Authors: Reid Mitenbuler
Barrels have been used to transport all matter of goods—whale oil, fish, nails—since at least the first century
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, when Pliny the Elder noticed their use in the Alps. As a shipping tool, barrels have been compared in importance 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 that
spirits 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 generally requires more time to age.
Since greatness always involves a lot of luck, a barrel size in the
neighborhood of fifty gallons of capacity, although it was designed for transport, also turned out to be ideal for aging whiskey. Distillers sometimes attempt to rush the aging process by using smaller barrels—producing whiskey in a matter of months rather than years—but the results don’t always impress. Small barrels increase the surface-to-volume ratio of wood to liquid, speeding up the extractive process by quickly adding coloring and flavor, but shortchange other parts of the aging process that require more time.
Those other factors include oxidation, evaporation, and esterification, all of which reach their peaks according to different rates that are altered by the barrel size. You can hurry along the extractive process by using a smaller barrel, but that step will finish before the others have had a chance to catch up—this is the difference between simply flavoring a whiskey with wood and “maturing” it. With large barrels, distillers are better able to bring all these different factors in synch. The greater volume allows more time for evaporation to occur, which helps concentrate flavors, while the slower extraction of wood flavors—due to a lesser surface-to-volume ratio—prevents the whiskey from becoming bitter and overpowered after absorbing too many wood tannins.
During oxidation and evaporation, the barrel of whiskey breathes as if it were a lung, driven by alternating cycles of hot and cold temperatures. When the liquid cools and contracts out of the wood, it “inhales” by pulling in outside air through the barrel walls. Oxygen is introduced and slowly absorbed into the liquid, helping develop and mellow its flavor. When the temperature warms, the whiskey expands and the barrel “exhales” air, alongside a small amount of evaporated liquid that is nicknamed “the angels’ share,” an artful term referring to the amount of whiskey lost as vapor.
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The oxidation that occurs while the barrel is breathing is accompanied by a chemical reaction called esterification, where the long, complex molecules found in raw distillate break down and reconfigure. These molecular chains react differently with the wood
each time they come in contact with it, evolving to add even more depth and additional flavors.
Maturing whiskey—balancing all these different factors against each other—requires perfect timing and controlled speed, just like cooking barbecue, another process where perfection calls for patience. When cooking meat, you can speed the process by upping the heat for a shorter time—technically it is cooked—but the proteins and fats don’t break down as perfectly as they do with barbecue cooked slowly with low heat. In the case of bourbon, using a large barrel to age whiskey is the equivalent of barbecuing “low and slow.” The results will usually take at least three years to be worth drinking and the better part of a decade to be worth remembering. Distillers who are unable to afford this kind of time rely on small barrels for aging, the equivalent of cooking meat in a microwave—it’s still edible, if not as enjoyable.
Of course, since taste is ultimately subjective, there is inevitably debate about whether or not small barrels are really inferior. Drinkers with a taste for whiskey aged traditionally with large barrels tend not to like the resinous, spiky qualities of small-barrel-aged whiskey. Distillers who use small barrels typically reply that they’re not going for tradition, that they’re attempting to make something that tastes different and unique. Fair enough, although the subjectivity of taste still doesn’t mean that all whiskey is created equal. In any case, it’s the honest and fiery debates about such matters that make it fun to be a whiskey geek.
Scientists are still working to understand the swarm of factors involved in the aging process. The Buffalo Trace Distillery in Frankfort, Kentucky, has a facility it calls “Warehouse X,” dedicated to aging experiments. Different chambers within the warehouse vary conditions like temperature, natural light, and humidity, all with an eye toward better understanding the maturation process. Chemists at the distillery have found three hundred different wood compounds that contribute to flavor, but have only specifically identified about two hundred of them. All those different compounds affect whiskey differently, and become part of a vast equation of other variables (time, heat, oxidation, esterification, extraction) that distillers must carefully balance. Of course,
there are occasionally exceptions to every rule, which make whiskey production a blend of both art and science. Our understanding is still evolving, but when Americans first started aging spirits in barrels, they understood only one element—wood—and that it made the whiskey taste better, especially when it was burned a little bit.
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Some liquor companies today claim that Kentucky’s whiskey industry was sparked by fallout from the Whiskey Rebellion, when Pennsylvania’s fiercest rebels—those distillers most strongly opposed to the whiskey tax—settled west because it was farther removed from the strong arm of authority. As a modern marketing tool, this reimagining of history helps infuse bourbon with a powerful sense of independence and strong ideals. But the truth is that the roots of Kentucky’s whiskey industry were already established when the rebellion erupted, more in thanks to the savvy efforts of Thomas Jefferson the policymaker, John Filson the mythmaker, Daniel Boone the spokesperson, and people like the prickly dreamer Elijah Craig. Because of them, the population of Kentucky would grow from 73,677 in 1790 to 687,917 by 1830, including many more farmer-distillers as well as middleman merchants. It was this latter group—the salespeople—who turned out to be the unsung heroes of bourbon. They were the ones who established the use of the barrel and likely gave bourbon its name (as always, there is no better embodiment of capitalism than bourbon).
In the early twenty-first century, historians such as Dr. Michael Veach of Louisville’s Filson Historical Society, one of a scarce handful of people to closely study the history of bourbon, began focusing their attention on these salespeople to better understand bourbon’s murky origins. Two brothers were particularly interesting: Louis and John Tarascon, who were born in France and who fled to the United States shortly after the French Revolution started in 1789. By 1807, the brothers were traders between Louisville and New Orleans and had a warehouse in Shippingport, Kentucky, which sits on an island in the Ohio River just west of Louisville. The Tarascons had recruited a group of
French immigrants from New Orleans to Shippingport, where they were perfectly placed to purchase whiskey coming down the river and improve it the best way they knew how: by aging it in charred barrels like many of their fellow Frenchmen had done back home in Cognac, a region known for its legendary brandy. Then they sent it on to other French traders in New Orleans.
Pablo Picasso once claimed, “Good artists borrow, great artists steal.” He stole the quote from the composer Igor Stravinsky, who apparently stole it from the poet T. S. Eliot, who almost certainly stole it from somebody else. Merchants like the Tarascons were familiar with the concept as well, stealing inspiration from abroad that would influence bourbon’s evolution. America certainly didn’t pine for the old continent’s way of life, but it did yearn for its drinks. Counterfeits of foreign spirits abounded, prompting one Philadelphia distiller, Harrison Hall, to write in 1811, “The ingenuity of man was stimulated to obtain a substitute for foreign spirits by the distillation of grain, and, such was the influence of patriotism, or rather, the desire of making money, that a single still put up in a shed, with a worm made of gun barrels, was all the apparatus at this time employed in many places making whiskey.”
Then as now, status and prestige ruled the drinking world, and copying exotic foreign drinks gave distillers access to the deep pockets of those willing to pay for them. Brandies such as cognac already had a storied reputation among the upper class. The drink was a symbol of wealth and luxury, and was considered the apotheosis of the distiller’s art. Aged for long periods in oak barrels—
charred
oak barrels—cognac embodied sophisticated drinking. That was important to those drinking it; what was important to those making it was that they could charge a higher price for the same reason.
Importing cognac from France was expensive, however. For a certain type of frontier entrepreneur, counterfeiting was the answer. Americans excelled at distilling “foreign spirits” able to “deceive very good judges,” Hall wrote. Kentucky grocers were soon selling “Irish Whiskey” alongside “Holland Gin,” “Jamaica Rum,” “Old Scotch,” and “Cognac Brandy,” according to one grocery advertisement from 1817. In a world of lax
trademark laws and without today’s international labeling protections, these spirits were probably those things in name only.
Whiskey made primarily from corn, which is relatively sweet compared to other spirits, gained even more sweetness and flavor from the wood during the long voyages to distant markets. This would have made it all the more appealing to drinkers of brandies like cognac, which is also relatively sweet and mellow. The port of New Orleans quickly noticed that whiskey shipped from Kentucky and other environs of the Ohio River Valley, a lengthy endeavor, gained many of the smoother qualities of sophisticated brandies like cognac.
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A sample of this new kind of western whiskey made its way, via New Orleans, to Philadelphia, where Harrison Hall first tasted it. Some easterners sneered at the frontier spirit, but Hall championed it and criticized his counterparts’ “common prejudice against using corn.” He noted the round warmth contributed by the wood, as well as western distillers’ tendency to barrel the best parts of the distilling run, discarding the lesser-quality heads and feints. Most important, these steps increased the whiskey’s value. There was no profit from selling unaged or minimally aged whiskey—prices for it were the same in local markets of the Ohio River Valley as they were in distant ones, which would have translated into financial losses after accounting for shipping costs. During the first decades of the nineteenth century, whiskey aged somewhere between six and twenty-four months regularly sold for 60 percent more than unaged spirits. A journey downriver by flatboat was a lengthy ordeal, making a trip from Kentucky worth the additional shipping expense only if the whiskey tasted special.