This post is written by Lou Bustamante.
As we shift to darker and cooler days and nights, and the preferences in drinks go from clear to aged spirits, I started thinking about the effects of oak. We have a sense that time spent in barrel imparts the crucial flavoring components that help define the taste of whiskies, rums, and tequilas, as well as smooth out roughness in the final product.
Thinking about this while enjoying a glass of bourbon, I was reminded of a seminar I attended at this year’s Tales of the Cocktail called A Barrel Love Affair that author and American whiskey authority Fred Minnick moderated.
The panel included Brad Boswell (president of Independent Stave Company), Simon Brooking (ambassador for Ardmore and Laphroaig Single Malt Scotch whiskies), Jose "Pepe" Hermosillo (founding partner of Casa Noble Tequila), and Chip Tate (Balcones Distilling). More importantly, the presentation had a whole slew of fascinating facts about oak tress and barrels:
- After the flowers get pollinated, it takes about 120 days for an acorn to reach maturity
- American oak tress don’t start producing acorns until they are about 20 years old
- September and October are the prime months for acorn maturity
- The average age of an oak tree when it gets harvested is about 75 years for American oak trees, 125 years for French oak
- To make barrel staves, 4 to 6 feet of good quality oak (straight pieces free of wormholes and knots) are needed
- The housing market crash, and subsequent decline in construction, improved barrel quality because supplies of oak wood were plentiful
- The composition of oak wood is made up primarily of 4 components: cellulose (45%), oak tannins (8%), lignin (25%), hemicellulose (22%)
- How fast an oak tree grows defines how fine a grain the wood is: fast growing trees have coarse grain, while slow growing ones have fine grain
- Toasting the oak mostly affects the kinds of compounds available for extraction: the lower the toasting, the more accessible lactones (those components that contribute coconut, peach, or simply “oaky” flavors).
- Charring makes more vanillin available for extraction, which aside from contributing flavor, also breaks down into sugars that make the spirit taste smoother.
Just as fascinating were the comparative tastings of the aged and unaged spirits next to each other. In each case there were changes in how the spirit developed beyond the expected vanilla flavors. Certainly there was some smoothness developed, but there was also some complexity and facets like weight and texture, fullness, and how the time in wood highlighted or mellowed out some flavors. The Laphroaig was the most striking, with the peat smoke in the unaged made you feel like your mouth was on fire, but the oak had mellowed it out and added extra dimensions besides smoke.