Despite all the advances—temperature-controlled fermentation tanks, biotechnology, fractional distillation (whatever that is)—the world’s winemakers, distillers and brewmasters still rely on an ancient invention that’s seen almost no modification in 2,000 years: the wooden barrel. But it’s a tool that remains a mystery. What a barrel does to its contents seems more akin to magic than science: The wood drinks in the fluid and the fluid leeches out organic compounds from the barrel; air breathes through the pores of the wood and they all interact in complex ways that scientists still don’t fully understand.
The barrel first showed up a couple millennia ago but it wasn’t until the Romans discovered, around 250 AD, that they were perfectly suited to rolling up and down gangplanks and sturdy enough to survive long sea voyages that their benefits were fully realized. Barrels, in fact, revolutionized the shipping industry: salted meats and fish preserved in barrels made long-distance travel and exploration commonplace.
It took a while before the barrel’s effects on wine became apparent. When the Roman Empire extended to an outpost in England, around 300 AD, they found that wine shipped from the continent tasted better in England than it did back in France. Says Peter Fisher, operations manager for the Napa Valley-based cooperage Barrel Builders, “Something had happened to the wine in the barrel and made it better.”
Without the barrel, important beverage styles might never have developed. Madeira, among the most popular wines in the 1700s, literally cooked in barrels in the holds of ships sailing the tropical seas, imparting a unique taste to the wine and extraordinary longevity—vintages a century old can taste better than the day they were made. Madeira producers purposely sent wine on long sea voyages to “madeirize.”
Spirits like brandy, whiskey, rum and tequila become mellow from barrel aging. Cognacs are rated by French law according to the barrel aging they receive, the finest slumbering in casks for decades. (VS has a minimum of two and a half years in oak; XO Cognacs must spend at least six and a half years in barrels.)
Barrels also figure prominently in Belgian brewing, notes Rob Tod, president of Allagash Brewing Co. Lambic ales were, and still are, aged in wooden barrels. Not only does the wood impart flavor to the beer, but bacteria and wild yeast hiding in the barrels’ seams give the ales their unusual character.
Over the last century, stainless steel and plastic barrels have replaced wooden ones for most purposes, and more recently pallets and containers have made shipping in barrels obsolete. But maturing wine and spirits in wood has gained even greater importance, because consumers have come to appreciate the taste of oak and equate quality with barrel aging.
For centuries oak has been the first choice among barrel makers, as its tight grain holds liquids well. Suitable trees are about 120 years old. Only two to four 60-gallon barrels can be made from a single oak as “only about 30 percent of the tree is usable,” Fisher explains. New oak barrels cost $300 to $1,000. They’re “the second most expensive thing wineries buy, after the grapes,” says Fisher, noting that if a wine sells for $25 a bottle, the barrel’s cost is amortized into the price. “If you’re selling the bottle for $4, you’re not using barrels.”
Barrel Builders sells new French oak barrels for nearly $900 each. American oak barrels cost roughly half that. Standard wine barrels hold about 60 gallons; wineries may need hundreds or even thousands of them—and the useful life of a barrel is only about four or five years. Barrels coopered for whiskey are 40 or 53 gallons and are generally cheaper because of the size and use of less-expensive American oak. But, under strict federal regulations, Bourbon can be aged only in new oak barrels, and so Bourbon makers often sell used casks to other distillers.
Of the hundreds of oak species, only three are commonly used for wine and spirits barrels: Quercus Alba, or American White Oak, which grows in the eastern United States; and two European varieties, Quercus Petraea and Quercus Robur, grown in France and Hungary. American Oak adds lots of vanilla and coconut flavor; Quercus Petraea contributes more tannins, which give wines structure for aging, and fruity notes are often found in Quercus Robur barrels.
Seasoning the planks and toasting the finished barrels create oak lactones, or aromatic compounds. Toasting—scorching the barrel’s interior with an open flame—causes complex chemical reactions. It degrades wood lignins and cellulose, bringing out a number of volatile compounds, most importantly vanillin. For wine barrels, care is taken to not burn the wood but turn it tawny colored; whiskey barrels are burned for a heavy char.
Toasting is the most important part of barrel fabrication, says cooper Russell Karasch at the Barrel Mill in Avon, Minnesota. His cooperage makes barrels with light, medium and heavy toast. Winemakers pick the amount of toasting according to the type of wine they’re making and the desired effects. Barrel aging adds cream, butter and smoke to Chardonnay and smooths rough tannins in Cabernet. Whiskies, brandies, rum, tequila and other spirits get some barrel aging to add a golden color and vanilla, coconut and caramel flavors.
The oak barrel has actually shaped the way we think beverages are supposed to taste. Bourbon wouldn’t be Bourbon without the caramel from American oak. And some people will shun a California Chardonnay if it doesn’t reek of oaky butter and vanilla, while others avoid it for that very reason. In fact, some say too many wines today taste more of wood than fruit. “There’s a tendency towards using more and more oak,” says Fisher, who opines that many American wines are over-oaked. He places some of the blame on wine critics. “They say, ‘That’s what we like and we’ll give you a 94 score.’”
The situation is exacerbated by the increased use of American barrels, which have a more pronounced impact on flavor. And some producers, especially the inexpensive labels, have done away with barrels and use “barrel alternatives.” Barrel staves, oak chips, even sawdust are added to wine in stainless steel vats to extract flavor—and greatly speed up the process. The latest wrinkle comes from infusion spirals, corkscrew-shaped wooden rods that offer a lot of surface area and are toasted for flavor.
“It’s all a matter of personal taste,” says Karasch, who sells the infusion spirals. “If you don’t like oak, even a little is too much.” He points out that 70 percent of wine doesn’t get any barrel aging at all. “If they don’t like oak, they can drink that.”
Single-malt Scotch became popular in the 1980s. These unblended whiskies are traditionally aged in oak barrels to add color and complexity. Historically, Scots used Sherry casks to mature Scotch whisky, but when the Spanish Civil War disrupted the supply, they turned to Bourbon barrels from the United States. At the turn of the millennium, a new variation emerged, so-called “wood-finished whiskies.” Single-malt whiskies are further matured, or “finished,” in barrels that had previously held other wines and spirits.
For single-malt enthusiasts, variously wood-finished Scotch is all the rage. Aficionados can take their pick from malt whiskies aged in Sherry or Port casks, Burgundy barrels or barriques that once held grand cru Bordeaux. “Glenmorangie was one of the first distilleries to treat its whiskies this way,” says Kevin Erskine of thescotchblog.com. Now the Glenmorangie portfolio includes Scotch finished in Port, Madeira, Burgundy and Sauternes barrels. Its latest introduction is matured in barrels from the First Growth Bordeaux Chateau Margaux, a limited-edition that retails for as much as $450 a bottle.
The super Scots—the big distillers—are on trend, too. The Balvenie offers PortWood and DoubleWood versions of its malt; the Glenlivet features its 12-year-old in both a French and American Oak finish; the Macallan offers its Fine Oak line. And the latest finishing schools, says Erskine, are barrels that once held rum or sweet wines, as well as brand-new barrels.
Most beer was never aged in wood. That is, until the craft-beer revolution in America, a reaction against the mass-produced pallid pilsners that dominated the market for over half a century. The movement has gained momentum (the craft beer segment grew 12 percent in 2006 while domestic beer was flat).
An offshoot of the craft segment are the so-called “extreme beers,” ales with big flavors and alcohol content approaching wine’s. These brews improve with age, and microbreweries are experimenting with barrels. Up in Maine, Allagash boasts an entire line of barrel-aged beers. “We’re making big beers that can be laid down; like wine they’ll improve with barrel and bottle aging,” says brewmaster Tod. Allagash’s Curieux matures in old Jim Beam Bourbon casks. “It gives the ale coconut character, vanillin character, herbal notes and a little bit of Bourbon, of course.”
Tod plans to experiment more with different types—French oak, Port casks. “Barrels,” says the brewmaster, “offer a huge palette of flavors.”