application fields of irradiation
Writer: Sterilization Time: 2020-09-02 Browse: 680 ℃
Application fields of irradiation technology
At present, the fields of industrialization and commercialization are: food irradiation preservation, radiation sterilization and disinfection of medical supplies, radiation chemical industry, three wastes treatment, etc.
Development opportunities of radiation processing industry
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Food irradiation 45%
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Flue gas treatment 7%
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Drugs 4%
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Sterilization of health care products: 21%
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Polymer modified 6%
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Profiling parts 2%
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Sterilization of packaging materials: 11%
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Natural phytochemical functional food 5%
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Cables 2%
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Cosmetics 2%
1. Field of food irradiation preservation
At present, there are many disinfection and sterilization methods, such as thermal disinfection, chemical agents (including liquid and gas disinfectants), ultraviolet disinfection, microwave disinfection, ultrasonic disinfection, ionizing radiation sterilization, etc
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① High temperature and high pressure (pressure steam sterilization) method;
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② Gas fumigation (ethylene oxide) method;
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③ Sterilization by ionizing radiation (gamma ray and electron beam).
The high temperature and high pressure method is the earliest sterilization method: its main disadvantages are: the sterilization is not complete; it is not suitable for those heat sensitive materials (such as plastic products, some rubber products, etc.); this method also consumes a lot of energy; it can not operate continuously and cannot be produced in large quantities. This is a primitive and backward method.
Gas fumigation method
Gas fumigation method: the gas of chemical substances is used to fumigate the sterilized articles. The main chemical substances used are ethylene oxide, methyl bromide, etc. Compared with the former method, it has made great progress: it can be produced in large quantities and sterilized thoroughly. However, there are many disadvantages of this method: many process parameters and difficult control; continuous production; the packaging materials must be breathable (and not permeable); there will be microbial residues in the sterilized products where there is compression and can not seep into the gas; there are chemical residues in the products. It is particularly worth pointing out that these chemicals are strong carcinogens. Although there are clear limits on the residues, they still exist and pose a threat to human health.
After the first two methods, advanced radiation sterilization methods have been adopted. The main radiation sources used are γ - ray produced by radioisotope cobalt-60 and high-energy electron beam or X-ray produced by accelerator. This method is a kind of environmental protection sterilization method: its sterilization process is easy to control (only need to control the radiation dose); the sterilization is complete, and there is no problem of heat convection and gas diffusion; because it is carried out at normal temperature, the method is applicable to all kinds of heat sensitive materials and products; it can be produced continuously in large scale; the product will not produce induced radioactivity and has no pollution.
Irradiation sterilization method
Irradiation sterilization method: it is the most advanced sterilization method at present. Most medical and health products in advanced countries are sterilized by this method. It is a consensus that irradiation sterilization should replace other sterilization methods. It is an irreversible trend that ethylene oxide gas fumigation is eliminated.
In fact, irradiated food is gradually entering the homes of ordinary people, such as dehydrated vegetables, instant noodle seasoning and vacuum packaged cooked meat products, health drinks, native products, etc.
Irradiated food uses 60Co gamma ray, X-ray or high-energy electron beam to pass through the food body. After ionizing the water and various nutrients, the DNA molecules in the cells are destroyed (cytoplasmic damage and biofilm damage are also important processes), so as to inhibit the germination and rooting of vegetables. After irradiation, the stored time of garlic, potato and onion can be prolonged by 6-12 months.
After irradiation, the spoilage and pathogenic microorganisms such as mould and Escherichia coli can be completely eliminated, thus greatly extending their shelf life.
2. Radiation sterilization of medical products
Application of irradiation disinfection of medical products: irradiation disinfection has the advantages of complete sterilization, no pollution, no residue, low price, energy saving, convenient operation, and can be sterilized at room temperature. It has developed into an irreplaceable new technology and formed a certain industrial scale, especially after almost all chemical disinfection and sterilization methods were abolished in the world. Its application has irreplaceable significance.
3. Industrial field radiation chemical industry
Radiation chemical products are the fastest developing field of radiation processing technology. Radiation chemical engineering is a new processing method to modify materials by chemical changes (chemical combination, decomposition, crosslinking, polymerization, grafting, curing, degradation, etc.) produced by ionizing radiation. Compared with the conventional processing technology (thermal processing, optical processing, chemical processing, etc.), it has the following main characteristics: it can react at room temperature to low temperature without adding initiator or catalyst, and can synthesize or prepare high-performance special materials which are difficult to obtain by conventional methods.
Radiation chemical products have high added value and wide application, involving communication electronics, electric power transportation, petrochemical, aerospace and many other important areas of national economy, and occupy a very important position in the same radiation technology industry. In recent ten years, with the upgrading of industrial structure and the enhancement of environmental protection awareness in the world, radiation chemical industry, as an efficient, energy-saving, pollution-free and easy to control green chemical industry, has attracted worldwide attention and shown great vitality. Because of its simple process, easy operation, good product quality and good benefit, it is rapidly industrialized at a very high speed. Radiation chemical industry is mainly to produce chemical products by polymerization of multiphase polymer initiated by γ - ray irradiation. In this field, many products have been produced on a large scale. For example, heat shrinkable materials have been applied to electric power and various sectors.
4. Other applications
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① In agriculture, the method of radiation induced artificial mutation is called mutation breeding, that is to use mutation to improve varieties. In other words, the useful shape and quality can be directly used as variety or as female parent material for mating. The aim is to increase yield and use early maturing varieties. Gratifying results have been achieved in these areas.
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② Sterilization of compound feed for animals: more than 30 varieties of feed additives were designated for radiation treatment long ago. The application of radiation processing technology in the treatment of aseptic feed has got considerable development, and its application prospect is very considerable. It is proved that high dose irradiation of protein and amino acids almost does not cause changes in nutriology. Besides vitamins A and E, there are no problems in the radiolysis of vitamins. The decomposing degree of vitamin A and vitamin E is similar to that of heating treatment, especially the vast majority of experimental feed is treated by radiation processing. Leading enterprises in China's feed industry, such as Hunan Quyuan Zhenghong science and technology group and Zhengda Group, can consider introducing this technology and project in the field of feed production and meat products preservation.
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③ Radiation processing starch: radiation treated starch has been widely valued and used as a by-product of aquatic products, infant food, patient food, and filling agent of dried meat juice. In a word, the purpose of radiation treatment of starch is to improve the quality of industrial raw materials, sterilization and processing adaptability of food materials.
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④ Radiation processing of immobilized enzyme: enzyme is a kind of protein which can catalyze biological objects. Because it is soluble in water, it can only be used once. After reaction, there is residual activity of enzyme, but it is not recyclable for enzyme. After heating, coagulation and precipitation, it can only be taken out and thrown away. The use of enzymes like this is uneconomical in terms of resource savings. If the enzyme can be solidified and participate in the comprehensive reaction, the automation and continuity of enzyme reaction can be carried out. This complex is produced under 60Co γ - ray irradiation. For example, in 1975, Kawasaki, Japan, froze the mixture of acrylamide and enzyme on dry ice acetone. Under the premise of no nitrogen replacement, the seeds were irradiated with 60Co gamma ray at a dose of 1-9gy per hour for 5-10 minutes to combine them. After thawing, the immobilized enzyme with sponge structure or Rosary shape could be produced.
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⑤ Disinfection, sterilization and antisepsis of leather: it has a special effect on fresh and newly stripped leather. For example, the cowhide just peeled off. The sheepskin can be treated by radiation processing, which can keep it from spoilage and taste, and keep it from rotting for a long time.
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⑥ Forage: there are many microorganisms and bacteria in the forage for cattle and sheep. In order to ensure the healthy reproduction of cattle and sheep, the grass processed by radiation has been fed. In particular, these grasses are processed by radiation when they are exported.
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⑦ It is also widely used in other fields, such as commodity maintenance, flower preservation and so on.
It can be seen from the above that irradiation technology is widely used. It has been proved that radiation processing technology is a high and new technology which is moving towards industrialization and commercialization, and it also shows that radiation processing technology is a cause full of vitality.
