I've heard a rumor that in other parts of the country, the weather is turning colder, leaves are starting to drop from the trees, mountain men and other rustic types are gathering wood for their fireplaces, and drinkers are turning their bloodshot eyes toward the brown spirits.
Me? I have the air conditioning on as I type this. It's about 80°F out there. Then again, my bloodshot eyes never turn away from brown spirits even when the temperatures crack the triple digits, but I'm unusual that way.
A few months ago, I provided a primer on Scotch terms. Today, I thought I'd turn my gaze inward and explain a few things about good old bourbon whiskey.
Start at the top, or if you will, the bottom: what's bourbon?
By law, bourbon must be made from a grain mixture that's at least 51% corn (in a bit, I'll explain what the other 49% is). Bourbon is aged in new charred-oak barrels, and it's distilled to no more than 80% alcohol by volume (ABV). When it's pumped into the barrels, it enters the casks at no more than 62.5% ABV. Finally, when it's bottled, it has to be at least 40% ABV.
The mash bill of a bourbon is its recipe. Bourbon must, as noted earlier, contain at least 51% corn, but the other grains in the mash bill depend on the tastes of the distiller. Any grain is possible; some distillers use rice, oats, and other grains. Most bourbons, though, are a mix of corn, wheat, and rye, and sometimes barley.
A bourbon in which the second major ingredient is rye is known as a high-rye bourbon. Rye is a spicier, richer grain than either corn or wheat, and high-rye bourbons are usually spicier and richer as a result. Examples include Bulleit and Wild Turkey.
A bourbon in which the second major ingredient is wheat is known as a wheater, or a wheated bourbon. Wheated bourbons are sweeter than high-rye versions. Examples include Maker's Mark and W. L. Weller. Do not confuse this with a wheat whiskey such as Burnheim. That one is 51% wheat, which means by law it's not bourbon.
An age statement is simply a disclaimer about the age of the youngest bourbon in the bottle. So, for example, a bourbon with an age statement of 10 years is made up entirely of bourbons that are 10 years old and up. A bourbon older than four years does not need to carry an age statement, by law. So if you see one that does, it's usually for older bourbons—generally, ten years of age or older.
One term you might see on a label is "Straight Bourbon." This category has additional legal requirements beyond those of regular bourbon. Straight bourbon must be at least two years old. If it's older than two but younger than four years, it must carry an age statement, and that age statement must reflect the youngest bourbon in the bottle. Finally, straight bourbon may not contain added colorings or flavorings.
Another term you'll see is "Sour Mash." A sour mash is made by taking a portion of previously used mash and adding it to a fresh batch. This makes the mash taste a little sour, but it doesn't affect the flavor of the finished whiskey. The process is roughly analogous to using a sourdough starter when making bread, though unlike a sourdough starter, a sour mash is made of dead yeasts.
The process has two advantages: first, it help ensures consistency from batch to batch, and second, it lowers the pH of the batch, leading to more efficient fermentation.
The term "sour mash" implies that there might be such a thing as a "sweet mash," and this is true, although rare. In a sweet mash, only fresh yeast is added to the batch. Sweet mash has a higher pH, meaning the mash ferments differently, producing flavors you won't generally find in sour mashes. Woodford Reserve has experimented with sweet mashes in recent years.
Before most bourbons (indeed, most whiskeys in general) are bottled, they're diluted with water to bottling proof. Usually, this is 80 proof, or 40% alcohol by volume, which is the lowest a bourbon can be diluted to and still be called a bourbon. Adding water is a way to stretch the supply of bourbon, making it less expensive to produce. The lower proof is also seen as being more palatable to consumers. Some bourbons, though, have less water added, and are sold at higher proofs, such as 90 proof, 95, 100, 101 (Wild Turkey, of course), or even higher.
Also known as barrel-proof bourbon, a cask-strength bourbon is undiluted. If it comes out of the barrel at 124.6 proof, that's what you get in the bottle. Cask strengths vary from barrel to barrel, based on a number of factors, such as warehouse placement, weather conditions, and so forth. The strength of the bourbon depends on how much of the liquid has evaporated over time. If more alcohol evaporates out, it'll be lower proof. If more water evaporates, it'll be higher. Therefore every barrel is different. Booker's, for example, ranges from about 121 proof to 130.
More Bourbon on Serious Eats
Five Essential Bourbon Cocktails
Serious Eats Goes Behind the Scenes at Maker's Mark
Stocking Your Home Bar: Bourbon Advice from the Experts
Amazing New Bourbon: Four Roses 2013 Limited Edition Releases
What's Your Favorite Bourbon Cocktail?