As with any dairy-based product, string cheese should be refrigerated until it is ready to be eaten. String cheese is safe to eat for up to 2 hours before it should be refrigerated again.
String cheese is typically made from mozzarella cheese, and makes a good midday snack. It is a good source of both protein and calcium, and each string of cheese contains about 80 calories. In addition to mozzarella, there are versions of string cheese that are a combination of mozzarella and cheddar cheeses. Many types of string cheeses are flavored, such as with cracked black pepper or tomato basil.