A Tale of Mash and Oak, Part III: Whiskey Barreling

With some producers, the art of aging has taken on the air of a crazy science experiment.

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Now, the part I personally find especially interesting begins – barreling! I have become intrigued by the barrel-aging process, and it’s worth noting that whiskey is aged in barrels, not bottles. Just because a whiskey has been aged longer does not necessarily mean you’ll enjoy it more.

The typical whiskey barrel is made of oak. While inside this cask, the liquid undergoes a complex series of reactions and interactions with compounds in the wood, all of which will shape its eventual flavor profile and aroma. Barrels also impart color. So if an old, charred barrel is used, the resulting whiskey will most likely have a darker color. The process also largely determines how a whiskey can be classified.

Bourbon, for example, has one of the most particular classifications. It must be produced in the United States (contrary to popular belief, it does not have to be made in Kentucky – any American state qualifies), from a grain bill containing at least 51-percent corn and aged in new, charred-oak barrels. Reused barrels are disallowed, and this mandate is a key reason why bourbon barrels are often used to age Scotch.

Bourbon does not have a specific aging limit or duration, except in the case of straight bourbon, which must be aged for at least two years (there are other specific rules and requirements for bourbon, please see more in the upcoming Part IV: Decoding Whiskey Labels). Compare this to Scotch, which by law must be distilled in Scotland and aged in oak for a minimum of three years.

As I mentioned, distilleries have begun to play around with barrel choices. There are Scotches that have been aged in casks previously used to hold rum, cognac or wine. I recently tried and enjoyed several bourbons which, after aging for a while in new, charred-oak barrels, were transferred into wine casks for additional aging. So don’t be afraid to try something that might sound out of the ordinary.

There is a final step in production, bottling, which typically moderates the whiskey’s final proof or strength. Some distilleries use this stage to mix various barrels or “lots” of whiskey, or to blend in a whiskey from another distillery. When this is the case, it is usually reflected on the label to square up with various regulations (labels have their own nuances, stay tuned for a post dedicated to deciphering them in Part IV: Decoding Whiskey Labels).

This practice is controversial among some enthusiasts. Scotch, for example, can be single-malt or blended. Single-malts come from one distiller and can include multiple casks from the same lot (and yes, there is a single-cask classification). Blended varieties usually contain a number of single-malts from different distillers. 

Next up – Part IV: Decoding Whiskey Labels