The process of making cheese is often described as part art, and part science – and for good reason. There are hundreds of distinct cheese varieties produced around the world today, and all are made with varying recipes, techniques, and trade secrets. Just think of how soft, creamy Brie differs from firm, salty Parmesan. Or how lacy Baby Swiss is so much more delicate than sharp, aged Cheddar.
Despite all their delicious deviations, all varieties of natural cheese go from dairy farm to our ham sandwiches and hors d’oeuvre platters by undergoing the same essential process. To see this process at work most simply, we needn’t do more than look back to cheese’s origins.
Though no one knows for sure when cheese was first made, many believe a nomadic Arab created it by accident while carrying a saddlebag full of milk on his horse. The hot sun and galloping movement caused the milk to ferment, turning it into simple curds and whey.
Of course the process of making cheese has become much more sophisticated over these many thousands of years. But once the milk has been prepared, all cheeses are crafted using some variance of the same four-step process:
Liquid milk is the main raw material cheese makers work with, and it can come from any variety of mammal sources, including cows, sheep, goats, water buffalo, and even camels and reindeer. The breeds, feed, milking cycles and transportation methods dairy farmers choose to use can all affect the flavour of the milk, and ultimately, the cheese made from it.
While many modern dairies now pasteurise milk sold to large cheese factories, there is some disagreement in the field as to whether this is necessary. In fact, most cheese connoisseurs will tell you the best cheeses are the old-fashioned kinds made from milk in its raw, natural, unpasteurised state.
Step 1: Curdling
After the milk is prepared, it is curdled to separate the solid components (curds) from the liquid components (whey). To do this, cheese makers usually add a lactic starter, rennet, or both, depending on the type of cheese being made.
A lactic starter is used when making soft “fresh” cheeses like cottage cheese and ricotta. This special strain of lactic acid bacteria causes milk to separate into small grains of curd.
Rennet is employed when making firm or semi-firm cheeses such as Raclette and Tomme. This enzyme, which traditionally comes from the lining of a calf’s stomach, causes the milk to separate into larger grains of curd. Today, many cheeses are made with synthetic or “vegetarian” rennet produced from fig leaves, artichokes or melons.
When lactic starter and rennet are used together, they produce cheeses that display a combination of both soft and firm characteristics. The best examples of these are semi-soft or semi-crumbly cheeses like Camembert, Munster and many of the blue-veined varieties.
Step 2: Draining
Draining involves further removing the whey to obtain the desired moisture content for the cheese being made. As the curd is allowed to rest or “set up,” the acidity levels rise, the bacteria multiply and the unique flavour of the cheese begins to develop.
It is at this point that cheese making recipes begin to greatly diverge in technique. In a technique called “stretching,” for example, the curd is stretched and kneaded in hot water to make stringy, pulled cheeses like Mozzarella and Provolone.
Step 3: Pressing
Most cheeses attain their final shape and size when the curds are pressed into forms or moulds. These moulds are designed to expel moisture, so cheeses subjected to more pressure turn out drier and firmer. Finely textured Cheddar, for example, might be pressed for up to three days, while a more crumbly Cheshire might be pressed for only 24 hours.
During this stage, it is also common for cheeses to be further treated with various ingredients such as salt, herbs, or food colourings. They may also be smoked, covered in brine baths or ashes, or inoculated with bacterial moulds. The most famous of these is Penicillium roqueforti used to make bold blue cheeses like Roquefort and Stilton.
Step 4: Ripening
Once a cheese has been curdled, drained, and pressed, the process of ripening, or maturation can begin. During this process, expert cheese agers (affineurs) closely monitor moisture, temperature and oxygen, all of which influence microbes in the cheese to slowly create its unique and specific texture, flavour and aroma.
For soft, fresh cheeses, the ripening process may last only a few hours or days, but for long-aged cheeses it may go on for several months or more. The undeniably intense Parmigiano Reggiano from Italy is aged two full years before it is sold.