On the Importance of the Seasons

One point that fascinated me at Friday’s lecture was the impact of seasonal changes on whiskey. Traditionally, distillers have left barrels of bourbon to age in unheated warehouses or barns all year ’round. It was of course the only practical thing to do once upon a time, because let’s face it, even if there was a way to heat a warehouse in winter in 1875, who would have wanted to waste the fuel? It wasn’t until the modern age, when distillers started to experiment with temperature, that the impact of seasonal fluctuations on flavor were truly understood.

It all has to do with pores in the barrel wood. In warm weather wood expands and the pores open, allowing the barrel’s contents to flow in. Once there, the alcohol and water set to work dissolving various components in the wood. When the weather cools, the pores contract, squeezing the bourbon back into the barrel. Thus a sort of slow-motion pumping action is created which, over time, infuses the bourbon with flavor. Pretty cool.

I also learned that over the years, more than one distiller has experimented with “chipping” bourbon, i.e. pouring oak wood chips into the barrel in hopes of speeding along the infusing process. The problem? Instead of bourbon surrounded by wood you have wood surrounded by bourbon. Temperatures don’t fluctuate as dramatically inside the barrel, meaning there’s less inflow and outflow in the wood, and you get a different flavor profile — one that’s heavier in harsh wood tannins versus rich and mellow vanilla-type notes.

As Mr. Spock would say: fascinating.