Applying a film on the surface of some foods not only looks bright and beautiful, but also regulates breathing and prolongs the shelf life. These substances used for the appearance of foods, which are used for preservation, preservation, glazing, prevention of mold erosion and evaporation of water, are called filming agents. The surface of the fruit is coated with a film to inhibit the evaporation of water, prevent the intrusion of microorganisms, and form a gas-conditioning layer, thus prolonging the preservation time of the fruit. Some candy, such as chocolate, is not only bright and beautiful after being coated on the surface, but also prevents adhesion and maintains stable quality. Recently, some preservatives, antioxidants, and the like have been added to the film to further prepare a composite preservative. Commonly used coating agents are natural beeswax, paraffin, shellac, etc., in addition to some synthetic products, such as morpholine fatty acid salts. The filming agent can be roughly classified into two types, a spray type and a cover type. Spray coating agents include shellac products, paraffin wax, beeswax, sodium oleate, shellac formulations, ethylene oxide, higher fatty alcohols, morpholine fatty acid salts, magnesium silicates, vinyl acetate resins, and the like. The coating type coating agent is a glutinous rice coating, a paraffin impregnated paper, a polyvinyl acetate or the like. China's GB2760-1996 regulations allow for the use of nine kinds of coating agents on food: shellac, paraffin, liquid paraffin (white oil), morpholine fatty acid salt (fruit wax), rosin pentaerythritol ester, octyl phenoxy Poly(ethyleneoxy), dimethylpolysiloxane, carnauba wax, stearic acid.
    
    
    
        
    
    
    
        
            
                
                
                    
                        
                        
                        
                        
                        
                        
                            
                                
                                - 
                                    Amino compound
                                    
                                     >
                                
- 
                                    
                                    Oxy-containing amino compound
                                    
                                    
                                    Cycloalkylamines, aromatic monoamines, aromatic polyamines and derivatives and salts thereof
                                    
                                    
                                    Acyclic monoamines, polyamines and their derivatives and salts
                                    
                                    
                                    Amide compound
                                    
                                    
                                    Sulfonic acid amino compound
                                    
                                    
                                
- 
                                    Alcohols, phenols, phenolic compounds and derivatives
                                    
                                     >
                                
- 
                                    
                                    2-cycloalcohol
                                    
                                    
                                    Halogenated, sulfonated, nitrated or nitrosated derivatives of alcohols
                                    
                                    
                                    Extremely halogenated, sulfonated, nitrated or nitrosated derivatives of phenols
                                    
                                    
                                    Phenol and its halogenated, sulfonated, nitrated or nitrosated derivatives
                                    
                                    
                                    Acyclic alcohol
                                    
                                    
                                
- 
                                    Nitrogen-containing compound
                                    
                                    
                                
- 
                                    
                                
- 
                                    Nitrile compound
                                    
                                    
                                
- 
                                    
                                
- 
                                    Organic derivative of hydrazine or hydrazine
                                    
                                    
                                
- 
                                    
                                
- 
                                    Terpenoid
                                    
                                    
                                
- 
                                    
                                
- 
                                    Ether compounds and their derivatives
                                    
                                     >
                                
- 
                                    
                                    Ether, ether alcohol
                                    
                                    
                                    Halogenation, sulfonation, nitration or nitrosation of ethers, ether alcohols, ether phenols
                                    
                                    
                                
- 
                                    Aldehyde
                                    
                                    
                                
- 
                                    
                                
- 
                                    Carboxylic compounds and derivatives
                                    
                                     >
                                
- 
                                    
                                    Cyclic carboxylic acid
                                    
                                    
                                    Halogenation, sulfonation, nitration or nitrosation of carboxylic acids
                                    
                                    
                                    Halogenation, sulfonation, nitration or nitration of carboxylic anhydrides
                                    
                                    
                                    Carboxylic acid halide
                                    
                                    
                                    Carboxylic esters and their derivatives
                                    
                                    
                                    Salt of carboxylic acid ester and its derivatives
                                    
                                    
                                    Acyclic carboxylic acid
                                    
                                    
                                
- 
                                    Hydrocarbon compounds and their derivatives
                                    
                                     >
                                
- 
                                    
                                    Aromatic hydrocarbon
                                    
                                    
                                    Cyclic hydrocarbon
                                    
                                    
                                    Hydrocarbon sulfonate
                                    
                                    
                                    Hydrocarbon halide
                                    
                                    
                                    Hydrocarbon nitrite
                                    
                                    
                                    Acyclic hydrocarbon
                                    
                                    
                                
- 
                                    Ketone compound
                                    
                                    
                                
- 
                                    
                                
- 
                                    Alkyl ureas and their derivatives and salts
                                    
                                    
                                
- 
                                    
                                
- 
                                    Inorganic acid ester
                                    
                                    
                                
- 
                                    
                                
- 
                                    Heterocyclic compound
                                    
                                    
                                
- 
                                    
                                
- 
                                    Diazo, azo or azo compound
                                    
                                    
                                
- 
                                    
                                
- 
                                    Organosilicon compound
                                    
                                    
                                
- 
                                    
                                
- 
                                    Organometallic compound
                                    
                                     >
                                
- 
                                    
                                    Organic palladium
                                    
                                    
                                    Organic germanium, cobalt, strontium, barium, gallium, germanium, germanium, germanium, germanium, etc.
                                    
                                    
                                    Organic calcium
                                    
                                    
                                    Zirconium
                                    
                                    
                                    Organic potassium
                                    
                                    
                                    Organic
                                    
                                    
                                    Organic lithium
                                    
                                    
                                    Organic
                                    
                                    
                                    Organic aluminum
                                    
                                    
                                    Organotin
                                    
                                    
                                    Organic manganese
                                    
                                    
                                    Organic sodium
                                    
                                    
                                    Organic nickel
                                    
                                    
                                    Organic titanium
                                    
                                    
                                    Organic iron
                                    
                                    
                                    Organic copper
                                    
                                    
                                    Organotin
                                    
                                    
                                    Organic zinc
                                    
                                    
                                    Organic
                                    
                                    
                                    Organic
                                    
                                    
                                    Organic germanium, mercury, silver, platinum, etc.
                                    
                                    
                                    Organic germanium, antimony, bismuth, tungsten, antimony, bismuth, lead, vanadium, molybdenum, chromium, antimony, etc.
                                    
                                    
                                
- 
                                    Organic sulfur compound
                                    
                                    
                                
- 
                                    
                                
- 
                                    Organic phosphine compound
                                    
                                    
                                
- 
                                    
                                
- 
                                    Organometallic salt
                                    
                                    
                                
- 
                                    
                                
- 
                                    Organic fluorine compound
                                    
                                     >
                                
- 
                                    
                                    Fluorobenzoic acid series
                                    
                                    
                                    Fluorobenzonitrile series
                                    
                                    
                                    Fluorobenzaldehyde series
                                    
                                    
                                    Fluorobenzyl alcohol series
                                    
                                    
                                    Fluoroanisole series
                                    
                                    
                                    Fluoroaniline series
                                    
                                    
                                    Fluorophenylacetic acid series
                                    
                                    
                                    Fluorophenol series
                                    
                                    
                                    Fluorobenzoic acid series
                                    
                                    
                                    Fluoronitrobenzene series
                                    
                                    
                                    Fluoropyridine series
                                    
                                    
                                    Potassium fluoroborate series
                                    
                                    
                                    Fluorobenzyl alcohol series
                                    
                                    
                                    Fluorotoluene series
                                    
                                    
                                    Fluorine red series
                                    
                                    
                                    Fluoroethane series
                                    
                                    
                                    Fluoropropane series