Gelatin is the homologous protein of collagen and partially hydrolyzed by it. The amino acid composition of gelatin is close to that of collagen. Gelatin molecules can form positive ions, anions, or zwitterions in solutions with different pH values. Collagen has a rod-shaped triple-helix structure, which is partially separated and broken when it is hydrolyzed. According to the different preparation methods, gelatin can be divided into two types. Type A, derived from hog skin and hydrolyzed by acid, has good plasticity and elasticity. Type B is mainly hydrolyzed by alkali from bones and animal skins and has a good hardness performance. The intensive use of gelatin in food is in gel desserts because of the unique feature of “melting at mouth temperature.” It has also been used in photographic emulsions to protect colloid (Figure).
Thickening and stabilizing are the main applications in the food of gelatin as well as electrospun gelatin nanofibers, of which the amounts are smaller and the effects are stronger. The concentration of type B gelatin powder from bovine skin and the applied voltage have been investigated in research by Okutan et al. It is demonstrated that electrospun gelatin nanofibers are nanoscale only at the concentration of 20% (w/v) gelatin. Furthermore, the lower the applied voltage is, the higher the z potential and diffusion coefficient values for electrospun gelatin nanofiber dispersions are. According to a study, gelatin from cold-water fish skin is electrospun and then crosslinked. Water or concentrated acetic acid served as electrospinning solvents and both of them are electrospun successfully. There are three different techniques, namely GTA vapor, genipin, and dehydrothermal treatment, applied in the crosslinking process. The results of three studies show that fish gelatin modified with GTA is the most suitable substrate.