Pasteurization is a method of cleansing milk of harmful bacteria. The milk is heated to a temperature of 161.5 degrees Fahrenheit for at least 15 seconds to kill the bacteria. The process, though, is also thought to kill beneficial bacteria that give cheeses their natural flavors and have other health benefits. In the U.S., cheese that is less than 60 days old must use pasteurized milk by law. Cheeses that are made from raw, unpasteurized milk must age for 60 days, as the harmful bacteria in the raw milk are thought to die during that time.
Fresh cheeses include ricotta, cream cheese, fresh mozzarella, cottage cheese and mascarpone. They are called fresh cheeses because they have a shelf life of about three weeks, and sometimes less. Because these cheeses are not aged, and are actually better the fresher they are, U.S. cheese makers who produce these cheeses must only use pasteurized milk.
Types of soft cheeses include Havarti, Port Salut, ricotta salata and Brie. Soft cheeses remain soft because they are aged for a maximum of 60 days, and usually less, meaning that soft cheeses produced in the U.S. must use pasteurized milk. Soft cheeses are often very smooth and creamy, melt easily and are often spreadable.
Most crème cheeses sold in the U.S. use pasteurized milk. Examples of crème cheeses include Brillat Savarin, Chaource and St. Andre. They are made using large amounts of butterfat – up to 72 percent, according to Select Cheeses. Crème cheeses do not age well because of their high fat content, which means they are better when used soon after they’re made.
Processed cheeses are the pre-packaged variety most commonly found at the supermarket. These cheeses do not require refrigeration and can keep for very long periods of time. American cheese is one common type of processed cheese. It's actually a combination of cheddar and Colby cheeses that is melted, re-formed and then packaged for consumption. Other types of processed cheese include reduced-fat cheese and Vache Qui Rit. Typically, processed cheeses must have artificial flavoring added because the processing removes most of the cheese’s natural flavors. Processed cheeses are also referred to as club cheeses or cold-pack cheeses.
Most cheeses that are specifically made for spreading are considered cheese food. Technically, they are also considered processed cheeses, and they are also commonly referred to as cold-pack cheeses. Cheese sauces fall into the category of cheese food.