What is the name of the material added to change the colour of an oak matured spirit?

The addition of caramel is a common practice in the production of certain oak-matured spirits, particularly in whiskey and brandy. This substance is used to enhance the color of the spirit, giving it a richer, more appealing hue that reflects the aging process in oak barrels. The use of caramel is widespread in the industry as it provides a consistent color across batches without altering the fundamental flavor profile of the spirit. It's important to note that not all spirits require caramel for coloring, and some are bottled without any additives, showcasing their natural color derived from aging.

Other options like oak chips are primarily used to impart flavors rather than change color, while natural extracts and food dyes also do not have the same primary role or widespread application as caramel.