Application of the hottest and coldest sterilizati

Application of cold sterilization technology in packaging and food processing machinery

consumers' requirements for food are generally safe to eat, stable in nature, and without additives. In traditional food processing, thermal sterilization is mainly used, which leads to the destruction of nutrients, intensified discoloration and loss of volatile components. Cold sterilization (physical sterilization) is a new kind of technology with the accuracy of contemporary experimental force reaching 1%, and the accuracy of anchor chain elongation measurement also reaching 1%. The physical sterilization conditions are easy to control, and the external environmental impact is small. Because the temperature of food does not rise or rise very low in the sterilization process, it is conducive to maintaining the physiological activity of food functional components, as well as the color, aroma, taste and nutritional components, Therefore, it is very necessary to adopt cold sterilization technology in the design and manufacture of packaging and food machinery

■ ultra high pressure sterilization technology

this is a sterilization technology developed in the late 1980s. Food has good sterilization effect under ultra-high pressure of 100 ~ 1000MPa. The lethal effect of ultra-high pressure on microorganisms is mainly achieved by destroying their cell walls, coagulating proteins, inhibiting the activity of enzymes and the replication of genetic substances such as DNA. Generally speaking, the higher the pressure, the better the sterilization effect. Prolonging the compression time under the same pressure does not necessarily improve the sterilization effect. Under the pressure of 400 ~ 600MPa, it can kill bacteria, yeasts and molds, avoiding the adverse changes caused by general high-temperature sterilization. The progressiveness of ultra-high pressure "cold sterilization" technology is high-pressure and normal temperature sterilization. After using this technology to treat food and beverage, it not only has high sterilization efficiency, but also can retain the nutrients in food and beverage intact. The product has good taste, natural color, high safety and long shelf life, This is an advantage that the traditional high-temperature thermal sterilization method does not have

food ultra-high pressure processing technology can not be more detailed. It is known as "a revolution in the food industry" and "today's top ten cutting-edge technologies in the world". It can be applied to all solid or liquid foods containing liquid components, such as fruits, vegetables, dairy products, eggs, fish, meat, poultry, fruit juice, soy sauce, vinegar, alcohol, etc. Ultra high pressure food meets the consumption needs of new food in the 21st century. 12. The sample is simple, safe, natural and nutritious. It is believed that it has a huge replacement market and broad development prospects

■ UHV pulsed electric field sterilization

it uses the pulsed electric field generated by the high-voltage pulser to sterilize. The alternating action of electric field and magnetic field generated by the pulse increases the permeability of cell membrane and weakens the membrane strength. Finally, the membrane is broken, the substances inside the membrane flow out, the substances outside the membrane penetrate, and the bacterial body dies. The effect of electromagnetic field produces ionization, blocks the normal biochemical reaction and metabolism of cell membrane, and changes substances in bacteria. Many researches have been made on this technology at home and abroad, and corresponding treatment devices have been designed to effectively kill dozens of bacteria related to food corruption. Some manufacturers in France and the United States have put this new technology of cell destruction by electric field into practice, avoiding a series of shortcomings such as protein denaturation and vitamin damage caused by heating

■ strong magnetic pulse sterilization technology

this technology uses the biological effect of strong pulse magnetic field to sterilize. Outside the infusion tube, there is a spiral coil, and the magnetic field intensity of (2 ~ 10) t is generated in the magnetic pulse generator circle. When the liquid material passes through the infusion pipe, the bacteria in it will be killed. The technology has the following characteristics: short sterilization time and high sterilization efficiency. The sterilization effect is good and the temperature rise is small. It can not only sterilize, but also maintain the original flavor, taste, color, fragrance, quality and components (vitamins, amino acids, etc.) of food. It does not pollute the environment, does not pollute products, has no noise, is economical and practical, and is an ideal green product. It has a wide range of applications and can be used for the disinfection and sterilization of various liquid materials before canning (or packaging), such as alcohol products (beer, yellow rice wine, low alcohol koji wine, various fruit wines, etc.), liquid foods (such as milk, soymilk, fruit and vegetable juice drinks), as well as mineral water, purified water, tap water and other drinking water

■ pulse strong light sterilization

pulse strong light sterilization is a technology that uses the method of intense white light flash of pulse for sterilization. Its most basic structure is the power unit and the inert gas lamp unit. The power unit provides energy to the inert gas lamp unit to make the inert gas lamp emit ultraviolet to infrared light with stronger intensity, which is opposite to the solar spectrum, for sterilization. Pulsed light uses extremely short pulses of high-intensity white light to kill microorganisms on the surface of food. The high-intensity white light is similar to sunlight, but it is only reflected at a fraction of a second. It is stronger than sunlight and can quickly kill bacteria. Under the strong pulsed light, the microbial lethal effect is obvious, and it can be used for thorough sterilization. During operation, different light intensity and time should be controlled for different foods and different strains

■ microwave sterilization

microwave is an electromagnetic wave with a frequency from 300MHz to 300gmhz. Microwave directly interacts with materials to convert UHF electromagnetic waves into heat energy. Microwave sterilization is the result of the combined action of microwave thermal effect and biological effect. The potential distribution of microwave on the bacterial membrane section affects the concentration of electrons and ions around the cell membrane, thus changing the permeability of the cell membrane. Therefore, bacteria are malnourished, unable to metabolize normally, and their growth and development are hindered and die. From a biochemical point of view, nucleic acid (RNA) and deoxyribonucleic acid (DNA) that bacteria normally grow and reproduce are coiled macromolecules closely connected by several hydrogen bonds. Microwave causes hydrogen bond relaxation, breakage and recombination, thus inducing genetic gene or chromosome aberration, or even breakage. Microwave sterilization uses electromagnetic field effect and biological effect to kill microorganisms. Practice has proved that the microwave device has obvious advantages in sterilization temperature, sterilization time, product quality maintenance, product shelf life and energy saving

■ radiation sterilization

radiation isotopes usually emit a β、γ Of the three kinds of rays, only γ Rays. γ Ray is a kind of electromagnetic wave with extremely short wavelength, which has strong penetration to objects. The cytoplasm of microorganisms is at a certain intensity γ Under X-rays, no structure is unaffected, resulting in mutation or death. The nucleic acid metabolic ring of microbial metabolism is inhibited by radiation, and the protein denaturates due to irradiation, which will cause the greatest damage to its reproductive function. Radiation does not cause temperature rise, so this sterilization method is called "cold sterilization". Microorganisms are generally resistant to radiation, and bacteria with high resistance to heat are also resistant to radiation, but there are exceptions

■ ultraviolet sterilization

sunlight can kill bacteria, mainly due to the role of ultraviolet light. Its sterilization principle is that microbial molecules are in an unstable state after being excited, thereby destroying the unique chemical combination between molecules and causing bacterial death. Microorganisms have different sensitivities to different wavelengths of ultraviolet light, and the lethal dose of ultraviolet light to different microorganisms is also different. Gram negative non bacillus is the most sensitive to ultraviolet light. The amount of ultraviolet radiation to kill gram-positive cocci needs to be increased by 5-10 times. Due to the weak penetration of ultraviolet light, it is suitable for sterilization of air, water, thin-layer fluid products and the surface of packaging containers

■ ozone sterilization

ozone has strong oxidation power, second only to fluorine, and can quickly decompose harmful substances. Its sterilization ability is 600 ~ 3000 times that of chlorine, and it can be quickly reduced to oxygen after decomposition. Ozone technology using its performance has long been widely used in developed countries such as Europe, America and Japan. It is the preferred technology in sterilization, sewage treatment, water purification, food storage, medical disinfection and so on. Researchers in the medical treatment of wood flour at the University of Washington found that ozone can inhibit the growth of cancer cells; Japan's ishikawashima boma heavy industry company has proved that ozone water is expected to become the best fruit and vegetable fungicide, and its germicidal effect is significantly better than sodium hypochlorite; Research by the Chinese Academy of Medical Sciences has proved that ozone can effectively kill Neisseria gonorrhoeae and decompose heavy metals in water. Experiments have proved that ozone water is a broad-spectrum bactericide, which can effectively kill general bacteria such as Escherichia coli, Bacillus cereus, dysentery bacillus, typhoid bacillus, meningococcal meningitis, influenza bacteria, hepatitis virus and other microorganisms in a short time. It can kill and oxidize various microorganisms that can produce changes on the surface of fish, meat, fruits and vegetables, and food, as well as microorganisms that continue to carry out life activities after fruits and vegetables are separated from their mother, accelerate the maturation of ethylene gas, extend the preservation period, and wash vegetables, fruits and fruits with ozone water, which can effectively remove the residual pesticides, bacteria, microorganisms and organic substances on their surfaces, and solve the hidden dangers brought by pesticides to people, At the same time, the secondary pollution caused by washing fruits and vegetables is avoided; It can completely kill bacteria in water, eliminate organic matter, purify drinking water, remove peculiar smell and odor in water and cleaned objects, and decompose heavy metals

■ ultrasonic sterilization

ultrasound with a frequency of more than 9 ~ 20 kHz/s has a destructive effect on microorganisms. It can make the contents of microbial cells subject to strong vibration and destroy cells. It is generally believed that hydrogen peroxide can be produced in aqueous solution due to the action of ultrasound, which has the ability of sterilization. Some people also believe that when microbial cell fluid is affected by high-frequency sound waves, the dissolved gas in it turns into small bubbles, and the impact of small bubbles can rupture the cells. Therefore, ultrasound has a certain killing effect on microorganisms

high energy ray sterilization technology high energy ray sterilization is a sterilization method that uses the radiation emitted during the decay of radioactive elements Co60 and CS17 as the irradiation source. The technology used for cold sterilization is ionizing radiation, which will produce direct and indirect effects in the process of irradiation; The direct effect is the ionization and chemical action of the microbial stroma after being irradiated by high-energy electrons; The indirect effect is that water ionizes after receiving rays, and then interacts with other substances in the cell. These two effects block all activities in the cell and lead to the death of microorganisms. For different strains, controlling different irradiation doses will not damage the color, aroma and taste of food; There will be no non food substance residues, and the sterilization effect is obvious. Therefore, at present, this sterilization technology is mostly used in meat products, fruit preservation and water treatment

■ low temperature conditioning sterilization

France has developed this sterilization technology especially for conditioning dishes. They mixed the ingredients of the dishes in bags and carried out low-temperature conditioning and sterilization under vacuum, which could avoid the adverse impact on the quality of finished products caused by repeated heating and sterilization. In recent years, Japan has developed low-temperature inflatable packaging sterilization technology, which can also be applied to some prepared foods

■ biological preservation

is considered as a natural preservation method. The use of anti microbial or natural fungicides to control the growth of pathogenic bacteria and mycotoxin native fungi in food. This is one of the more active research and development fields in food biotechnology, which has great development and application prospects

■ active packaging

refers to packaging technology with special functions other than the performance of conventional packaging. For example, add components with oxygen absorption function to the packaging materials, so as to eliminate the oxygen around the food during the storage period of packaged food, so as to meet the requirements of food safety preservation. Compared with traditional packaging, active packaging is a new packaging concept. It is through