As we all know, the current food packaging is a large package industry, accounting for about 70% of the packaging industry. Therefore, the food packaging waste is also the largest environmental pollution. In order to better store food and avoid environmental pollution caused by packaging waste, the green packaging application of food is imperative. Green packaging material Broadly speaking, green packaging materials are packaging materials that are harmless to human health, have good protection for the ecological environment, and are recyclable during production, manufacture, use, and recycling. 1. Reuse and recycled packaging materials Repeated use of packaging, such as beer, drinks, soy sauce, vinegar and other glass bottles can be used repeatedly. Sweden and other countries implement repeated reuse of polyester beverage bottles and PC milk bottles for more than 20 times. Recycling packaging, such as polyester bottles, can be recycled after physical and chemical methods. The physical method refers to direct and thorough purification and smashing without any residual contaminants. The treated plastics are then directly used to produce recycled packaging containers. The chemical method means that the recovered PET bottle is crushed and washed, and then the depolymerization agent such as methanol water, ethylene glycol, or diethylene glycol is used to depolymerize all the PET into monomers or partially depolymerize into oligomers under the action of a basic catalyst. The monomers or oligomers are then re-polymerized into recycled PET resin packaging material. The repeated use and regeneration of packaging materials only prolongs the service life of plastics and other polymer materials as packaging materials. After reaching the end of its service life, it still faces the problems of waste disposal and environmental pollution. 2. Edible packaging materials The development of edible packaging materials is the best way to solve the contradiction between food packaging waste and environmental protection. The goal pursued in the development of edible packaging is to produce a packaging film that does not affect the flavor of the packaged food, which can be consumed. For example, glutinous rice paper used for candy packaging and corn baking packaging cups for packaging ice cream are well known. The pullulan resin that has been put into industrial production in the 1970s is an odorless, amorphous, amorphous white powder, and is a non-ionic, non-reducing, stable polysaccharide. Because it is easily dissolved in water, it can be used as a viscous, neutral, and non-liquoring non-gelling aqueous solution. Its 5%～10% aqueous solution can be made into a film with a thickness of 0.01mm by drying or hot pressing. This film is transparent, colorless, odorless, non-toxic, has toughness, high oil resistance, can be eaten, and can be used as food. package. Its gloss, strength, and folding resistance are better than films made from high-chain starch. There is also an edible cling film, which has been developed into a multi-component edible film made of a variety of biological macromolecules (proteins and polysaccharides) and lipids having various functional properties. Such composite membranes mainly form a stable emulsion by interacting with different molecules, and then they are dried to volatilize the solvent to form a porous, transparent or translucent film of a three-dimensional network structure. The porous network structure enables the membrane to have The obvious waterproofness and certain selectable breathability, therefore, has a broad application prospect in the food industry, especially in the preservation of fresh fruits and vegetables. 3. Degradable packaging materials Degradable packaging material refers to a plastic whose chemical structure changes at a specific time and in a specific environment. Degradable plastics not only have the functions and characteristics of traditional plastics, but also can be split and degraded in the natural environment through the action of ultraviolet light in the sunlight or the action of microorganisms in the soil and water after the service life is completed, and finally renewed in a non-toxic form. Enter the ecological environment and return to nature. Biodegradable plastics are generally classified into synthetic photodegradable plastics, photodegradable plastics and biodegradable plastics added with photosensitizers, and multi-functional degradable plastics combined with various degradable plastics. According to the degradation environmental conditions, degradable plastics can be divided into photodegradable plastics, biodegradable plastics (fully biodegradable plastics and partially biodegradable plastics), chemically degradable plastics (oxidative degradable plastics and water degradable plastics), and the above three kinds of degradation. Plastic composite degradable plastic. Among synthetic photodegradable plastics, polyhydroxybutyrate (PHB) and polyhydroxyvalerate (PHV) are the most widely produced. Their properties are similar to that of polyethylene and polypropylene, and the price is about 10 times that of polyethylene. The principle of its degradation is that the polymer absorbs ultraviolet light to initiate the photoinitiation, so that the bond energy is weakened, long chains are split into lower molecular weight fragments, and physical properties are degraded. The lower molecular weight fragments are further oxidized in the air, generating radical chain scission and further degrading to carbon dioxide and water. In the plastic processing process, adding a small amount of photosensitizer can make general plastics become photodegradable plastics. This method is simpler than the copolymerization synthesis method and the cost is lower. Photodegradable plastics are mainly used as beverage bottles, shopping bags, garbage bags, and plastic films in foreign countries. Domestic research and development of photodegradable plastics are mainly used for plastic film. In recent years, photodegradable plastics have been developed for use in disposable snack boxes. Because photodegradable plastics can only be degraded under solar irradiation conditions, they are greatly constrained by geographical environment and climatic conditions. To achieve accurate time control, it is difficult to degrade and the buried part cannot be degraded. Therefore, large-scale application is subject to certain restrictions. limit. Polymers based on petroleum as raw materials are difficult to be decomposed by ordinary microorganisms under natural conditions. Polymers and natural polymers synthesized from genes that are prone to hydrolysis have high biodegradability. Researches in our country are based on the incomplete biodegradable plastics that are blended with starch and polyolefin plastics. The degradation principle of such plastics is that starch granules are first eroded by fungi and bacteria and consumed, thereby weakening the strength of the plastics. At the same time, the starch granules are subjected to autoxidation and contact with some salts existing in the soil to form peroxides, which promote the polymer in the plastics. The molecular chain breaks, they promote each other, complement each other, the bacteria consumes the starch, causes the plastic surface area to increase to be advantageous to the auto-oxidation degradation. As time goes by, the polymer chain gradually breaks and shortens, so that the plastic strength decreases until the molecular weight of the polymer is reduced to the extent that it can be metabolized by microorganisms. 4. Paper packaging materials The raw materials of paper are mainly natural plant fibers, which will quickly rot in nature, will not pollute the environment, and can also be recycled for papermaking. Pulp molded products not only have the advantages of light weight, low cost, shock resistance, etc., but also have the characteristics of good air permeability, which are conducive to the preservation of fresh foods. 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