🔄 How cheese is made

Cheese is made by coagulating the milk protein casein and separating the liquid whey from the curd; the curd is then shaped, salted and, for most kinds, left to ripen. The Codex Alimentarius standard CXS 283-1978 defines cheese as a ripened or unripened product obtained by coagulating milk proteins with rennet or other suitable coagulating agents and partly draining the whey.

The raw material is milk: cow's milk, sheep's milk, goat's milk or buffalo milk, raw or pasteurised. First a starter culture is added — lactic acid bacteria that turn lactose into lactic acid. Then comes rennet: its main enzyme, chymosin, acts on casein, and at around 30–35 °C the milk sets into a firm gel within roughly half an hour to an hour. This step is called coagulation.

Next the curd is cut: small grains release more whey and give a hard cheese, large ones a soft cheese. The grains are stirred and sometimes heated (to about 55 °C for Parmigiano Reggiano), the whey is drained, and the curd is moulded and pressed. Salt is mixed into the curd, rubbed onto the rind or added by soaking the wheels in brine; it shapes flavour and rind and holds back unwanted microbes. The last stage is ripening in a cellar or chamber: a few weeks for camembert, 12 months or more for Parmigiano Reggiano.

There are other routes too. Fresh acid-set cheeses such as quark-style curd cheese and paneer are coagulated with acid and no rennet, ricotta is made by heating whey, and mozzarella and sulguni are stretched in hot water. All these steps are carried out by a cheesemaker in a farm, artisan or industrial cheese dairy.

Why it matters to you: knowing the process makes labels easier to read (raw or pasteurised milk, type of coagulant, ripening time), explains why hard cheese keeps longer than fresh cheese, and helps you choose vegetarian cheese made with microbial coagulant instead of animal rennet.