Good cheese begins with good milk. Cheesemakers warm a vat of milk and add a cheese culture. The culture is a specific bacterium that chemically acidifies the milk, transforming lactose (milk sugar) into lactic acid and causing the milk to curdle. When the pH reaches the desired level, the cheesemaker will add rennet. Rennet originally derived from the lining of a calf’s stomach, although only the most traditional creameries still use animal rennet. Most modern cheesemakers use a laboratory-grown, vegetable-based rennet. To distinguish this substance from animal rennet, some cheesemakers use the term microbial enzymes, and they perform the same function, which is to bind the milk proteins together, separating the milk solids (curds) from the liquid whey.

What the cheesemaker does next depends on what kind of cheese is being made. Except with the softer cheeses, something must be done to extract more whey from the developing cheese. If the cheese is a Cheddar, for example, the curd will be sliced, stacked, and pressed together, in a process called “cheddaring.” If it’s a Swiss cheese, it will be gently heated again, or “cooked.”  The goal is the same—to result in a firmer curd—but the texture of the resulting cheese will be quite different.

Finally, the cheese will be aged, or cured. Again, the cheesemaker will employ different methods based on the type of cheese being made. A soft-ripened cheese like Brie, for instance, will be sprayed on its surface with a particular type of mold, which will work from the outside of the cheese toward its center, chemically breaking down the components of the cheese and making its flavors more complex. A washed-rind cheese like Morbier or Alsatian Munster will be rubbed down two or three times daily with a solution of brine or some other liquid, often alcoholic. The purpose is to encourage a certain type of bacterial growth, and to stop other kinds. The result, as anyone who has nosed this family of cheeses, is quite stinky. A cheese like English farmhouse Cheddar will be wrapped with a cloth and left in a dark, humid, cave-like environment, sometimes for years.