You Asked:
How is cheese made? — Sam, West Lafayette, Ind.

Marshall Answered:
Cheese is a way to preserve milk. The basic idea behind cheese is to take milk and eliminate most of the water and sugars so that the protein and fats are preserved.

You start with milk and add rennet and bacteria to curdle it. Protein and fat bind together to form the curds, while water, lactose and a little protein form the whey. The cheese maker drains off the whey and presses the curds together. After aging, the curds become cheese.

The type of bacteria you add (along with how you process the cheese during aging) determines the type of cheese you get. Swiss cheese, for example, contains one type of bacteria called Propionibacter that produces carbon dioxide gas to create the holes. Blue cheese contains a type of penicillium that creates the blue coloring and the flavor.

This video shows you the production of cheese in a factory setting:

For more info see: How Cheese Works