Mozzarella is a type of cheese that is traditionally made from water buffalo milk, and it's the main ingredient for Italian dishes like pizza and lasagna. It has a soft, springy texture when it is fresh, but as it ages, sharp crystals form on its surface.
Due to this characteristic of mozzarella, it needs to be kept in water so that its structure doesn't become too stiff or brittle; the cold water keeps the proteins in the cheese more elastic and gives them greater structural integrity. The additional moisture also helps ensure that none of the flavor-enhancing enzymes present in mozzarella get lost during storage. Additionally, because most chillers can dry out food products stored inside them over time—which can compromise both their flavor and texture—mozzarella's water bath helps keep all these elements intact while keeping bacteria at bay until you’re ready to use it.