Gelatin is made of the degradation of the collagen part in skin, bone, sarcolemma, muscle and other connective tissue of animals. It is a white or light yellow, translucent, micros trip shiny sheet or powder. Therefore, it is also called animal gelatin or fat glue. Industrial gelatin is colorless or pale yellow transparent or translucent sheet or powder. It is tasteless and odorless. Moreover, gelatin can swell in cold water and dissolved in hot water. It is soluble in glycerol and acetic acid, while insoluble in ethanol and ether.
Water and inorganic salts in gelatin account for about 16%, and protein content accounts for more than 82% in Gelatin. Similar to maternal collagen, gelatin is also made of 18 kinds of amino acids, in which, the content of Pro and hyp in amino acids is higher. The three-helix structure in gelatin gel is mainly composed of hydrogen bonds and hydrogen bond hydride. Pro--NH, Hyp-OH and other amino acid side chain groups and water molecules can form hydrogen bonds, and structural stability.
Gelatin can be divided into skin gelatin and bone gelatin according to the raw materials. Skin gelatin can be subdivided into bovine skin gelatin, pig skin gelatin, chicken gelatin, fish gelatin and so on. What’s more, bone gelatin can be subdivided into bovine bone gelatin, pig bone gelatin, chicken bone gelatin and fish bone gelatin. Scale gelatin is a kind of gelatin extracted from fish scales in recent years. Gelatin is a macromolecular hydrophilic colloid. It is a kind of low calorie health food with high nutritional value. It can be used as confectionery additives, frozen food additives and so on.
Based on the difference of raw materials, production methods, product quality and usage, gelatin can be divided into edible gelatin, medicinal gelatin, industrial gelatin, photographic gelatin, leather gelatin and bone gelatin. In industrial usage, it is customary to use the protein for the extraction of hydrolyzed animal protein called animal gelatin, in feed additives called feed gelatin, and in match industry called match gelatin. Moreover, for the packaging and other products of hot gel gelatin, it is called hot melt adhesive powder.