BARREL AGING Exploring the Origins and Modern Innovations of Barrel Ageing Science Written by NICOLE SHRINER, PH.D.
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arrels have been used to store all types of fermented beverages for thousands of years. Originally, their cylindrical shape was developed to allow one person to move a large volume of liquid. When the Spanish put their sherry in barrels and transported them on ships, they noticed a positive flavor change. This traditional barreled product is called “oloroso” and is one of the first products to be traditionally aged in barrels with the intent to alter the flavor and aroma of the product. A barrel of beer or wine was an approved unit of sea trade in the 1800s. Thankfully, our ancestors figured out that oak was an excellent type of wood to use for holding liquids. Oak is strong but malleable and resistant to bacterial contamination. Most importantly, the structure of oak itself allows it to hold liquids. The wood pores are plugged with tyloses as sap over time turns into heartwood. The
rings in the wood that you would see if you cut a tree in half are made up of xylem rays, which are dense structures that help prevent wine loss. Oak trees harvested for barrels must reach a certain maturity and set of standards to be selected for cooperage. Once the tree has been cut, the tree is cut into sections and quartered. The sections must not have branching, or the staves will not be uniform or sound. The oak staves are then seasoned (dried) to remove excess moisture and to stabilize the wood. This process can take a few years before the staves are deemed ready for barrel construction. The cooper then carefully shapes the barrel by hand using individually selected and shaped staves in a circular fashion. Typically, a metal hoop is placed around one end, forming a flower-like shape. The heads are cut individually for each barrel to ensure a tight and seal-proof fit.
Compounds present in the unaged product are reactive with themselves as well as oxygen. There are numerous reactions that can occur inside a barrel, and this is why some refer to it as a “black box.” 38
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