ABSTRACT
Protein gelation might first have been experienced by a slack Bronze Age cook who put off doing the dishes and found the gravy congealed in the pot next morning. Gels, such as those from milk and egg, must have been part of human food for a very long time, and until recently they must have seemed very mysterious. The chemical structure of proteins allows a range of properties unequalled by other polymers. It is therefore not surprising that in biology—especially in animals—natural gels often consist of protein or protein attached to carbohydrate. Food proteins, which are rarely pure and are often used with other ingredients, are even more difficult to deal with quantitatively, so in general their physical properties must be treated empirically. The stability of protein structures arises from a combination of covalent bonds, particularly disulfide bones, with noncovalent, intermolecular connections provided by hydrogen and electrostatic bonds and hydrophobic effects.
