How cheese is made

It is three stages, and only three

Cheesemaking comes down to setting the milk, removing the water, and waiting. Every cheese on earth passes through those three, and the variety comes from the choices made at each. Setting splits into two methods, draining decides firmness, and ageing decides aroma. So when you meet an unfamiliar cheese, three questions cover it: what set it, how much water came out, and how long has it been waiting.

First the milk is set

Add a coagulating enzyme or an acid and the proteins bind into something like a custard. Enzyme-set curd is springy; acid-set curd is crumbly. Half the cheese's character is decided right there. Enzyme-set cheese has bonds that loosen under heat, so it stretches — acid-set cheese was assembled differently and stays exactly as it is however hot the pan. That is why some cheeses refuse to melt. The cheese you can make at home by adding lemon juice to warm milk belongs squarely to the acid-set family.

Set with acid rather than rennet:

That enzyme originally came from a calf's stomach

The coagulant is called rennet, and it was traditionally taken from the fourth stomach of a milk-fed calf. Hence the oldest story about how cheese began: a trader crossing a desert carried milk in a pouch made from an animal stomach and found it curdled on arrival. Whether it happened is unknowable, but chemically it checks out exactly — enzyme, motion and warmth together will do that. Humans have been making cheese for at least seven thousand years.

Today most of it is grown in a tank

Most cheese no longer uses calf rennet. In the 1980s researchers moved the single bovine gene that codes for the enzyme into microbes, which produce it when grown in a fermenter. The US Food and Drug Administration approved it in 1990 — the first time a genetically engineered substance was permitted in food anywhere in the country. Around 90 per cent of hard cheese made in the United States is now set this way. It is cheaper, more consistent and requires no calf, so the industry moved quickly. A few protected cheeses still specify traditional rennet in their rules.

Some cheeses are set with thistle

The Iberian peninsula has a much older alternative: an infusion made from the stamens of a cardoon flower. It is old enough to appear in a first-century Roman agricultural manual as the curdling herb. Several Portuguese and Spanish sheep's-milk cheeses still work this way, and the result is unmistakable — plant enzymes break proteins somewhat differently, so the ripened interior goes soft enough to eat with a spoon and carries a faintly bitter finish. It also makes them genuinely vegetarian.

Then it is cut, and the water leaves

Cutting the set curd releases a clear liquid from every cut face. That is whey. The smaller the pieces, and the more they are heated and stirred, the more of it escapes. Whether the cheese ends up hard or soft is effectively settled here. Cut to the size of rice grains and cooked at length, it becomes a hard cheese; cut in large pieces and left alone, a soft one. How many times the maker passes a knife through the vat determines the texture years later. If cheesemaking has a decisive moment, this is it.

This is why it takes so much milk

A kilogram of hard cheese needs roughly ten litres — about two and a half US gallons — of milk, and a long-aged cheese like parmigiano takes twelve to fourteen, because most of the volume leaves as whey. That explains both the price gap between milk and cheese and why 100 grams of cheese is so nutritionally dense. For scale: a parmigiano wheel weighs about 40 kilograms, which means over 500 litres of milk went into it — and then it waits years in a store room before anyone is allowed to sell it.

These drink the most milk:

Salting and shaping

The drained curd is pressed into moulds and salted. Salt is not there for seasoning: it draws out more water, suppresses unwanted bacteria, and regulates the pace of ripening. Too little and the cheese ripens faster than anyone can control; too much and it stops altogether. Some cheeses have salt mixed through the curd, others are rubbed or floated in brine. Parmigiano sits in a salt bath for weeks, which is simply how long the salt takes to travel from the surface to the centre.

Some curd is stretched into shape

In southern Italy the curd is dipped in hot water and pulled and folded repeatedly. That aligns the proteins in one direction and creates a grain — which is why the cheese tears in strands and why it pulls into ropes on a pizza. The work has to be done by hand in scalding water, so it demanded a skilled specialist, and villages once had someone whose job it was. Even now the best mozzarella is the hand-stretched kind.

Shaped by stretching:

After that, time does the work

In the ageing room, microbes and enzymes slowly break proteins and fats into smaller pieces. Savouriness appears, aroma grows complicated, texture changes, and most of the lactose disappears. Those crunchy specks in a long-aged cheese are amino acids that crystallised out at the end of that breakdown. A few degrees of temperature or a few points of humidity change the outcome, which is why the ageing room is where a serious dairy invests its attention. In practice, the flavour of a cheese is finished in that room.

Time does the rest for these:

Where does the mould come from?

Bloomy rinds and blues are made today with cultures you buy, but they began in the wild. Roquefort came from a mould growing naturally in the limestone caves of a village in southern France, where fissures let outside air circulate and keep the temperature and humidity constant year-round — conditions that suited that particular mould exactly. Locals used to leave rye bread in the caves until it went mouldy, then dry it, grind it and stir the powder into the curd. The cultures sold in packets today are descendants of those.

Where the mould is the whole point:

You can do part of this at home

The acid-set cheeses are the easy ones. Warm milk, add lemon juice or vinegar, and curds appear within minutes; drain them in muslin and you have something close to ricotta. No enzyme, no ageing room, thirty minutes start to finish. Going further means buying rennet and cultures, which is easy enough online. Anything that needs ripening is a different matter, because holding a steady temperature and humidity for months is genuinely hard at home. Start with setting and draining. Even that much makes every cheese description you read afterwards far clearer.

This is the one you can copy at home: