Why we use barrels to age whiskey
When making a whiskey, maturation is the final and most important step!
Whiskeys are aged in wooden barrels which is where they get all of their color and most of their flavor. There are many different types of barrels but the most common for whiskey production is American White Oak or French Oak.
Oak is the perfect wood for cooperage due to its pour size and allows for oxygen to be exchanged. When the whiskey is placed into the barrels, they form a tight seal to ensure the optimum aging and prevent spilling.
Whiskey barrels are typically charred on the inside. Burning the inside of the barrel brings the natural wood sugars to the surface to be incorporated into the whiskey. It also creates more opportunities for whiskey to soak into the wood. Barrels can be charred to different levels ranging from one to four. The higher the number, the more burnt the barrel is. The more charred the barrel, the more smokey and woody the whiskey will become.
There is a constant exchange of oxygen going through the barrel, which is very important for flavor development of the whiskey. Oxygenation creates something fondly referred to as “The Angel’s Share,” a fancy way to say some of the liquid evaporated. The amount of evaporation is dependent on the climate of the region. This is one of the reasons why a Bourbon from Colorado will taste much different than a Bourbon from Kentucky and one reason why Scotch whiskey is aged for a longer period of time. The rate of evaporation in Colorado is quite high due to the dry climate, which some say results in a cleaner whiskey. As evaporation takes place the proof of the spirit will increase due to the lowered water content. Evaporation is also getting rid of some of the congeners that might create an off flavor or aroma in your finished product.
Fun fact: Scotland has a very consistent wet, cool climate which causes Scotch whiskey to be aged much longer due to the snail-like pace of evaporation.
Different types of barrels are used for different types of whiskey. For example Bourbon legally has to be aged in Charred New American Oak Barrels. Scotch whiskey on the other hand is typically aged in used barrels, they can be old bourbon barrels or wine barrels. This also plays into why Scotch whiskey is aged for much longer time periods. The more times a barrel has been used the less woody character will be left over.
Barrel aging is the reason why no two whiskeys are the same, even if they’re made in the same facility. One end of the rack house can have completely different conditions than another making every barrel unique.
