Молекулярная гастрономия для креативных шеф-поваров (англ. язык) - страница 192

Молекулярная гастрономия для креативных шеф-поваров (англ. язык)

tend to join together to from a continuous network, and the milk will solidify, or “curdle”.

Furthermore, the denatured casein micelles are no longer able to prevent the denatured lactoglobulin

from coagulating, so heating milk in acid conditions will cause significant curdling. For example, if

lemon juice or vinegar are added to milk, small white particles will appear in the milk. These are due to

the casein proteins coagulating. If this mixture is then heated, the lactoglobulin proteins will also

coagulate, and the white particles become bigger and more visible as they stick together.

Making yoghurt and cheese

When bacteria contaminate milk, the bacteria degrade the lactose sugar present in the milk to produce

an acid called lactic acid. The increase in acidity will cause the casein proteins to coagulate.

Depending on the type of bacteria, this will either be desirable or undesirable. When bad bacteria

contaminate milk, the milk spoils.

When other “good” bacteria are added milk to milk to coagulate the proteins, yoghurt and cheese are

produced. The lactic acid produced by the special bacteria denatures and coagulates the milk

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proteins, and the coagulated casein network can trap within it the water and the fatty material, giving

cheese its solid form. Soft cheeses have a fairly high water content (50-75%), whereas hard cheeses

have a lower water content. When cheeses are heated, the network of coagulated proteins becomes

stronger and tighter, and eventually the liquid “trapped” within is forced out, and the cheese will

become tough.

Whipping cheese

Cheese, like cream, contains a high fat content (so a large amount of fatty acids), so theoretically it

should be able to stabilize a mousse in the same way that cream does. Cheese actually has a higher

fat content than butter, so to achieve a mousse like with cream a little extra liquid will need to be

added to the cheese mixture. If some wine is placed in a pan with a little cheese (for example

roquefort, reblochon, or goats cheese), the mixture can be slowly heated to obtain a smooth, thick and

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