Production

The quirks of quercus

Mark Gillespie looks at American Oak
By Mark Gillespie
Here’s a trivia question for you: how many types of White Oak are found around the world?For now, let’s talk about one of them: Quercus Alba, also known as American White Oak. It’s the wood most often used for maturing whisky around the world, largely because it’s the wood used for maturing Bourbon and Tennessee whiskies. By U.S. law, those barrels can only be used once for Bourbon and Tennessee whiskies, which means there’s a massive supply of used Quercus Alba barrels for distillers around the world to work with.

However, the law doesn’t specify the species of oak distillers must use. How, then, did distillers settle on Quercus Alba, given that there are plenty of White Oak and Red Oak (Quercus Rubra) trees growing in the traditional whiskey-producing regions of North America.

“If you made a barrel out of red oak, by the end of the day all your whiskey’s on the floor,” says Chris Morris of Woodford Reserve. Quercus Rubra is too porous to hold liquid, but it makes great furniture. Most other hardwoods are too brittle to be made into barrels.

“We have experimented with what I call exotic woods (non-oak), Morris says. “We have had our cooperage make barrels out of sugar maple, hickory, pecan, ash, and sassafras as finishing barrels.“ His lab tests the potential for exotic woods by adding toasted and charred chips of cherry, pecan, and other woods to beakers filled with Bourbon. “Those that taste good, we’ll see if we can make barrels out of them,” he says. Those experiments led to the 2010 Woodford Reserve Masters Collection release of Bourbon finished in sugar maple barrels.

Other distillers have experimented with wood at different steps of the process, primarily during the distilling process. Chip Tate of Balcones Distilling in Waco, Texas earned the Whisky Magazine Icons of Whisky award for U.S. craft distillers in 2012 for his Balcones Brimstone whiskey, which used spirit infused with the aroma of burning scrub oak before maturation to deliver a smoky campfire-like taste.

“They have this aroma, this character, this beautiful presence and essence”


“Three or four out of 10 taste it, love it from the first sip,” Tate says. “There’s always the one that will say it’s not my thing…but the others taste it and are kind of taken aback on that first sip. They take another sip and what scared them off nearly the first sip unfolds into all of these other flavours, and most people end up hooked.”

Rock Town Distillery in Little Rock Arkansas, has used a Scotch-like concept for its Arkansas Hickory Smoked Bourbon. Distiller Phil Brandon steeps his red winter wheat for several days, then dries it before distillation in smokers filled with hickory. The technique is legal under U.S standards for Bourbon, which ban any kind of added flavouring agents.

Rick Wassmund of Virginia’s Copper Fox Distillery dreamed of making whiskey matured in barrels from apple and other fruit trees, but settled on using fruitwoods before and after distillation for his single malt and rye whiskies. Like Brandon, Wassmund smokes his grain before distilling with smoke from burning apple and cherry logs, but the maturation process is where Wassmund’s vision comes to life. He uses toasted applewood chips inside the barrels to enhance the flavour of the whiskies.

“We’ve got a source at an old orchard that’s never been sprayed,” Wassmund says. “We get the mature trunks of these old trees, and when you split them, they have this aroma, this character, this beautiful presence and essence that we try and capture and put into the barrel.”

The Copper Fox single malt and rye whiskies don’t carry age statements, but are bottled as Wassmund deems them ready in small batches. In addition to the matured spirits, Copper Fox also sells its new make spirits for both types of whiskies in what it calls the “Distiller’s Art” series, complete with small barrels for home maturation. Just as with the barrels used at the distillery, the miniature barrels are made of new Quercus Alba charred oak.

The answer to the opening question is: 36. This includes Quercus Alba’s European cousin, Quercus Robur, the wood traditionally used by sherry and other wine producers and sought after for Scotch Whisky production.


Wine and oak



Olivier Humbrecht is one of the stars of the French wine world, with winemaking in his family dating back as far as the early 17th century. Domaine Zind-Humbrecht in Turckheim, Alsace regularly garners international awards for its produce, but Olivier Humbrecht is also a passionate and knowledgeable whisky aficionado, with strong views on oak and whisky, as well as on oak and wine.

“For our wines we use oak casks (called ‘foudres’) which range in size from 9,000 to 10,000 litres. They are old and we keep them as long as possible,” explains Humbrecht. “At present, 90 per cent of our foudres are over 60 Years Old.

“The oak comes from the Vosges mountains or mid-Europe, and we use oak for its capacity to clarify the wine better (because we do not filter or rack it), and we have fewer reduction problems, as oak will allow some gas exchange and is less sealed than any other tank type. We also work bio-dynamically and so we believe in the exchange of certain energies between the wine and its environment. We do not like new oak, and therefore American oak is a no, because we do not want to impact our wines with oak aromatics, especially fruity, white wines.

Only very rich reds (like Spanish wines) would be able to cope with a high percentage of American new oak.”

When it comes to single malt Scotch whisky, Humbrecht says: “I like sherry casks, even first fill, and Bourbon barrels as well. I tend not to like wine barrels too much because I feel they bring flavours that overpower the delicacy of some whiskies. Most wine barrels are heavily sulphured once empty in order to prevent the development of fungus inside. I am sure that many distilleries do not rinse them before filling, so they keep more of the wine aromatics, but in doing so they also introduce a lot of sulphur into the whisky.

“The way whisky is made today, most new makes are quite neutral (unless peated, of course). Casks are often used to add extra flavours and body to products which would be quite bland without them. If I want oak flavour, I would chew a piece of oak, if I want Sauternes flavours, I’ll buy a bottle of Sauternes!”