First, microwave food sterilization mechanism Microwave is an electromagnetic wave in the range of 100MHz to 100000MHz. The temperature field of microwave sterilization is compared with the electromagnetic field. The electromagnetic field is the main cause of bacterial death, especially at lower temperatures. The experiment gives people a revelation that making full use of the changing electromagnetic field will enable a new means and technology for sterilization at lower temperatures, creating an effective sterilization route that can both sterilize and maintain the flavor and quality of the food. In general, electromagnetic field sterilization refers to an electromagnetic field in the frequency range of 104 to 1011 Hz. The electromagnetic field in the sterilization process shows that "non-thermal factors become the leading cause of bacterial death" breaks the pattern of conventional heat sterilization, and the object that the bacteria wants to survive and needs to fight is changed to "electromagnetic force". There are various hypotheses for the mechanism of pulsed electromagnetic field sterilization. To sum up, the bactericidal mechanism of pulsed electromagnetic is mainly manifested in the following two aspects: electric field action: The main biological research of molecules shows that most molecules and atoms in living organisms have polar (equivalent electric dipole) and magnetic properties ( Molecular current model), so the addition of an electromagnetic field will inevitably have an effect or effect on the organism. Under the action of an external electromagnetic field, the electric dipole and molecular current are oriented along the direction of the electromagnetic field. In an electrostatic field, only a new final state is established; but in a time-varying electromagnetic field, electric dipoles and molecular currents vibrate as the electromagnetic field changes. Obviously, the influence of the applied electromagnetic field with different intensity distributions on different organisms is different. In the medical field, it has been found that the cell body has an abnormal performance in an electromagnetic field, and the typical performance is a response to electromagnetic waves. This biological response occurs away from equilibrium, and the effects of organisms on electromagnetic fields that satisfy certain conditions are nonlinear and exhibit frequency-specific functions and power specificities. The energy of the effect sometimes comes from within the biological system, and the external electromagnetic field only acts as a trigger. Cells are the most basic unit of life, and cell membranes are the most studied part of cells. There is a certain potential difference inside and outside the cell membrane. Under the action of the applied electric field, the potential difference between the inside and outside of the membrane will increase, the permeability will increase, the cells will penetrate, and the treatment will continue moderately. When the electromagnetic field reaches a certain value (E>EO When H>HO), the cell membrane undergoes irreparable rupture, a phenomenon called electroporation. At the same time, since the electromagnetic field is changed, the frequency and intensity of the electromagnetic field will change greatly in a very short period of time, and an oscillation effect is generated on the cell membrane. Irreversible electroporation and intense oscillating effects can rupture cells, which cause cell structure disorder, thereby killing cells and killing bacteria. Ionization: The dielectric resistance of a changing electromagnetic field has an inhibitory effect on the microorganisms of food. Under the action of the external electromagnetic field, the charged particles in the food space will produce high-speed movement, impacting the food molecules, causing the food molecules to decompose, producing yin and cations. At the same time, the electrolyte electrolyzes the cations and cations. These cations and cations are extremely active under the action of strong electromagnetic fields, and pass through the cell membrane which has been improved in permeability, and interacts with living substances such as proteins and RNA in the microorganisms, thereby blocking the normal biochemical reaction and metabolism in the cells. . In addition, the electromagnetic field can break the hydrogen-oxygen bond of water molecules, and generate excessive superoxide anion radicals, hydrogen peroxide, and free protons in water. Hydrogen peroxide, on the other hand, has a strong oxidizing effect on biological molecules, which destroys DNA and causes cell death. Ozone generated by ionization in a liquid medium also has a strong oxidation effect and can react with a series of intracellular substances. The combination of the above two effects constitutes a major factor in killing bacteria. Second, microwave food sterilization advantages 1. Short time and fast speed: Conventional thermal sterilization is transmitted from the surface of the food to the inside through heat conduction, convection or radiation, and it takes a long time to reach the sterilization temperature. The microwave uses its transmission effect to combine the heat effect and the non-thermal effect to uniformly and rapidly heat the bacteria inside and outside the article. The processing time is greatly shortened, and even under a strong power density intensity, even a few seconds to several tens of seconds can achieve satisfactory results. 2, low temperature sterilization, maintaining material composition: rapid heating of the microwave thermal effect and biochemical effects of non-thermal effects, enhance the sterilization function. Compared with conventional thermo-sterilization, the sterilization effect can be obtained at a relatively low temperature and in a short period of time. The general sterilization temperature is 75-80 ̇C, and the treatment time is 3-5 minutes. Microport has a processing method that retains more active ingredients and maintains the original color, aroma, taste, shape and other flavors. For example, the conventional treatment of vegetables with vitamin C is 46-50%, microwave treatment can reach 60~90%; if conventionally heated pig liver vitamin A is maintained at 58%, while microwave heating is 84%. 3, energy conservation: microwave electromagnetic conversion rate is high, generally more than 70%, better than the heating electric efficiency. In addition, the microwave directly converts the magnetic heat energy to the food, and the microwave heater itself is not heated, so there is no additional thermal power consumption, so energy saving, compared with 30 to 50% of power saving. 4, even and thorough sterilization: conventional thermal sterilization is started from the surface of the biological material. Through heat conduction, gradually heating from the inside and outside of the table, there is a temperature difference gradient inside and outside, resulting in inconsistent internal and external sterilization effects, the thicker the problem becomes more prominent. In order to maintain the flavor of the food and shorten the processing time, it is necessary to increase the processing temperature to shorten the processing time, but this will reduce the color, fragrance, taste, shape and the like of the food surface. The penetration of the microwave allows the surface and the interior to be heated at the same time to ensure uniform sterilization inside and outside. 5, easy to automate production: microwave equipment is easy to operate, no thermal inertia, can be controlled in real time according to the production process requirements. The entire production line requires only 1 or 2 operators. 6, advanced technology: microwave sterilization equipment does not require boilers, complex piping systems, coal yards and transportation vehicles, etc., only basic conditions of water and electricity, no special requirements for the plant. Less investment and quick results. 7. Saving floor space: microwave equipment has no high temperature residual heat, does not generate heat radiation, can improve the working environment; and the equipment is compact in structure and saves plant area. Third, the typical application of food sterilization The application of microwave sterilization in the food industry began as early as 1976. According to a Japanese company, the microwave power capacity for food sterilization such as cakes and rice noodles has accounted for 34% of the total industrial microwave. At the same time, in Sweden, Germany, Denmark, Italy and other countries, microwave sterilization has long been used on the packaging line of sliced ​​bread. Because the bread slices are contaminated by mold in the air during the cooling process, the bread preservation period is greatly shortened. . A Swedish company installed a 2450 MHZ bread sterilizer to process 4,400 lbs of bread. The temperature of the microwave-treated bread increased from 20 ° C to 80 ° C in just 12 minutes. The treated bread was preserved from the original. The 3~4 days are extended to 30~40 days. The daily food company in the Netherlands uses microwave technology to preserve the boxed fish, meat and food. The product is evenly heated to 72 ° C ~ 75 ° C, and can be stored in a 0 ~ 4 ° C freezer for 6 weeks to ensure the original flavor Fresh as ever, the price is close to frozen food. The treatment volume is 1500 kg ╱ hours. Since the 1970s, China has started research and application of microwave sterilization of traditional Chinese medicine, grain and other nutritious foods. In the processing of various bagged foods and natural nutrients, vacuum freeze-drying and cobalt 60-ray sterilization processes are usually used to maintain various nutrients and microorganisms. The defects are complicated process and long production cycle. The equipment investment is large, the radioactive residue affects the scope of use, and the energy consumption is high and the efficiency is low. The microwave penetration performance, does not destroy the nutrients and low temperature sterilization characteristics, is suitable for such food processing. We use 2450MHz 10Kw microwave drying sterilizer to treat pollen. The production practice shows that the processing time is shorter than the original process, the product quality is good, the sterilization temperature is low, and the nutrient composition is maintained. The efficiency is increased by several times and the power is saved by 92.5%. The product has been exported to Hong Kong, Singapore, Japan and other places. Currently, the equipment is also widely used in ginseng, soy milk powder, nutritional granules, medicinal materials, etc. The 20Kw microwave food sterilization machine can sterilize the cooked foods such as smoked fish, chicken, duck and floss, and its production capacity is 250Kg?h, and the sterilization effect is good. If the Cantonese-style pork is processed at 28 ° C, the shelf life can be extended by 7 days. Now this type of technology has been promoted and applied to fish products, soy products, meat products, pickles, beverages and other manufacturers. A company in Wenzhou uses our company's microwave equipment to produce fish fillets, which are not only heated and dried, but also sterilized and killed. Originally used far-infrared roast fish fillets, the daily output of 1.5 tons, power consumption 40Kw?h, the current microwave only need electricity 17Kwh, energy saving more than 50%, the fish fillets are more crisp and delicious. And completely solved the problem of mildew. Sichuan uses microwave equipment to treat sesame oil and dried bean special products. After vacuum packaging, it can be stored for several tens of days without deterioration at room temperature. Sterilization is the most important process in the milk production process. The traditional method is to use high temperature short-time pasteurization. The shortcomings are the need for huge boilers and complex piping systems, high energy consumption, large coal yards, high labor intensity, and environmental pollution. Microwave liquid sterilizer is used to sterilize milk. The processing power of 10KW microwave power is 125-200kg╱h. After the fresh milk is treated at 80°C for several minutes, the bacteria and coliform bacteria fully meet the national health standards, not only nutrition. The composition remains unchanged, and the diameter of the fat globules which are subjected to microwave action becomes smaller, and there is a homogenization effect, which increases the flavor of the milk and sweat, and is beneficial to the absorption of nutrients. Especially in recent years, some food manufacturers in Hunan and other provinces use industrial microwave to treat pickles such as scallions and mustard, which simplifies the original processing technology, is simple and convenient to operate, saves energy, improves efficiency, and achieves satisfactory results.