Thomas Zeravsky, age 7, of Allentown, Pennsylvania, for his question:
How do they make cheese?
Cheese is made from milk and it takes time to change the milky white liquid into solid cheesy chunks and slices. The cheese is older than the milk and some cheese reaches the age of two years. As it ages, the cheese is changed by tiny tiny living things called bacteria.
People learned to make cheeses thousands of year8 ago. Sumo at our ancestors discovered how to change milk into cheese before they learned how to cook meat and vegetables. Perhaps they discovered the trick by accident. Mothers of long ago took milk for their growing children from cows and goats, sheep and camels. The fresh milk was sweet arid tasty and very nourishing. But the milk did not stay fresh very long. It curdled and went sour. Once in a while, a pot of curdled milk was forgotten and left perhaps in a cool cave. Months ;. later, somebody found it again and behold, the curdled milk had changed to solid cheese. It changed as it aged and grew older.
Cheese makers around the world have recipes for more than 400 different kinds of cheeses. We can buy soft cottage cheeses and hard yellow cheeses and creamy blue cheeses that are neither very hard nor very soft. There are mild cheeses with quiet flavors, cheeses with sharp, peppy flavors and cheeses that have strong, tangy tastes. The cheese makers of long ago learned that a cheese changes as it ages and grows older. It takes time to grow firm and more time to get its sharp, tangy taste.
It takes only a few days for milk to change into soft, creamy cottage cheese. But ft takes the milk six months to become mild hard, yellow cheese. In mother six months, it gets a stronger, cheesy flavor. If it is left to age for two whole years, the yellow cheese is rich and crunchy, sharp and tangy. It ripens with age all by itself and the cheese m4ers cannot force it to hurry. Modern cheese makers leave their cheeses to age in cool, breeze rooms. The first cheeses were left to age in cool, breezy caves.
A few hundred years ago, people discovered how milk changes itself into cheese. The microscope was invented. Its spy glass enlarged objects that were too small far human eyes to see. The experts discovered that we share our world with ell sorts of tiny living bacteria. These teeming midgets are everywhere. And some varieties are very fond of milk.
Ordinary fresh milk is a watery mixture of floating fragments of fat and rich proteins, vitamins and other nourishing chemicals. Certain kinds of bacteria thrive on these milky fragments. As they thrive and multiply in sour milk, they change it into cheese. In time, these busy bacteria cause the cheese to age and ripen with its own rich flavor.
There are thousands of different bacteria but only a few hundred types can change milk into cheese. Experts package the cheese making bacteria in germ free cultures. Each type creates its own special kind of cheese. To make hard, yellow cheese, a culture of the right bacteria is blended with the soured milk. Then the mixture is left alone while the busy bacteria do their work.
A modern dairy is extra clean and cheese making is kept germfree from start to finish. The fresh milk is pasteurized to destroy all the harmful microbes. The solid cheeses are left to age in spotlessly clean, air cooled roams. Cheese makers call this the curing process. It takes almost five quarts of milk to make a pound of solid yellow cheddar cheese. After six months of curing, the cheese will be firm and mild. If the cheese is left alone for two years, the busy bacteria will change it into crumbly cheddar with a sharp, tangy flavor.