The Basics of Making Cheese
The process of cheese making dates back thousands of years. Even by today's experts the process is considered to be difficult, as it combines both "Art" and "Science
Milk from different mammals such as cows, sheep's, goats and buffalo's are used to produce cheese. However, using milk from different mammals has an effect on the final quality of the cheese. For example, sheep's milk contains high total solids and thus makes the cheese harder. However, milk high in fat produces softer cheese. Therefore, the cheese process has to be modified in relation to the type of milk used.
Cheese making depends on the curdling of milk. First, the milk is carefully selected to make sure there are no antibiotics or harmful agents that could affect the process. The milk is then heated and held at a given temperature for a short period to destroy any harmful bacteria (i.e. pasteurisation).
Special starter cultures are then added to the warm milk and change a very small amount of the milk sugar into lactic acid. This acidifies the milk at a much faster rate and prepares it for the next stage. Rennet is then added to the milk and within a short time a curd is produced. The curd is then cut into small cubes, and heat is applied to start a shrinking process, which, with the steady production of lactic acid from the starter cultures, changes it into small rice-size grains.
At a carefully chosen point the curd grains are allowed to fall to the bottom of the cheese vat, the left-over liquid, which consists of water, milk sugar and albumen (now called whey) is drained off and the curd grains allowed to mat together to form large slabs of curd. The slabs are then milled, and salt is added to provide flavour and help preserve the cheese. Later, it is pressed, and subsequently packed in various size containers for maturing.
Fat exists in milk as small globules that can vary in depending on the breed of cow. The fat in the milk helps to produce flavour, aroma and body in mature cheese. Cheese made from skimmed milk is hard in body and texture, and lacks flavour. Protein exists in two forms in milk as a suspension/colloidal (casein) and in a soluble form (whey proteins).
In milk different enzymes may arise from the cow herself, from bacteria present in the teat canals or from organisms that gain entry to the milk at a later stage. Lactose is the main sugar in the milk. It provides the energy source for the starter cultures to produce lactic acid, and so helps to modify the milk for cheese making. About 10% of the lactose is used by the starter bacteria to make lactic acid, and the rest is drawn off with the whey
Cheese is really a form of fermented milk, and acid production is carried out by starter cultures. Milk being sourced from a living animal has bacteria in it when fed to the calf. Some bacteria produce acid, others help to digest the protein in the milk; some use milk as a base for their own development which, in the case of disease-producing bacteria, can infect those who drink it. Tuberculosis and undulant fever are three examples of diseases that can affect those who may drink un-pasteurised milk.
The need to clot milk has been well recognised since Roman times, and this can be achieved by the selective use of certain plants or by extracting the enzyme rennet from the fourth stomach of the milk-fed calf.
These are called textured cheese, such as Cheddar, Cheshire and the English regional cheeses including Caerphilly, which undergo pressing for a period from 18 hours up to 2-3 days after being put into the cheese moulds.
Throughout the cheese making process the starter is steadily making acid, its speed in so doing reduced somewhat in the heating process used in the final stages. To stop further acid development, and also to provide an element of flavour and help preserve the final cheese, salt is added after the curd blocks are milled. Salting provokes a further small rush of whey, cools the curd slightly and controls further acid development.
Moulding has nothing to do with the blue green mass sometimes seen on traditional cheese, or stale bread, but is the term used for containing and pressing salted curd into a certain shape in which it can be matured before finally being sold.