Gelatine is formed by the denaturation or solubilisation of the parent protein collagen found in
skin and bones. With pigskin, because the animals are relatively young, the skin is simply
acidified to the desired extraction pH and then heated to denature and solubilise the collagen.
With bovine hide, due partly to the greater age of
the animal at slaughter, it is necessary to
subject the hide to depilation with sodium sulphide
and alkaline hydrolysis of the stabilised
cross-links by steeping in a lime suspension for a
period of 1 to 6 weeks.