In gelatins, the hydrophilic (water-attracting) and hydrophobic (water-repelling) molecules and their interfaces have an influence over the interface of gelatin. These properties will decide the amphoteric and amphiphilic behavior. It will characterize the foaming ability, the stability of emulsions, it's adhesiveness and solubility in solutions.
Gelatin, a protein, depending upon the amino acid content in it has different distribution of charge in it. Amino acids are charged depending upon the side chains on it's structure. The charge on the protein is pH-dependent.
Isoelectric point is defined by the state wherein the electric positive charges are equivalent to electric negative charges within the molecule. The overall effect is neutral. The isoelectric point is approximately pH 9 in native collagen. Gelatin is produced by partial hydrolysis of collagen. There are two types of gelatin:
Type-A (acid processed): Isoelectric point is between 8 and 9.
Type-B (alkaline processed): Isoelectric point is between 4.8 and 5.4
In the application of gelatin, IEP plays a major role in determining the turbidity and it's precipitation.
Gelatin comprises of different lengths of protein chains. These protein chains consist of long hydrophobic chain segments and short hydrophilic segments. These structures are characterized for showing surface activities. Gelatin is capable of decreasing the surface tension and attaches to the film due to its adhesive nature. Technologically, we at Abalone use this ability in the formation and stabilization of multi-phase systems.