Magazine looks at finer points of how barrels play a major role in the taste of bourbon

Making the perfect batch of bourbon often depends on the barrel, and where it's placed and what weather and temperature conditions it endures. It's something bourbon makers have been grappling with for 2,000 years, as they try to produce gold. In a story for The Atlantic, Wayne Curtis looks into the science, in some cases accidental science, of bourbon making. (Atlantic photo)

"It’s well known that a good portion of a whiskey’s flavor comes from the barrel it ages in, but less well known is just how large a portion we’re talking about," Curtis writes. "I recently asked a dozen or so people involved in the bourbon industry how much of the flavor comes from the barrel, and how much comes from other elements, such as the grains used or the distillation method. Most said that 60 or 70 percent of the flavor comes from the barrel, and one went as high as 80 percent. No one I spoke with estimated the proportion at less than 50 percent—meaning one of the trendiest liquors on the contemporary cocktail scene owes most of its flavor to a technology that’s thousands of years old."

"Barrel flavoring takes place in part because alcohol is a solvent that gradually breaks down elements in the wood over time. White oak in particular has an abundance of appealing flavors, including vanilla, nuts, and coconut, as well as butterscotch notes from sugars in the wood, which are caramelized during charring," Curtis writes. "During the summer, heat increases pressure inside a barrel, and some liquor pushes itself through the char in the barrel’s wooden pores, enabling the carbon to filter out impurities. During the winter, the liquor moves in the reverse direction. The process is repeated with less vigor during the heating and cooling cycles of day and night. So merely by sitting in a barrel, whiskey is slowly being filtered through the barrel."

Bourbon makers have experimented for years with new ways to create new tastes and flavors, switching from small barrels to larger barrels, aging it for different lengths of time, trying different ways of moving barrels to interact the liquor with the wood and where and how to store the barrels. Sometimes nature does experiments; Buffalo Trace Distillery in Frankfort, Ky., which turned out one its best batches after opening barrels that survived a tornado but were exposed to the elements. (Read more)