people, we decided for the new word “coction”, to describe non thermal induced coagulation.
Finally is the coagulation theory true? Not completely, as it is only a theory. It does not explain, in
particular, why hard boiled eggs are tender when cooked less than 10 minutes, and why they have a
rubbery white when cooked longer.
The theory is not precise enough to explain this fact: we have to use a more complex explanation,
considering that egg whites are made of a lot of proteins, having each a special denaturation
temperature. The first one, for ovotransferrin, is 61°C: at this stage, the egg white should be very
tender because only one net is trapping water molecules. At temperatures higher than 70°C, other
proteins coagulate, making a second gel in the first, the consistency becomes harder, etc. As the yolk
is concerned, the first transition is about 70°C.
Hence the question: what would we get if we cook an egg at only 65°C? The result is a very
interesting egg, whose consistency does not depend on cooking time, but only on temperature.
Here is, for example, a 65°C egg:
I - 6 (of 17)
Figure 6. An egg cooked at 65°C for more than two hours. As fas as thermal equilibrium is
reached, the final state does not depend on time, but only on temperature. At 65°C, the egg
white is slightly coagulated, but the yolk is still liquid. This new egg has nothing to hard boiled
eggs, fried eggs, poached eggs, etc. It’s an “egg at 65”.
From eggs to meat and fish
After egg white, which is the simplest case, let’s move to fish and meat. In both cases, some proteins
and water molecules are inside “muscular fibres”, i.e. long “tubes” whose “skin” is made of a special
tissue called collagenic tissue. This tissue is indeed not woven, but made of adjacent microfibers of a
special kind of proteins, called collagen. In meat and fish, the collagen molecules wrap around one
another by three, forming “triple helices”. And the collagenic tissue is gluing the fibres in bundles.
Some bundles are even groups in super bundles, and so on. The more collagen content, the harder