Processed cheese products such as Kraft Singles often contain some cheese, milk, milk solids, water emulsifiers, salt, rennet, food coloring and vitamins. Each type of processed cheese has a different mixture of these ingredients, but the key components are cheese and several additives, mainly emulsifiers.
Processed cheese products became an American staple in the 1940's, when James L. Kraft began mass manufacturing it and bringing it into the American supermarket culture. It was received with widespread positive reaction and has remained a popular choice for consumption ever since. The well-known, easy-to-melt nature of processed cheese products is due in part to the fact that these items often have a number of emulsifiers, which makes the melting process much easier than with standard cheeses.
The number of additives and preservatives in processed cheese products increase the shelf life and stability when the product is stored or shipped. Because of the viscous flexibility of processed cheese products, they can be sold in a variety of forms, from the familiar Kraft Singles slices to the canned cheese products that are used as toppings for crackers or deli meats.
The most popular uses for the single-slice version of American processed cheese products are the grilled cheese sandwich and the cheeseburger.