In a time before refrigerators, people who lived off the land needed to preserve food. Many of the techniques we use today, such as salting and drying out meats or stewing fruits into jams, were perfected by our freezer-less ancestors. But when it came to farms with mammals and their milk, what did someone without cold storage do? Welcome our friend, cheese.
The precise history of cheese remains a mystery. While cheese has been around for thousands of years, it's hard to pinpoint the exact origin. Every culture has flavors unique to their region, but basic cheese making is all the same. The journey from cow to cheese begins with the protein casein in milk. Acid is added to "denature," or modify, the proteins on a molecular level. This turns the milk into a thickened mass in a process known as coagulation. Citric acid is commonly used and causes the milk to curdle. Once the milk is curdled and heated, a rennet is added to divide the solid curds from the liquid whey. Rennet is found in cow stomachs, but vegetable rennet also works well. Once the whey is separated from the curds, the curds are heated slowly, allowing them to be cooked and kneaded into shape. This substance -- now officially the cheese -- will be bland, so a coarse salt, or herbs and spices, and aging, all help add flavor.
To make your own cheese at home you need 30 minutes, milk and a dash of science. Mozzarella cheese is a favorite and easy cheese for first-time cooks. Cheese making is a great family activity. However, a grown-up should use the stovetop. All ingredients can be purchased online or at your local brewery supply store.
Our recipe for 30-minute mozzarella is on our website at www.carnegiesciencecenter.org/liveshows/kitchen-theater. To learn more about the science of cheese, join us at the Carnegie Science Center's Kitchen Theater for our newest program, "Say Cheese."science