Cheese Making Part Two

The Basic Components of Cheese

Milk

Fat

Fat exists in milk as small globules that can vary in size 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. However, only a small amount of fat (as low as 1%) can produce a background flavour, and today's makers exploit this with their 'low-fat cheese' for which there is a growing demand.

Protein

Protein exists in two forms in milk as a suspension/colloidal (casein) and in a soluble form (whey proteins). As an analogy, however, consider the first type of protein as a densely woven mesh rather like a string vest suspended freely in the aqueous phase of milk. As long as the milk remains sweet, this structure is unaffected and the milk remains totally fluid. However, if the milk acidifies (i.e. goes sour) without the presence of coagulating enzymes the structure changes quite suddenly at the 'iso-electric point', and a fragile curd is formed that collapses with the slightest agitation into tiny fragments. A typical example is the fine mass we see when milk sours naturally. By adding rennet, at just the right time before the milk would go completely sour, the structure of the casein is changed radically to form a solid curd called para-casein. This can then be cut with knives and saved to be collected as grains of curd for subsequent processing.

The second fraction of protein is called albumen (alpha-lactalbumin and beta-lactoglobulin). This as described above passes out with the whey and is usually lost, though it can be recovered by specialised and expensive filtration methods. When hot milk is allowed to stand still for any time, whey proteins appear as a 'skin' on the surface.

Enzymes

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. As we shall see shortly these enzymes have a profound effect on the quality of raw milk, and the ripening of cheese in the store. For example, lipases, proteases and lactase enzymes hydrolyse the fat, protein and lactose respectively into different components. In this case, these enzymes, which occur naturally in the milk or which are sometimes supplied by the indigenous bacteria in the milk and the added starter culture, can change the milk fats and proteins in the process of ripening the cheese to produce the delicate flavours and aromas

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