Chemical Mechanisms of Whiskey Maturation

Abstract

Studies of the chemical mechanisms involved in the maturation of whiskey showed that the formation of acetaldehyde, acetic acid, and ethyl acetate originates in the distillate, while ethanol lignin, aromatic aldehydes, sugars and some acetic acid are reaction products of the distillate and wood components.

Storage conditions affect these reactions. For example, barrel wood is more reactive when a barrel is charred, causing a higher congener level in the product of the first filling than that of a comparable filling in an uncharred barrel. As the barrel is reused, the product congener level approaches that of the uncharred barrel. The effect of recharring the barrels on congener formation is also discussed.

The entry proof also affects the levels of congeners present in the final product. As the entry proof increases, those congeners that originate from barrel components decrease. Warehouse temperatures are directly related to the rate these congeners are formed. The implication of these relationships on the maturation of whiskey is discussed.