As a coating material, gelatin has many advantages on food surface: ① avoiding food oxidation and inhibiting Maillard reaction between amino acids and sugar; (2) preventing powdery and granular sugar foods from absorbing moisture and caking; ③ Make the surface of food shiny; (4) As a stabilizer, it can prevent the product from shrinking and deforming; ⑤ It has the function of keeping fresh. Adding a certain amount of gelatin solution to the sugar solution soaked in fruits and vegetables can form a protective film on the surface of fruits and vegetables to ensure the natural flavor and freshness of food. ⑥ Prevent food from spoilage. Extend the shelf life of food; ⑦ Improve the preservation of volatile food ingredients; ⑧ Adjust solubility, and so on.