How is cheese made?
Cheese is made by curdling milk with bacteria and an enzyme called rennet, separating the solid curds from the liquid whey, then salting, shaping and often aging the curds.
First, milk is warmed and starter bacteria are added. The bacteria turn lactose, the sugar in milk, into lactic acid, which begins to sour the milk and develop flavor. Then rennet is added, causing the milk proteins to clump together into a soft gel. The gel is cut into small pieces to release the liquid whey.
The curds are stirred, heated and drained. Depending on the cheese, they may be pressed, salted, stretched or washed. They are then shaped in molds. Fresh cheeses, like ricotta and cottage cheese, are eaten soon. Others are aged for weeks, months or years, during which bacteria and molds develop flavor and texture.
What makes cheeses different
The type of milk, the bacteria and molds used, the temperature, the amount of pressing and the length of aging all change the result. Blue cheeses have mold injected or added, Swiss cheeses get holes from gas made by bacteria and brie develops a soft white rind.
Did You Know?
According to legend, cheese was discovered when milk was stored in a pouch made from an animal's stomach, which contains natural rennet.