How Cheese is Made

ALTHOUGH EACH type of cheese is made according to its own detailed recipe, there are a number of broad techniques and methods that all cheesemakers follow, regardless of the kind of cheese they’re making. Like beer, love, and other mysteries, chemical reactions create cheese. This involves sugars, proteins, enzymes, and many other things you forget from high school biology class.

It’s not so difficult to understand, really. All cheese starts with some mammal’s milk, the fresher the better. From there, it is all about “controlled spoilage,” as the great cheese writer Steven Jenkins put it. Or, if you prefer Miss Muffett, minding your curds and whey.  

First stage: Curd Production
The first thing a cheesemaker does is to fill a vessel with milk. The liquid is then warmed, and a starter culture is added (streptococci and lactobacilli, for those taking notes).

The starter converts the natural sugars in milk (lactose) into lactic acid. This equalizes the acid levels (pH), which is essential to a controlled coagulation. A substance called rennet, containing the enzyme rennin, is next added to the mixture. The rennet causes the proteins in the milk (casein) to clump together. The resulting solids form the curd, while the residual milky liquid is the whey.

Historically, the rennet came from the stomach lining of animals: goats for chevre, sheep for feta, and so forth. This is still the traditional process, but in recent years, many producers have opted to use super-concentrated vegetable rennet, because it’s easier to work with and more reliable than animal varieties.

Once the curd mixture is formed, it is left to settle for a period of thirty minutes to two hours, depending on how congealed the cheesemaker wants it to become. As the curd sets, the temperature in the air plays a factor. Generally speaking, low temperatures produce the proper curd consistency for soft cheeses, while a medium temperature yields the firmest curd. A hot room makes the curd rubbery, which is needed for semi-hard cheeses.

Second Stage: Curd Concentration
Different varieties require different consistencies of curd, but at its essence cheese is made by separating some volume of whey liquid and air from some volume of solids. Concentrating methods include cooking, pressing, salting, and more.

In most cases, the curd is cut during the second stage, as a way to rid the mixture of whey. The size of the cut depends on the kind of cheese being made. The finer the cut, the harder the cheese. (Since cutting gets rid of liquids, if you cut the curd into tiny pieces, most of the whey is removed.) Conversely, some cheeses–notably many made from goat’s or sheep’s milk–aren’t cut at all.

One family of cheeses, which includes Colby, Cheshire and others of the ilk, is subjected to cheddaring. In this, the curds are piled up, then cut, then the process is repeated until almost all of the whey drains off. The resulting curds are then pushed through a grinding mill, and become tiny pieces ready to be pressed into a mold and aged.

Remember that making cheese is all about turning milk into solid form, with specific tastes, odor, and texture. That involves a number of chemical reactions; as the cheesemaker works with the curds and whey, the steps taken control those reactions to produce the desired result.

The salting step is therefore essential. Salt naturally dehydrates everything it touches, so adding it to the cut curds allows the maker to control the rate at which the cheese will ripen.
 
Salt is added in different ways. The cheese may be soaked in saltwater (Emmental); its outside may be rubbed with salt particles (Parmigiano) or with a brine-soaked cloth (Taleggio); or the salt may be put right into the curd (Cheddar).

After salting, the cheese is shaped, generally by being pressed into a mold, removing still more of the whey. Dryness and hardness are a function of how much residual liquid and air are in the cheese, which depends on how forcefully you press it.

Third Stage: Ripening
Cheese, like wine, generally improves with age, up until a certain point. During this part of the process, the sugars, fats, and proteins in the cheese are breaking down naturally. Eventually, when the cheese reaches the desired ripeness, you have a proper cheese.

There’s more to it than that, of course. Temperature, humidity, exposed surface area, and other factors come into play.

Some cheeses ripen from the rind inward, others just the reverse. Soft varieties ripen quickly, since they retain more liquid than harder ones. Lower temperatures slow the process a bit.

Harder cheeses ripen more leisurely, and require somewhat different handling as a result. As cheddar ages, for example, the fats within it shift slowly. In order to distribute the fat evenly in the finished product, aging cheddar involves regularly turning the rounds as they ripen.

Many of the features that define various cheeses arise during aging. Swiss cheeses like Emmental get their holes from the bacteria in the starter. As the cheese ripens, the bacteria trigger a reaction that causes the cheese to contract in certain areas, creating holes in other places.

Blue cheeses, like Roquefort, get their veins during aging, just like people. The cheese maker pokes holes in the stuff as it ripens, to introduce oxygen inside. Upon meeting up with the oxygen, the particular bacterium forms that trademark mold.

Some particularly pungent cheeses (think of Munster) undergo a rind-washing process to ripen. The soft cheese’s outside is rubbed with, or soaked in, some flavored liquid: saltwater, beer, wine, or spirits. The liquid reacts with the bacteria in the cheese to create its unique taste and odor.