Молекулярная гастрономия для креативных шеф-поваров (англ. язык) - страница 159

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

merely to make the fat droplets smaller and improve their dispersion, but a constant whisking

will prevent the temperature of the mayonnaise from getting too low, especially if the emulsion

is not heated, so will reduce the chances of fat droplets congealing. Ingredients to be used in

an emulsion should also be removed from the fridge in advance of preparing the emulsion, to

further eliminate this problem.

V/I - 3 (of 5)

Emulsions made with egg yolks

These emulsions contain proteins and phosholipids from the egg yolk, which act to stabilise a mixture

of water and fat.

Egg freshness:

Eggs used for egg based emulsions should be fresh - when eggs age, their phospholipid molecules

decompose into molecules of cholesterol. Cholesterol is not as good an emulsifier, because it does not

contain a pronounced charged region like in a phospholipid, so is less likely to stabilise the

incorporated fat droplets.

Presence of acid:

Acid is often added to emulsions containing phospholipids: - in an acidic medium, the presence of the

H+ ions between the fat droplets reduces the chances that the charged phosphate heads, which

extend from the fat droplets, will contact each other. Without acid, the surrounded fat droplets are less

likely to repel each other and the emulsion will be more likely to separate out.

Acidity also play an important role on protein structure. As proteins are probably more important than

phospholipids in emulsion...

y to separate out.

Acidity also play an important role on protein structure. As proteins are probably more important than

phospholipids in emulsion making, acidity is important.

The exemplary mayonnaise

To make a mayonnaise, egg yolk is mixed with vinegar, salt and pepper. The water phase of the

mayonnaise is provided by the vinegar (which contains 80 % water) and the egg yolk (which contains

almost 50% water). The egg yolks main function is to provide a generous source of proteins and

phospholipids.

As the oil is added, it is progressively introduced into the centre of the phospholipids micelles, and this

results in fat droplets that are surrounded by phospholipid membranes and are therefore very stably

dispersed in the water phase. At the same time, proteins denatured through whisking surround the oil

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