Man has domesticated milk-producing animals for many thousands of years and ever since then we have known of the propensity of milk to separate into curds and whey. Curds are lumps of phosphoprotein and whey is a watery fluid containing lactose, minerals, vitamins and traces of fat. When milk sours, it coagulates, and the curds and whey separate. This process is called curdling. It is from the curds that cheese is made. In fact, the first and simplest form of cheese was made simply by draining and pressing these curds and adding salt.
 Making Cheese
The styles of cheese depend on the type of animal milk used; usually cow, goat, sheep, buffalo, camel, yak and reindeer milk is used. Often two types of milk are combined to make cheese. The taste and texture of the cheese also depends on the butter-fat content of the milk, i.e., whole milk, skimmed milk or low-fat milk. Nowadays, mostly pasteurised milk is used; however, there are a few European varieties that still use raw milk. In most countries, however, the use of raw milk is prohibited due to food safety regulations.
A big discovery in the history of cheese making was the usage of rennets to accelerate the process of curdling milk. Rennets are naturally occurring, complex enzymes found in the stomach of all young mammals to digest their mothers’ milk. The active ingredient in rennet is called rennin or chymosin and the best source of this is the ‘abomasum’ or fourth stomach of suckling calves. It also made from sheep and goats. See RENNET FOR MAKING CHEESE
A few cheeses, also called ‘false cheeses’, are made with the addition of acidic substances, such as lemon juice or vinegar, instead of rennet. The Indian paneer, similar to cottage cheese, is made using this method. This cheese is suitable for vegetarians.
 Vegetarian Cheese
These days, there are also ‘vegetarian cheeses’. Some vegetables, such as fig tree bark, thistles and nettles, have been found to have coagulating properties. However, for vegetarian cheese-making, usually microbial rennet or genetically engineered rennet is used. Microbial rennets are enzymes made from molds grown in a fermenter. By using calf-genes, scientists have been able to modify some bacteria, fungus or yeasts to produce chymosin. This synthetically produced enzyme is then used to make cheese. Both microbial rennet and genetically engineered rennet are suitable for vegetarians. The most commonly available vegetarian cheeses are made from rennet produced by a fungus named Mucor miehei.
Once the milk is heated, and the rennet is added to the milk, the curdling process begins. Often, other chemicals may also be added to the cheese to improve the curdling process (calcium chloride) and to limit bacteria that may contaminate the cheese (potassium nitrate).
After the curdling process, the curds are cut and drained of the whey. The size of cut and the method of draining vary with different types of cheeses. Cheeses with a soft texture are sparingly cut and allowed to drain naturally. For harder cheeses, the curds are heated so that more whey can be drained out.
After this separation process, the curds are cut and placed into vats for pressing. Once pressed, the cheeses can be treated in a number of ways. Firstly, they are placed into moulds. From here on, the process becomes more complicated, as many varieties of cheese are then aged and ripened in a process called curing. Soft cheeses, such as cottage cheese, are not aged. However, hundreds of varieties of cheese are cured. Curing is the ageing and ripening of cheese according to specific conditions and treatment of temperature, storage and sanitation. See Wisconsin Cheese
 Curing and Flavouring
At the curing stage, the cheese is placed in moulds that are flavoured, or in brine; some may be covered in herbs and spices or washed in alcohol. They are then stored in precise temperature and humidity conditions and allowed to ripen. The amount of time allowed for maturity also varies from a few weeks to a number of years. This allows the flavours to develop, and also gives the cheese certain characteristics—depending on the method, some cheeses develop veins, holes, crusts and rinds.
Some cheeses develop a rind naturally; others are sprayed with bacteria to form the rind. Cheeses may also be washed to encourage certain bacterial growth. Cheese is often stored in cloth or wax. The storage of cheese also depends on the variety of cheese. Many cheeses are produced for sale in different countries and this also affects the storage and packaging of the cheese
Practically every culture in the world has developed a unique method of making cheese, the only major exceptions being China and the Ancient Americas. There are literally hundreds of varieties of cheese available today, and each type has a special method of preparation. France, Italy, Switzerland and England are particularly well known for their many varieties of cheese.
A fairly exhaustive list of the varieties of cheese, classified by country of origin, milk, texture and name is available at Cheese.com.
 References and Sources
- RENNET FOR MAKING CHEESE
- Wisconsin Cheese
- Vegetarian Society
- The Gourmet Food and Cooking Resource
- Making Cheese at Home
- CHEESE MAKING ILLUSTRATED