What happens to the alcohol content of a spirit during the maturation evaporation process?

During the maturation evaporation process, the alcohol content of a spirit decreases slightly due to a phenomenon commonly referred to as "angel's share." As spirits mature in wooden barrels, a small portion of the liquid evaporates over time. This evaporation process can lead to a decrease in the overall volume of the spirit contained within the barrel, and because it is often the less volatile components that evaporate first, this process can lead to a slight increase in the alcohol concentration over time when viewed in a controlled volume context. However, it's noteworthy that in many cases, especially with longer maturation periods, the overall alcohol content might decrease due to the absorption of the wood and the interaction with the environment surrounding the barrel.

The correct interpretation of the question focuses on the fact that the evaporation leads to a slight decrease in the percentage of alcohol in the total volume of liquid within the cask as the non-volatile components (including flavor compounds and some water) tend to remain while some higher alcohols and volatiles may evaporate. This combined with the overall decrease in liquid volume can impact the alcohol content.

Understanding this aspect of maturation helps grasp how the flavors and complexity in spirits may develop over time through interaction with the barrel and the surrounding environment.