Concept: Cheese - The process

The process of cheese making

Cheese consists of proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. It is produced by coagulation of the milk protein casein. Typically, the milk is acidified and addition of the enzyme rennetcauses coagulation. The solids are separated and pressed into final form. Some cheeses have molds on the rind or throughout. Most cheeses melt at cooking temperature.

Coagulation: Curds are a dairy product obtained by curdling (coagulating) milk with rennet or an edible acidic substance such as lemon juiceor vinegar, and then draining off the liquid portion. The increased acidity causes the milk proteins (casein) to tangle into solid masses, or curds. The remaining liquid, which contains only whey proteins, is the whey. In cow's milk, 80% of the proteins are caseins. Milk that has been left to sour (raw milk alone or pasteurized milk with added lactic acid bacteria or yeast) will also naturally produce curds, and sour milk cheese is produced this way.

Cheese making, Step by Step

1. To curdle the milk, rennet and a coagulant are added. The lactic bacteria converts lactose (milk sugar) into lactic acid and this lowers the degree of acidity (pH) of the milk. Harmful bacteria are thus destroyed. To make the milk curdle, use is made of an extract from the stomachs of calves. This extract contains the enzyme `chymosin'. This enzyme ensures that the proteins in milk (casein-proteins), which normally float in lumps (micelles) coagulate. Usually they reject each other, because they are charged and the lumps coagulate or adhere together. As well as rennet and the coagulant, other substances are also added to the milk. For instance calcium salts, which speed up the curdling process and a small, carefully controlled quantity of saltpetre (nitrate) to restrain the growth of harmful butyric acid bacteria. A partial alternative is bactofuging the milk which is the seperating of the bacteria and their spores from the milk by means of the bactofuge. 

2. When curdling has been completed, the milk-mass is cut which enables the whey to discharge more easily. After cutting, part of the whey is drained and warm water added. Because of the increased temperature, more liquid discharges. When the curd is sufficiently solid it is transferred to moulds and the cheese is pressed into its final shape. 

3. During and after moulding, the process of `souring' within the cheese continues. In the creamery the cheese remains in the mould for an additional hour or so.

4. Then the cheese is submerged in a brine bath. The salt gives the cheese its savoury taste and inhibits the growth of undesirable bacteria which can also affect the flavour. Whilst the cheese is maturing the long molecules break down, especially those of the lactoprotein. In addition carbon dioxide is formed, which causes the `holes' in the cheeses which professionals call `eyes'. Some cheeses have extra large holes due to the addition of propionic acid which also gives the sweet, nutty flavour. 

5. During the maturing, the cheeses are provided at regular intervals with a thin coat of plastic which protects the rind against the formation of mould. The rind of some types, such as Dutch Fougerond and Kernhem, are rubbed with a bacteria during maturing. 

6. The cheeses are turned regularly.

7. Most Dutch cheese must, by law, be matured for at least four weeks.