Bourbon Empire by Reid Mitenbuler Page B

to the wheel, the simplicity of their design so obvious yet brilliant. They bow in the middle where wooden staves connect the top and bottom, buttressed against each other. The result is maximum ruggedness. If a barrel were to tumble off a rack or gangway it is less likely to break because all the staves supporting each other absorb the impact. Barrels are pieced together like puzzles and held by a few metal bands that don’t touch the liquid. They require no nails, which could rust if touched by liquid and are often made of iron, which would react with the whiskey and ruin it.
    The bowed design of a barrel weighing hundreds of pounds enables an average-sized person to handle it with relative ease. If stored upright, it is easily tilted onto its edge and rolled to wherever it needs to go. Since only a small part of the barrel touches the ground, it can pivot in any direction, its immense weight maneuvered with a light shove. Barrel sizes varied greatly, but were typically forty-eight gallons for much of the nineteenth century when the biggest buyers were beer brewers and oil companies (whale, then petroleum). When those industries moved to steel barrels after World War II and the whiskey industry became the primary customer of wooden barrels, the standard size was increased to around fifty-three gallons because that was the maximum that would fit on the racks installed in most aging warehouses. When full of liquid, barrels that size weigh about five hundred pounds, roughly the maximum weight safely handled by the average dockworker.
    Even the early Romans knew that water and wine stored in charred barrels stayed fresher longer, and by the fifteenth century the French used barrels like this to mellow brandy and give it flavor and color. In America, drinkers in the early nineteenth century also noticed thatspirits transported in charred oak—which is often used for liquids because the wood’s tight grain prevents leakage—tasted better after long voyages. It was a short step from using a barrel as a mere transport device for whiskey to treating it instead as an ingredient.
    Most bourbon makers today estimate that somewhere between 50 and 80 percent of the spirit’s final flavor comes from the barrel. Alcohol is a solvent that over time breaks down elements found in the wood such as cellulose, hemicellulose, and lignin, which are responsible for the vanilla, mint, and anise notes found in bourbon. White oak in particular is loaded with these compounds, which vary depending on the age of the wood, where it was grown, and a host of other factors. These elements are responsible for the swirling platter of flavors reminiscent of butterscotch, vanilla, cinnamon, coconut, and citrus that are found in whiskey.
    When the barrel is charred, the inside looks like burnt toast, but what you don’t see is the layer of wood just beneath the char, where natural sugars are baked and caramelized. Think of a toasted marshmallow, with a blackened outside skin covering the toasted brown patches of crunchy sugar bits hiding just beneath. During warm weather, pressure inside the barrel rises, pushing the bourbon through the char—which filters impurities—and into the toasted layer. When the weather cools, the bourbon contracts out of the wood, taking with it a bouquet of aromas and flavors. If you look at a cross section of a piece of wood from a whiskey barrel, you can see a mark—sort of like a high-water mark on a riverbank—where the whiskey soaked into the wood grain. The whiskey ebbs and flows like a tide, driven by tiny fluctuations in temperature between night and day, melting into larger cycles occurring between the seasons. In the American Midwest and South, where winters are cold and summers are hot, relatively extreme temperature swings can speed up the aging process by causing the whiskey to move in and out of the wood more aggressively. In places where temperature swings are much less dramatic, such as Scotland, whiskey