references to charring date to the early 1800s and describe a practice already spreading.

Sources

• 27 CFR 5.143, Whisky, and 27 CFR 5.88, Bottled in bond (Cornell LII).
• Congressional Record, May 15, 2014, Senate resolution recognizing bourbon (govinfo).
• Kentucky Distillers' Association, home page.
• Difford's Guide, "Bourbon history" and "Bourbon: how is bourbon made?".
• 27 CFR 5.74, Statements of age and percentage (Cornell LII).
• Tennessee Code 57-2-106, Tennessee whiskey (FindLaw).