Молекулярная гастрономия для креативных шеф-поваров (англ. язык) - страница 167

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

livetine alpha 70°C

livetine beta 80°C

livetine gamma 62°C

Phosvitine More than 140°C

total 65-70°C (because of LDL)


When an egg is placed in boiling water, heat from the surrounding boiling water passes into the egg

and heats it up. This causes the egg white proteins to begin to coagulate. After about three minutes,

the temperature at the core of the egg will not be high enough to cause the egg yolk proteins to

coagulate, so the yolk will remain fairly liquid, whereas in the egg white will solidify but the gel would

not have started to squeeze any water out. If the egg is removed at this point, a “soft boiled egg” is

produced – the yolk is still liquid; the white solid, but not rubbery.

If the egg is heated for longer, the egg temperature reaches high enough to allow the yolk proteins to

coagulate, thus producing the common “hard boiled egg”.

Heating even longer than the recommended “8 minutes” may cause the egg white proteins to degrade,

which will break down and release a nauseous gas called hydrogen sulfide. Iron, which is present in

the egg yolk, may react with the released gas to produce ferrous sulphide (a green-gray solid). This

explains why overcooked eggs often have a funny “eggy” smell (he hydrogen sulphide), and slightly

green-colored yolks.

Fe2+ + H2S _ FeS

(Iron) from degraded proteins (Iron sulphide)

It is often recommended to prick an egg with a pin at the larger end of the egg if it is to be boiled

before it is cooked. This larger end of the egg contains a small air space (whose volume depends on

the freshness of the egg), and pricking provides an escape route for the contained air before the egg

white proteins begin to take their form as they coagulate, so a perfectly rounded egg is produced. The

air cannot escape so rapidly when un-pricked eggs are boiled, and the proteins will start to coagulate

around the air space so a flattened egg is produced. It is also thought that the expansions of this built

up air may contribute to the cracking of egg shells often observed on boiling.

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