by Margaret Dedloff
We eat cheese as a snack, we put it on our pasta and our pizza, we even spread it on our bagels! Cheese is everywhere, and the average American eats 35 pounds of cheese per year. But how is this delicious food made?
Cheese starts with a really simple ingredient: milk! Cheese can be made from cow’s milk, sheep’s milk, goat’s milk, or even water buffalo milk. The type of milk used to make the cheese can alter the flavor. Goat and sheep’s milk makes cheese more tangy than cow’s milk. The animal’s diet changes the flavor and protein content of their milk, which can then change the properties of the cheese.
Beneficial bacteria are added to the milk to make it acidic. The bacteria break down lactose, the sugar in milk, in a process called fermentation. Fermentation produces lactic acid, which makes the milk even more acidic.
While the bacteria are breaking down the lactose, the cheesemakers will heat the milk. Ultimately, as the milk warms and becomes more acidic, it will start to coagulate. This process forms milk solids called curds. The remaining liquid is whey.
Sometimes, cheesemakers add rennet, a mix of enzymes that comes from the stomach linings of calves, to help speed up the curd forming process. Rennet contains rennin, which converts caseinogen to casein. Caseinogen can dissolve in water, while casein cannot. The formation of casein makes curds form faster.
The speed that acidification occurs and how quickly curds are formed changes the properties of the cheese. Making Swiss cheese requires faster curd formation than softer cheeses, like cream cheese. Altering the amount of rennet and type of bacteria in the starting culture allows the cheesemaker to change the taste and texture of the cheese.
After their formation, curds are pressed to release the remaining whey and to be made into a solid block. From here, some cheeses can be sent straight to the store. Other cheeses have to undergo a process called ripening, or aging. Cheeses can age anywhere between a few months to several years. For example, muenster ages for 5 to 7 weeks, but parmesan ages 10 to 24 weeks. When cheese ages in a cool, dry place, bacteria will further break down the proteins in the cheese. This process results in the formation of different flavors and textures.
Cheesemakers can also change the flavor of their cheese by introducing different things during the aging process. For example, some cheeses are exposed to specific types of mold while aging. Camembert, a soft, creamy cheese from France, is exposed to Penicillium camemberti on its surface. P. camemberti gives camembert its trademark mushroomy flavor. While camembert has mold added to its surface, blue cheese gets injected with a mold called Penicillium roqueforti. Some cheeses, like Limburger, the famous stinky cheese, are washed during the aging process with beer, liquor or water. This process was originally done to prevent mold growth, but it resulted in growth of a bacterium called Brevibacterium linens, which makes the cheese very smelly.
Cheesemaking can be as simple or as complex as the cheesemaker desires. Many of the steps can be altered to make the variety of tastes and textures that we love. You can even make cheese at home!
