Gelatin is a high molecular polypeptide polymer obtained by partial hydrolysis of collagen contained in animal skin and bone.

The appearance of gelatin is nearly white or light yellow, almost odorless, tasteless, transparent or translucent solid flakes or powder particles. The molecular weight of gelatin is 10000-70000, and the molecular weight of superior gelatin is between 100000 and 150000. The amino acid composition of gelatin is very special, sulfur-containing amino acid is very low, and the content of glycine, alanine, proline and hydroxyproline is very high, accounting for 67% of the total amino acid content, which is about three times of the content of the four amino acids in other mammalian proteins.

Gelatin is insoluble in cold water, but it absorbs 5~10 times the weight of cold water, expands and softens, dissolves in hot water, and forms gel after cooling. The difference between dissolution temperature and coagulation temperature is very small. It is dissolved at about 30 degrees centigrade and solidified at 20~25 degrees centigrade.

Gelatin is easy to absorb moisture and deteriorate in air, so it should be stored in a sealed and dry way. Avoid direct sunlight, high temperature and caking.