Different Oaks

From the bountiful to the elusive, oak adds variety to the world of whisky.

- Jake Emen

In Quercus we trust. There are over 600 species of oak trees in the Quercus genus, to which whisky maturation owes all. Without time in oak barrels, whisky would remain white and fiery, devoid of the toasty, caramel, nutty, or vanilla notes that make our mouths water. It’s simple—without oak, there is no whisky as we know it today. Considering oak’s profound effect on the taste of whisky, it’s not surprising that the details count.

The specific type of oak, the origin of the tree, and all the finer points of its treatment during production will influence the flavors the barrel imparts, whether vanilla or citrus zest, baking spices or dark red fruits, or a myriad of other possibilities. To understand whisky, you must understand oak.

Ancient Technology 

Using oak for barrels isn’t exactly an emerging trend. “Oak became a barrel of choice as far back as the Roman empire,” says Chris Morris, master distiller at Brown-Forman, producer of Woodford Reserve and Jack Daniel’s whiskeys.

Oak is the ideal choice for several signature traits—strength and durability, its liquid-tightness, and suitability to coopering. “The presence of a large volume of medullary rays in the wood structure contribute to this extra strength,” explains Kevin O’Gorman, Midleton’s master of maturation. “The cells of white oak contain tyloses, which are outgrowths on parenchyma cells of the tree’s xylem. These cells dam up the vascular tissue, and it is these clogged pores that prevent an oak cask from leaking.” In other words, not just any tree species can become a proper whiskey barrel.