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. 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.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.
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
.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.The cheeses are turned regularly. Most Dutch cheese must, by law, be matured for at least four weeks.
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