Beer gets its earthy flavor from hops. Wine gets its sultry sweetness (or delectable dryness) from grapes. So where does whiskey get its unique taste?
If you're a whiskey fiend (like we are), the answer probably won't surprise you: a big part of whiskey's distinctive and rich flavor comes from the type of barrel that it's aged in.
Because of that, not just any old barrel will do. Coopers (barrel makers) need to pay special attention. Here's why.
The spirit usually takes its strongest flavoring from the wood, so it's important to use a wood that won't turn foul. For this reason, most coopers turn to oak. Unlike other trees of similar chemical make-up, oak trees don't have resin channels which can either weaken the strength of the barrel or imbibe it with bad flavors. Also, oak has a natural seal that prevents leakage.
White oak is incredibly popular in the United States. Indeed, the Jack Daniels distillery only uses American white oak. It gives their spirits a creamy flavor, reminiscent of coconut or vanilla.
European white oak, on the other hand, gives a more prune, or dried fruit taste. It's commonly used to storing wines, but some whiskey brands will use it to provide a unique flavoring to their batch.
Flavoring the Wood
Once you have your oak tree, you can't just turn it into a whiskey barrel over night. The wood needs to be seasoned-- not like you season meat, of course. In this case, seasoning means, 'drying.'
First, the wood has to be dried. This can be done either through air drying or in an oven (like a kiln). While many winemarkers prefer air drying (a process that can take years), most whiskey barrels-- and especially bourbon barrels-- are done in a matter of weeks via kiln.
For whiskey, the wood can also be seasoned by charring it. Once the barrel is finished, the cooper will light the inside on fire, giving it a crispy, black layer. This provides a smokey taste to the whiskey, which is pretty popular in the United States. But it also allows the wood to release more flavors, and it works as a filter for the whiskey. Much like in a fish tank, carbon from the burned wood filters out sulfur and other imperfections from the liquid over time, leaving a richer, more impressive taste.
Perhaps not surprisingly, there is a huge market for used whiskey barrels. Not only do people like the decorative uses for them (my mother used them as planters when I was growing up) but other distilleries or breweries will sometimes buy old barrels off of companies to get the unique, flavorful taste of their wood into their own brews.
For example, scotches are only stored in barrels that have been used before. Usually, they are barrels formerly used to store sherry or other wines. Likewise, many beer companies will buy whiskey barrels to store certain batches of their beers in.
What's your favorite barrel taste?