Although processed cheese was first invented in 1911 by Walter Gerber of Thun, Switzerland, it was James L. Kraft who first applied for an American patent for his method in 1916. Kraft Foods also created the first commercially available sliced processed cheese, which was introduced in 1950. This form of sliced cheese with its derivatives were to become ubiquitous in the United States, most notably used for cheeseburgers and grilled cheese sandwiches.
Processed cheese has three technical advantages over unprocessed cheese: extended shelf-life, resistance to separation when cooked, and the ability to reuse scraps, trimmings and runoff from other cheesemaking processes.
Traditional cheesemaking inevitably produces 'scrap' pieces that would not be acceptable for supermarket display; production of processed cheese from cheese scrap allows the cheesemaker to add value to otherwise unmarketable scrap. Processing can turn these scraps into new presentable shapes for repackaging and sale.
The use of emulsifiers in processed cheese results in cheese that melts smoothly when cooked. With prolonged heating, unprocessed cheese will separate into a molten protein gel and liquid fat; processed cheese will not separate in this manner. The emulsifiers, typically sodium phosphate, potassium phosphate, tartrate, or citrate, reduce the tendency for tiny fat globules in the cheese to coalesce and pool on the surface of the molten cheese.
Because processed cheese does not separate when melted, it is used as an ingredient in a variety of dishes. It is a fairly popular condiment on hamburgers, as it does not run off, nor does it change in texture or taste as it is heated.
Inclusion of artificial additives in processed cheeses and the higher levels of salt are other subjects of criticism.
In the United States processed cheese is defined, categorized, and regulated by the Food & Drug Administration under the U.S. Code of Federal Regulations Title 21 (Food and Drugs), Section 133 (Cheeses and Cheese Related Products). Pasteurized process cheese can be made from a single cheese or a blend of several cheeses. Cream, milkfat, water, salt, artificial color, and spices may also be added. The mixture is heated with an emulsifier, poured into a mold, and allowed to cool. The definitions include:
The various definitions are mainly used to distinguish minimum/maximum amounts of cheese ingredient, moisture content, and milkfat.
The best known processed cheese in the United States is marketed as American cheese by Kraft Foods, Borden, and other companies. It is orange, yellow, or white in color and mild in flavor, with a medium-firm consistency, and melts easily. It is typically made from a blend of cheeses, most often Colby and Cheddar.
Despite the common usage, American Cheese also has another definition. It can also refer to a mild, pale white to yellow cheddar.
The term store cheese is sometimes informally used to describe American Cheese and similar American cheddars.