From milk to cheese
It all starts with milk, which is defined as “the physiological excretion or secretion from the mammary gland obtained through the ongoing, regular milking of properly fed and healthy animals that are lactating correctly”. Milk is an emulsion of fats in water that also contains a mixture of suspended and dissolved proteins, enzymes, minerals, vitamins, characteristic microorganisms and certain gases.
From milk to cheese in 10 steps.
The production process
Cheese is obtained from either full-fat or skimmed milk through the coagulation of the main protein component, casein. From the two main methods of coagulation (lactic-acid and rennet) it is possible to achieve hugely different end products. Lactic-acid coagulation relies on a sharp increase in acidity (to a pH as low as 4.4 in some cases). This occurs spontaneously in the milk as a by-product of the fermentation effected by lactic acid bacteria, which produces lactic acid. The acidity destabilises the casein, which then naturally clumps together to form a crumbly “coagulum”. This lacks many of the minerals found in the milk but, by way of compensation, retains most of the protein and fat. In rennet coagulation, the basic process is achieved by enzymes (the “rennet”). These are able to “cut” certain parts of the casein particles, causing the casein to destabilise and precipitate into a “curd”, which squeezes out the liquid whey as it spontaneously contracts. After the coagulation phases, the cheesemaking process can include: mechanical cutting of the curd to facilitate the release of some of the remaining liquid whey; “cooking” the curds (for the production of hard and semi-hard cheeses with a lower water content and longer shelf-life); “stewing”, during which the cheese is kept at a temperature above 20°C; and ageing or maturing (in a cool, humid environment), during which certain elements in the “paste” of the cheese are transformed by a series of biochemical processes, producing the flavours, textures and aromas that make each cheese unique.