As you might guess, the term “barrel aging” is exactly as it sounds: the process of aging spirits in a wooden barrel. But what you may not know is that the process of barrel-aging alcohol has been around for thousands of years. And the science behind barrel aging is a complex and tricky thing to master. Whether you’re curious to try barrel aging at home or simply want to dive into this thousand-year-old tradition, here’s what you need to know about the ancient art.
The smooth experience of whiskey can be credited to the intuitive and scientific process of barrel aging, a technique rooted in Celtic history and still utilized today. Suggested by its name, barrel aging involves patient and attentive maturing of a spirit within a wood barrel—a symbiotic relationship between barrel and spirit that influences the aroma and flavor of whiskey and other spirits like bourbon and rum. Originally used as a durable container for shipping spirits, the happy accident of wood barrels gives distillers an effective and creative means for producing spirits rich in quality and enjoyed by novices and connoisseurs alike.
What happens during barrel aging?
Raw ingredients (water is a key ingredient, along with barley or other grain and yeast) are placed within a wood barrel and aged for a varied length of time, determined by factors such as the temperature and humidity of the surrounding environment. Over time, the wood allows for vapor to pass outside of the barrel as well as integrate oxygen into the aging process. This in-and-out flow occurs in a fluid and ongoing manner.
In addition to the important role wood plays in the exchange of air, the barrel also acts as a filter. Wood barrels used for aging spirits are charred or toasted prior to filling with the necessary ingredients, which leaves a charcoal coating that acts as a filter, removing flavors that are disagreeable to the palate. As the charcoal pulls flavors that can produce a distasteful spirit, the wood blends in its essence, mingling vanillin, tannins and the smoky appeal associated with spirits such as whiskey.
Types of barrels used during the aging process
The type of barrel refers the specific wood species and the choice to use a new or previously used barrel. American white oak is a common barrel used for aging spirits, but other options include French oak, maple, cedar and hickory. Each type of wood lends its own unique flavors that are considered when deciding the intended flavor of the finished spirit. American oak is typically touted as a favorite due to its qualities of vanilla and smoky flavors, along with low tannins that are associated with a bitter or sharp taste.
Selection of the barrel extends beyond the type of wood to include a new or previously used barrel. Spirits like bourbon or wine may require a new barrel, free from flavors of another spirit, while a distiller may choose a previously used barrel for spirits like whiskey. During the aging process, the wood absorbs flavors of the aged spirit, which can be infused in any future aging that occurs in the same barrel. Aging whiskey in a used barrel offers creativity as a distiller seeks to find the ideal blend of flavors for different types of whiskey.
Why is barrel aging so important?
Wood barrels seem to instinctually command the aging of spirits. The barrels direct airflow—gradually inviting oxygen into the aging process while allowing evaporation to take place, and filter out flavors that would otherwise produce an unwelcome taste. Moreover, the wood works to decrease the level of ethanol in a spirit, therefore eliminating the sensation of rubbing alcohol.
Barrel aging creates a finished whiskey or spirit product full of aroma and flavor and without qualities that can diminish the essence enjoyed by many. To appreciate the outcome, one must acknowledge the importance of the process. And to pay gratitude to every sip, taste or bottle of whiskey, one must tip a tumbler to the intelligence of barrel aging.
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