are not reversible).
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Figure 5. A model of egg white coagulation. Many proteins of egg whites are coiled, because
the inner part is hydrophobic; being dissolved in water (egg white contains 90% water), the
proteins coil spontaneously, so that hydrophilic parts are in water, as hydrophobic parts are
buried. When heated, the energy of movement of the molecules induces an uncoiling of
proteins (“denaturation”) and, subsequently, a coagulation of egg whites, due to chemical links
between uncoiled proteins (bottom). Of course, such description is simplified, as, in particular,
proteins do not extend like threads.
How much does this theory hold? An experimental check is to ask the question: why are proteins
coiled? The answer is: because they are in water. Therefore in something else than water, they
should coil differently and perhaps coagulate also.
Let’s make the experiment of adding ethanol to an egg white: when the ethanol concentration is
enough, egg white coagulates. Of course, this can be done with something else than ethanol, such as
vodka, or cognac…
Let’s go on with experimental tests. What if acid were added to egg white? Is it true that acids “cook”
fish, like in fishes “a la Tahitienne”, or in cebiche? Of course, there are theoretical reasons to get a
result, as proteins have some amino acids residues whose electric charge depends on pH (a measure
of acidity or alkalinity, between 0 and 14). And when an egg is put into vinegar, there is first dissolution
of the shell, then a slow coagulation of the egg, producing a strange egg, after about one month. As
“one century years old eggs” are obtained in China by putting eggs in a mixture of clay, straw and lime
or ashes (containing potash, i.e. an alkali), we called our “acid cooked” eggs “minus one century years
Are they “cooked”? Not if we follow to the definition given by the dictionary, according to which cooking
is a transformation induced by heat. This is why, in France, after an email poll for more than 1300