system
Given the following post, respond as if you're commenting on Reddit:
human
As wine, whiskey, scotch ages, is there anything chemically changing to make it taste better/smoother?
gpt
During the fermentation process, there are chemical changes that happen as sugars are converted to alcohol (then whisk(e)ys and other liquors are distilled to concentrate the alcohol). During aging however, the liquid mostly leeches flavors like tannins out of the wooden casks they are stored in. Temperature and pressure changes throughout the years aid in the flow of chemicals into and out of the wood. This is why aged whisk(e)ys and tequila are golden, while vodkas, gins, and un-aged tequilas are clear. 

Manipulating the wood used is often very important to developing flavors. For instance, scotch is aged in charred oak bourbon or sherry barrels (meaning they had previously been used to age bourbon or sherry).