Everyone knows that a well-aged whiskey has style. The older it is, the more elegant, flavorful, and sophisticated it becomes. It is deeply ingrained in our culture.
However, only a few people truly comprehend the intricacies of the aging process. It turns out, aging whiskey is not just a marketing ploy – it is far from it. The years spent in aging barrels are what truly define whiskey.
In this article, we aim to delve into the science behind aging whiskey. This process is truly beautiful and deserves our utmost admiration. So read on and become an expert in barrel aging.
Why is Barrel Aging So Crucial?
If you want to understand the significance of barrel aging, the easiest way is to take a sip of unaged whiskey. Unaged whiskey, also known as white dog whiskey, has gained popularity in recent times, and honestly, we’re not entirely sure why.
It’s not that white dog whiskey is necessarily terrible; it’s simply lacking all the elements that make whiskey exceptional. It lacks the complexity of flavors and aromas that one associates with a well-aged whiskey.
All the additional flavors and aromas that elevate whiskey above vodka come from the aging process. So, let’s explore the scientific aspects.
Choosing and Preparing the Barrels
A well-aged whiskey begins with carefully selected and prepared oak barrels. Oak is the ideal wood for aging whiskey due to several reasons:
Oak has lower resin content compared to other types of wood. Resins impart a strong sappy taste, which isn’t favored by many whiskey enthusiasts.
Oak contains numerous delightful organic compounds (which we will discuss later) that contribute to whiskey’s flavor.
Oak is porous enough to allow oxygen to enter the barrel and vapors to escape, but not so porous that the whiskey will leak out.
The history of the barrel also plays a role. For example, bourbon-style whiskey is aged in unused barrels, while scotch-style whiskey uses barrels previously used for aging bourbon.
Once the barrel is acquired, it undergoes pre-treatment. Typically, the inside of the barrel is heated until it chars. This charcoal acts as a filter, providing the whiskey with a smooth and crisp taste.
The Influence of Aging Barrels on Whiskey’s Flavor
Aging barrels do more than just filter whiskey; they infuse it with flavor, color, and scent.
This is the essence of the aging process. As temperatures fluctuate in the warehouse, both on a daily and seasonal basis, the pressure inside the barrels rises and falls accordingly. When the pressure is high, the whiskey permeates the barrel’s pores, and when the temperature drops, the whiskey seeps back out.
Over the course of many years, this process allows the whiskey to extract various delectable compounds from the wooden walls of the barrel. The three most significant compounds worth mentioning are lignin, lactones, and tannins.
Lignin breaks down into other compounds that contribute to the whiskey’s clove and smoky flavors. It also imparts vanillin, which unsurprisingly gives whiskey a vanilla flavor.
Lactones are responsible for a buttery, coconut-like taste. Oak barrels from the United States tend to have higher lactone levels compared to their European counterparts, hence why bourbon often exhibits a buttery profile whereas scotch does not.
Lastly, tannins provide the whiskey with an astringent taste referred to as “wood spice.” While most barrels contain plenty of tannins, they are released at a slower rate compared to lignin and lactones. As a result, the longer a whiskey is aged, the more pronounced the wood spice flavor becomes.
European oak generally contains more tannins than American oak, which contributes to scotch’s delightful wood spice taste.
The Impact of Temperature on the Aging Process
As mentioned earlier, temperature fluctuations are essential for the aging process. Without them, the whiskey would fail to extract the necessary compounds from the wood.
However, the magnitude of these temperature fluctuations also matters. In Kentucky, where bourbon is produced, there are significant daily temperature variations between hot days and cold nights. Conversely, in Scotland, the home of scotch, temperatures exhibit greater consistency.
That is why scotch is usually aged for longer periods compared to bourbon. The extreme temperature changes in Kentucky expedite the aging process for bourbon.
ACE Whiskey Distillation Equipment
Aging and Evaporation
Evaporation is a final component of the aging process. Over time, alcohol, water, and certain compounds evaporate from the aging barrels. This phenomenon is known as the “angels’ share.”
While it may seem like a loss, evaporation is crucial to the aging process and signifies a healthy whiskey.
Alcohol and water evaporate under subtly different conditions. In a humid environment, more alcohol evaporates than water, while a dry environment yields more even evaporation.
Regardless of the environment, evaporation results in the gradual loss of the whiskey’s distinct characteristics over time. It is indeed possible to over-age a whiskey.
Give It a Try
Now that you have gained a deeper understanding of the science behind barrel aging, it’s time to try it for yourself. With a little patience, you can transform any ordinary liquor into something truly delightful.