Молекулярная гастрономия для креативных шеф-поваров (англ. язык) - страница 171

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

proteins of the yolks.

Use of eggs in cooking: how to make mousses

When egg whites are whisked, air bubbles are introduced. Normally, when air bubbles are introduced

into water, they do not remain stably incorporated and tend to rise and escape due to their lower

density. However, egg whites, which contain mainly water, can be whisked to produce a stable

mousse. This is due to the proteins that they contain, which are denatured on whisking, exposing their

hydrophilic and hydrophobic parts. In a similar way that they can stabilise fat water mixtures, the

hydrophobic groups on the denatured egg proteins, which do not like to interact with the surrounding

water molecules, will place themselves in contact with the air bubbles, surrounding them, leaving their

remaining hydrophilic parts to contact the water. Gradually a network of these denatured proteins is

formed around the air bubbles, and acts to keep the bubbles stably incorporated in the mixture. Not all

the proteins present in egg whites will denature on whisking. The ovalbumine proteins, which make up

the majority of the proteins in egg whites, are not denatured by vigorous beating and will only denature

under high heat.

Most proteins can however make foams. Interestingly, gelatin, when it is denatured, can also be used

to stabilize mousses. If sufficient gelatin is added to a water based liquid, the liquid can form a stable

mousse on whipping because, like denatured egg white proteins, the hydrophobic parts of the

denatured proteins will surround the air bubbles, while their hydrophilic parts stay in contact with the

surrounding water, keeping the bubbles stably incorporated in the liquid.

Such knowledge can be used to form a mousse from any non-protein containing liquid, by simply

adding gelatin.

And finally one should know that the minimum proportion of water to make foam is 5% of the foam.

The quantity of proteins is very low (some milligrams). More precisely, with enough water, one egg

III/I - 6 (of 9)

white could make about one cubic meter of foam (the maximum ever done practically was 15 liters.

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