Молекулярная гастрономия для креативных шеф-поваров (англ. язык) - страница 168

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

In order to prevent raw egg white from leaving the egg by the prick when boiling pricked eggs or from

any cracks that form in the eggshell during boiling, vinegar is often added to the boiling water. Vinegar

will cause any egg white proteins that leave the egg via the prick or the crack to coagulate sufficiently

rapidly (see above explanation) to form a “plug” in the prick or crack, sealing the rest of the egg inside

the shell.

The age of the egg affects coagulation temperatures and therefore cooking times. As eggs get older,

carbon dioxide (which is weakly acidic) leaks out through the small pores in the shell, making the egg

white less acidic, so coagulation of the proteins will take longer (less charged H+ ions to act as

bridges) and cooking takes longer.


Eggs are usually poached in water with vinegar. Because vinegar is acidic (it is a solution of many

percent of acetic acid, plus other acids such as malic acid), it contains a high number of positively

charged H+ ions. Dropping an egg in water containing such H+ ions will cause the outside of the egg,

which is in direct contact with the H+ ions, to coagulate and solidify rapidly, which will ensure the egg

stays whole during poaching. As explained above, in addition to reducing repulsion between

denatured proteins, H+ ions help break the bonds holding the folded proteins initially together,

increasing the formation of the denatured proteins.

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The part of the egg white in contact with the yolk tends to stay more liquid during frying an egg as the

rest of the white solidifies, which does not produce a very appetizing egg. To prevent the outside of a

fried egg from becoming too rubbery while these inner parts solidify, it is often suggested to salt the

part of the egg white in contact with the yolk to speed up the coagulation of these parts, reducing

overall cooking time and thus the drying out of the rest of the egg white. The yolk however should not

be salted – it favours the undesired hardening of the yolk.

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