to coagulate. However, gnocchi, pasta and other wheat-flour based products only keep their shape
thanks to a coagulated protein network.
Thus understanding coagulation, coagulation temperatures of the different proteins, and factors that
affect coagulation, can be very useful in the kitchen.
Factors favouring coagulation:
An unwound protein will contain areas along its chain that are charged, and these tend to prevent
coagulation. This is because areas that are similarly charged (for example negatively charged areas
on two neighbouring denatured protein strands) will tend to repel each other, reducing the chance of
subsequent inter-chain bonding and thus network formation. This repulsion can be prevented by
adding molecules to the protein mixture that are small and charged (such as the H+ in acid and Na+
and Cl- ions in salt). These molecules will be attracted to protein regions of opposite charge to
themselves, and help them “locate”, and eventually bond to, areas on other protein strands from which
previously they would be repelled.
The H+ ions also have an additional property that favours coagulation – as mentioned above, the
presence of acid increases the rate at which proteins denature, which will further increase the rate of
H+ H+ H+
Factors disfavouring coagulation:
This can be achieved by adding substances that reduce the movement of the denatured proteins,
making their subsequent coagulation difficult.
In cooking, these molecules tend to be long uncharged molecules (like, for example, starch
IV/II - 5 (of 6)
As more and more bonds are formed between different unwound chains (including the electrostatic
forces between positive and negative parts; the hydrophobic interactions between different
hydrophobic parts; and the sulphur bridges between sulphur atoms), the network will become stronger
and tighter, until eventually it will start to push out the water. This is called synergesis.
The process of syneresis is always undesired in cooking, since it is unattractive and results in foods