American cheese is one of the many varieties of cheese that are pasteurized. Pasteurization is a type of sterilization that uses heat. When it comes to American cheese, it is legally defined as a type of pasteurized processed cheese. This definition was given to American cheese under the U.S. Code of Federal Regulations. This cheese originally started out as only being white but now it is usually modified to yellow and it used on many different dishes and in many sandwiches.