ã€Chinese Packaging Network News】: Aseptic packaging technology was born in the late 40s of last century, starting from the 60s of last century, with the development of plastic packaging materials for the application of aseptic packaging technology provides a vast world. Due to the process features of aseptic packaging and the advantages of less destructiveness to food nutrients and flavors, coupled with lower cost, convenient storage and transportation, and beautiful appearance, it has been welcomed by businesses and consumers. In recent years, with the advancement of science and technology, the development of aseptic packaging technology equipment and materials is even more powerful. The packaging market is constantly expanding. Aseptic packaging in developed countries accounts for more than 65% of the proportion of liquid food packaging. The market prospect is extremely broad.
What is aseptic food packaging
The so-called aseptic food packaging is about to sterilize foods (beverages, dairy products, seasonings, etc.) packaged in a sterile environment, sealed in a sterilized container in order to obtain longer without preservatives and without refrigeration Shelf life. Simply put, aseptic packaging is to first sterilize packaging materials, packaging containers and contents, and then packaging in an aseptic environment rather than aseptic packaging. The packaging container and contents are then sterilized together. The meaning of aseptic in the food industry means that the number of non-pathogenic bacteria per gram of food is less than 10. As long as the non-pathogenic bacteria in the food are no longer propagated, the possibility of food deterioration will not occur if the food is circulated or stored at room temperature under refrigerated or frozen conditions.
Packaging material sterilization method
Aseptic packaging includes the sterilization and sterilization of packaging materials, sterilizing treatment, sterilization of packaging contents of food, and sterilization of packaging environment. At present, the commonly used sterilization methods for packaging materials include drug sterilization and UV sterilization.
1, drug sterilization. In the sterilization of drugs, the bactericide used must be a drug that has strong sterilizing ability, no corrosion to the equipment, no harmful substances in the sterilizing process, and less residue in the packaging material.
At present, the most commonly used bactericide is hydrogen peroxide, which is generally referred to as hydrogen peroxide. The bactericidal capacity of hydrogen peroxide is related to its concentration and temperature. The higher the concentration, the higher the temperature the better its ability to kill bacteria. The concentration of hydrogen peroxide used for sterilization is 25% to 30% and the temperature is 60-65°C. Sterilization with hydrogen peroxide should be combined with heat treatment because hydrogen peroxide will have better bactericidal efficacy when it is heated to evaporate from the surface of the material.
The sterilization of the packaging container with hydrogen peroxide is carried out by immersing the packaging container in hydrogen peroxide or directly spraying hydrogen peroxide on the packaging container. They are then heat-radiated so that the hydrogen peroxide remaining on the packaging container is completely evaporated together with the hot air and decomposed into harmless water vapor and oxygen.
2, ultraviolet sterilization. In general, the effect of UV sterilization is most intense when it is related to the wavelength of UV light, the degree of illumination, and the time of exposure to light, which is around 250-360 nm.
The principle of UV disinfection is mainly due to the fact that nucleic acids in the cells of microorganisms after UV irradiation produce chemical reactions that cause the metabolism of microorganisms to lose their ability to proliferate. Ultraviolet sterilization is one of the more effective methods for aseptic packaging or clean packaging. It has the advantages of high safety, non-residual use, and low cost. However, compared with hydrogen peroxide, its bactericidal effect is not very good. It should be used in combination with other methods of sterilization.
Commonly used aseptic packaging
Currently used aseptic packaging forms are aseptic cardboard packaging, sterile cup packaging, aseptic bag packaging, aseptic aluminum/plastic bag packaging and aseptic plastic bottle packaging.
1, sterile cardboard packaging. The aseptic paperboard packaging material is a cardboard/aluminum/plastic composite material. Among them, cardboard is a structural material. Its pulp distribution ratio and performance are proprietary technologies, and its aluminum foil is a barrier material for its unique packaging machine. The general thickness is 9um and the packaging must be free from porosity and damage; polyethylene is in contact with food. The inner material is a heat seal material.
Aseptic cardboard packaging capacity is generally 200-1000ml. The packaging is in the form of brick and roof packages. Mainly used for dairy products. Juice, beverages, etc. packaging
2, sterile cup packaging. The cup material used in the aseptic cup packaging is a multi-layer co-extruded neutral sterile packaging sheet (Neutrela septic system) abbreviation NAS sheet.
The sheet is characterized by a peelable outer layer. When co-extruded, the chemical incompatibility of PP and PE is utilized, and the PP, PE materials matching the flow stability form a smooth and aseptic process during the co-extrusion process. At the interface between the company and the company, the NAS sheet on the aseptic packaging machine was opened to remove the PP protective film before entering the sterile area, exposing the PF sterile surface and completing the entire process of forming, filling, and capping in the sterile field.
Another feature of the sheet is a high barrier material PVDC or EVOH. Because PVDC and EVOH have excellent barrier properties against oxygen, the shelf life of foods packaged with NAS sheets can be comparable to that of glass bottles. Tin cans are comparable to each other.
In the material structure of the aseptic cup packaging, the aluminum foil is the middle layer of the barrier material with the MPE, LDPE and VA containing 7% of EVA3 layer coextruded film. This is because MDPE has good rigidity and good thermal adhesiveness with aluminum foil; while IDPE in the middle is cheaper: the contact layer with food is EVA with VA content of 7%. Because the content of EVA is generally above 14%, it is not allowed to directly contact foods with EVA instead of IDPE as the heat seal layer. The heat sealing temperature can be reduced, the anti-fouling ability of the heat seal layer can be improved, the heat seal dwell time can be shortened, and the line speed of the production line can be increased.
3, aseptic bag packaging. Aseptic bag packaging refers to a composite bag with a packaging capacity of 5-220L up to 1000L. The filled bag is packed in an outer box made of wood or cardboard or in a steel drum. The main packaged thick stock or base material 5-20L can also be used directly for household consumption. This kind of packaging form has basically replaced the iron. Buckets or plastic buckets for packaging. Then add preservatives to foods to preserve food packaging methods.
There are two forms of material structure for large bag packaging - PET film/aluminum foil/PE film or PET aluminized film/PE film is compounded by a dry composite method. Because the aluminum-plated membrane is easy to have porosity, it can not guarantee its barrier performance. Therefore, aluminum foil is generally used as a barrier material in China.
4, sterile aluminum / plastic packaging and bottle packaging. Sterile aluminum/plastic packaging is similar to sterile paper packaging. Only the material used is aluminum/plastic composite film. The packaging is in bags. The packaging film used is mostly dry composite and cast composite.
Sterile bottle packaging uses co-extruded plastic bottles or single-component PP and PE. Plastic bottles can be sterilized at the time of molding and immediately filled or sterilized before filling can be filled and capped in a sterile room.
5, liquid food aseptic packaging composite paper. The use of aseptic packaging for liquid foods has become a more popular international trend. In particular, aluminum foil composite paper packaging is the more common reason is that this type of packaging can make the packaged material in the ideal environment of opaque, airtight, sterile, can also be maintained at room temperature for more than 12 months and the quality of the same At the same time, its light weight can be shipped long distances. The technical points include: (1) Before the color printing or compounding, special surface treatment is performed on the base paper to increase the firmness of the anvil bond. (2) On the premise of ensuring firm drilling, the surface of the composite PE layer and the aluminum foil and the base paper The thinner the PE layer, the better to reduce the cost and prevent the use of excessive PE causing operational problems. (3) The thickness of the innermost layer of the product, ie the food contact layer, should not be less than 0.907 mm; (4) The PE layer should strive to control the thickness uniformity. Avoid waves and blisters.
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