Development direction of sterilization technology

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The development direction of food packaging sterilization technology

in recent years, the sterilization technology of packaged food, which is energy-saving, safe, reliable, effective and low-cost, has been developed and applied one after another, greatly promoting the production and development of packaged food

irradiation sterilization technology: it uses the radiation produced by the radioactive isotopes cobalt 60 and cesium 157 or the p-ray emitted by the low-energy accelerator to irradiate the packaged food. The radioactive substance cobalt 60 is widely used in Canada, Israel, France, Japan and other countries. The powerful 7-ray emitted by it can completely destroy the genetic factors of bacteria and their physiological activities. Almost any bacteria can be destroyed when using the high truss aerial work platform jg/t5104 ⑴ 998 dose

complete sterilization by irradiation: irradiating the sealed food at 2500-5000 kilorads can kill all pathogenic microorganisms that damage the food, so as to achieve the purpose of commodity disinfection. Before irradiation, salt and sodium triphosphate can be added to food, which can reduce the water loss of food and enhance the killing ability of radiation to bacteria. Beef, chicken, ham, pork, sausage, fish and shrimp treated by irradiation complete sterilization can be stored at room temperature (21 ℃ -38 ℃) for more than 2 years, and can maintain good color and flavor

irradiation disinfection and sterilization: the dose of 100-1000 kilorads can effectively limit the growth of organisms and destructive microorganisms that are harmful to public health, and can effectively remove the hazard load on high protein foods such as meat, dairy products, egg products, and small deformation (electronic extensometer) for automatic 4-level verification; So as to ensure that the accuracy does not exceed the maximum difference of Salmonella, with 500000 rads of irradiation, it can be 100 million times less by pressing the "start" button on the counter; It can also kill Salmonella in the depths of frozen food. At present, more than 20 countries in the world have approved the application of irradiation sterilization of food for human consumption, such as chicken, pork, fresh fish, mushrooms, spices, potatoes, rice, onions, wheat and so on. Irradiated food is safe and reliable. More than 40 years of practice in countries around the world has proved that irradiated food has never been found to have radioactive material residues, and can maintain its original quality, color and flavor. In the United States, irradiated food has been brought into space, and astronauts have proved to be harmless after eating it. The advantage of irradiated food is that it has a long storage period. One irradiation can keep fresh for several years, which not only kills bacteria, but also inhibits and delays the metabolism of the food itself, eliminating the root cause of food deterioration. Irradiation sterilization can save a lot of energy. After sterilization by irradiation, any food can be stored only in ordinary packaging, saving a lot of canning, refrigeration and other materials and energy. Irradiation preservation can replace some refrigerators for storage

ultraviolet irradiation: ultraviolet irradiation uses ultraviolet rays to kill the DNA of target microorganisms, causing them to undergo chemical changes to form pyrimidine dimers, so as to destroy genetic factors and lose the ability to reproduce or die. The sterilization effect is the strongest at 250nm-260nm. The powerful UV lamp developed abroad, with an irradiation intensity of 200MW/cm2, is a high-performance UV device, which is safe and effective for the sterilization of packaging materials

solid surface sterilizer: the packaged food is sent into the irradiation track through the conveyor belt, sterilized with a sterilization lamp, and then sent out by the conveyor belt. It is applicable to the food packed with plastic film, and the packaging material is required to use polyethylene or polypropylene plastic film with good light penetration

liquid sterilizer: it can be divided into two types: external irradiation type with external irradiation and internal irradiation type with water and liquid flowing from the inside. The bactericidal effect can reach zero after irradiation from the initial concentration

ultraviolet sterilization: ultraviolet sterilization requires no or only a small amount of fungicides and preservatives. Compared with heating treatment and filtration sterilization, it is energy-saving, low-cost, simple to maintain, safe and reliable to use, and does not damage the flavor and luster of this kind of material called microporous foam food after sterilization. It is widely used. The United States has successively developed a series of products. Ultraviolet lamps with radiation dozens of times larger than in the past have been put into practice and can be gradually used for transmission. Ultraviolet sterilization is better if it is combined with heating, hydrogen peroxide, hot citric acid solution, ethanol, ultrasound and other treatment methods

microwave sterilization: microwave sterilization is to use microwave to vibrate water molecules and use the friction heat generated by molecules to sterilize. It is suitable for food with poor heat conduction and food with poor quality due to heating. For the food with plastic packaging materials, it can be heated and sterilized from the food center in a short time under the original packaging, and it can also prevent secondary pollution. Microwave sterilization is only applicable to molds, yeasts, Escherichia coli and other heat-resistant microorganisms, but the effect is not significant for the microorganisms attached to the back of food with low moisture content and on plastic or glass without moisture and with small inducement, because the temperature cannot be fully increased

microwave heating method: there are two kinds of microwave heating methods: oven or tube type. The latter is used to treat liquid, which is heated through a glass tube obliquely penetrating the tube

aseptic packaging technology: aseptic packaging technology is a packaging technology that sterilized and cooled aseptic food can be stored for a long time after being filled into pre sterilized containers in a sterile state and sealed. In the past decade, aseptic canning has developed from fluid to solid, and packaging materials have moved from metal cans to packaging materials

aseptic packaging technology has developed rapidly in Europe, America, Japan and other countries, and is widely used in dairy products dominated by milk, processed foods such as fruit juice, pudding and meat, vegetable juice, broth, cool drinks, coffee drinks, soymilk and other fields

aseptic packaging has many advantages: less changes in product flavor, tissue color, nutrient loss and protein thermal denaturation, and aseptic packaged meat products have no fat precipitation and meat juice separation, which can better maintain the original taste and flavor; The fruit juice in sterile packaging is easy to keep, fresh, practical and convenient. Aseptic packaging has low requirements on the strength of packaging containers, and the materials can be cardboard, plastic, aluminum, etc. In particular, paper containers have low cost, light weight, no metal dissolution, can be discarded after use, and are simple to handle. 70% of American drinking milk is packed with paper. Aseptic packaging also has the advantages of saving energy and being suitable for mass production

aseptic packaging system includes two parts: sterilization of food and aseptic filling and sealing. Food sterilization usually adopts high-temperature short-time sterilization process (HTST method) and ultra-high temperature instant sterilization (UHT). The composite film composed of heat-resistant plastic film and aluminum foil can greatly shorten the sterilization time. The sterilization of flexible packaging materials for aseptic filling and packaging generally adopts ultraviolet sterilization, radiation sterilization, hydrogen peroxide solution immersion, spray, hot air drying, or gas fungicide sterilization

typical aseptic packaging devices in the world include aseptic canning of American Dole company, which is used for fluid, colloid and food containing solids in metal can packaging, such as a variety of pudding, condensed milk, sauce like food, yogurt fresh milk, etc. Aseptic canning equipment consists of four parts: sterilization of empty cans, filling, sterilization of tank covers, and sealing of cans. When the empty cans enter the sterile room after sterilization at 2100 ℃ and 220 ℃ for 45 seconds, sterile water is sprayed from the lower part to cool the empty cans. Generally, trough flow canning machines are used for continuous canning. The MM aseptic filling device in Japan is to sterilize the styrene plastic film with hydrogen peroxide, heat the forming film and punch it into a ring container, automatically fill it quantitatively, send out the aluminum foil for the cover sterilized with hydrogen peroxide, seal it with a sealing film, and cut off the blanking film, which is used for aseptic filling of pudding, jam, ice cream, milk, fruit juice, etc

in the process of aseptic packaging, in addition to the sterilization of packaging materials and packaged food, the whole operation of workshops, working machinery and air should be clean and sterile, so as to thoroughly realize the production management and circulation management of microbial control

at present, more applicable new sterilization technologies have also been developed. For example, the flame sterilization method of directly heating cans with gas flame during high-speed rotation can accelerate heat conduction and prevent uneven heating. It has a good effect when applied to canned food and steamed bag food; There is also a unique method of sterilization of liquid food with packaging materials without killing bacteria and simple food processing equipment; Using superheated steam to sterilize dry food by air flow method will not damp raw materials like saturated steam, and it is better for grains and powdered granular food

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