Application of the hottest industrial microwave ov

The application of industrial microwave ovens in the food industry

I: introduction to microwave sterilization

microwave refers to the electromagnetic wave with the frequency of 300 MHz to 300 GHz. Under the action of microwave electromagnetic field, the polar molecules in the medium change from the original thermal motion state to the arrangement orientation following the alternation of microwave electromagnetic field. For example, if the microwave frequency is 2450 MHz, there will be 2.45 billion alternations per second, Produce intense friction and heat. In this microscopic process, microwave energy is converted into heat energy in the medium, which makes the medium temperature rise macroscopically

microwave has double bactericidal effects of thermal effect and non thermal effect. The brief description of the sterilization mechanism of microwave thermal effect is that biological cells are a condensed medium composed of complex compounds such as water, protein, nucleic acid, carbohydrate, fat and organic compounds. The temperature of the medium rises under the action of strong microwave field. Its spatial structure changes or destroys, and the protein denatures, which affects its solubility, viscosity, expansibility and stability, thus losing its biological activity

the brief description of the sterilization mechanism of microwave non thermal effect is: microwave action can change the biological arrangement and polymerization state and its movement law, and the ion flow induced by microwave field will affect the charge distribution near the cell membrane, resulting in the damage of the barrier function of the membrane, affecting the function of Na-K pump, producing membrane dysfunction, thus interfering with or destroying the normal metabolic function of the cell, leading to the inhibition, stop or death of bacterial growth. Moreover, ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) in cells can lead to relaxation, breakage or recombination of hydrogen bonds under the action of microwave field force. Induce gene mutations or chromosomal aberrations, thus affecting the changes of its biological activity, delaying or interrupting the stable inheritance and proliferation of cells

simply speaking, microwave sterilization and preservation are the result of the combined action of microwave thermal effect and non thermal effect. The thermal effect of microwave mainly plays the role of rapid temperature rise and sterilization; The non thermal effect uses the proteins and physiological activities in the microorganism to help the stepless, automatic, double clutch and other variable speed systems (cvt/at/dct) reduce the weight, and the weight of substances change, resulting in loss of vitality or death. Therefore, the microwave sterilization temperature is lower than that of the conventional method. Generally, the sterilization temperature of the conventional method is more than 100 degrees, and the time is more than ten minutes to dozens of minutes, while the microwave sterilization temperature is only 70 to 90 degrees, and the time is about a few minutes

advantages of microwave sterilization in food enterprises:

1. Short time and fast speed: conventional thermal sterilization transfers heat from the surface of food to the interior through heat conduction, convection or radiation, which often takes a long time to reach the sterilization temperature inside. Microwave uses its transmission effect to make the inside and outside of the object heat up evenly and quickly to kill bacteria with the combined action of thermal effect and non thermal effect. The processing time is greatly shortened, and the satisfactory effect can be achieved as long as a few seconds to tens of seconds under strong power density

2. Low temperature sterilization and maintaining its nutritional components: the rapid warming of microwave thermal effect and the biochemical effect of non thermal effect enhance the sterilization function. Compared with conventional thermal sterilization, the effect of insect killing and sterilization can be obtained at a relatively low temperature and in a short time. Generally, the sterilization temperature is 75 ~ 80 ℃, and the treatment time is 3 ~ 5 minutes. The unique processing method of microwave can retain more effective ingredients and maintain the original color, aroma, taste, shape and other flavors. For example, the vitamin C retained in vegetables treated with conventional heat is 46-50%, and microwave treatment can reach 60-90% on March 18; Vitamin A in the liver of pigs was kept at 58% by conventional heating and 84% by microwave heating

3. Energy saving: microwave heating efficiency is high, generally more than 80%, which is far better than other heating methods. In addition, microwave directly converts the magnetothermal energy of food, and the microwave heater itself will not be heated, so there is no additional thermal power consumption, so it saves energy and electricity, which is 30-50% compared with energy saving

4. Sterilization is uniform and complete: conventional thermal sterilization starts from the surface of the material. Through heat conduction, it is gradually heated from the outside to the inside. There is a temperature gradient inside and outside, resulting in inconsistent sterilization effects inside and outside. The thicker the problem is, the more prominent it is. In order to maintain the flavor of food lubricated with No. 100 oil and shorten the treatment time of the classification method of burning performance of building materials GB8624 ⑴ 997, it is necessary to increase the treatment temperature in exchange for shortening the treatment time. However, this will reduce the quality of the food surface, such as color, aroma, taste and shape. The penetrability of microwave makes the surface and interior heated at the same time to ensure uniform sterilization inside and outside

5. Easy to automate production: microwave equipment is easy to operate, has no thermal inertia, and can be adjusted and controlled in real time according to the production process requirements. The whole production line only needs 1-2 operators

6. Advanced technology: microwave sterilization equipment does not need boilers, complex pipeline systems, coal yards and transportation vehicles, but only the basic conditions of water and electricity, and there are no special requirements for plants. Less investment and quick results

7. save floor space: microwave equipment has no high-temperature waste heat, does not produce thermal radiation, and can improve the working environment; Moreover, the equipment structure is compact and the plant area is saved

II: introduction to microwave heating and drying

microwave is an electromagnetic wave with penetrating characteristics with a wavelength range of 1mm-1m and a frequency range of 300-300kmhz. The commonly used microwave frequencies are 915MHz and 2450MHz. Microwave drying technology relies on the periodic change of microwave at the speed of hundreds of millions of times per second through the material, and interacts with the polar molecules of the material. After the polarity of the material (such as water molecules) absorbs the microwave, it changes its original molecular structure, and also makes the polarity movement of the electric field at the same speed, resulting in frequent collisions between each other and a large amount of friction heat, so that all parts of the material obtain heat energy at the same moment and heat up, Water evaporation occurs successively to achieve the purpose of drying

advantages of microwave heating drying in food enterprises

a, fast drying speed

conventional drying is to transfer heat from the surface of materials to the interior through heat conduction, convection or radiation. For example, flame, hot air, electric heating, steam, etc. they gradually increase the temperature of the material center, which is called external heating and drying. It takes time for the central part to reach the required temperature, and it takes longer for substances with poor thermal conductivity. Microwave heating and drying is to make the heated material itself become a heating body, which is called internal heating method. It does not need the process of heat conduction, and the inside and outside are heated at the same time. Therefore, the heating effect can be achieved in a short time

b, uniform heating and drying

conventional heating and drying, in order to improve the heating speed, it is necessary to increase the heating temperature, which is easy to produce external coke endogenous phenomenon. When microwave heating and drying, all parts of the material evenly penetrate electromagnetic waves and generate heat. Therefore, the uniformity is greatly improved

c, energy saving and high efficiency

in microwave heating and drying, microwave energy is only attracted by the heated object itself to generate heat, and the heating chamber wall and the air in the heating chamber and the corresponding containers will not generate heat, so the thermal efficiency is very high, and the production environment is significantly improved

d, simple operation, high selectivity

microwave equipment is ready to use, without the thermal inertia of conventional equipment, flexible and convenient operation, microwave power is continuously adjustable, and the transmission speed adopts electromagnetic or frequency conversion speed regulation, which is easy to control. The circuit control system adopts bus control mode and can be configured with advanced infrared remote control and pulse function, which is convenient and safe

e, safe and harmless

generally, microwave energy refers to the transmission in the closed heating chamber and waveguide made of metal. Our company uses advanced design to strictly control the microwave leakage at the inlet and outlet, observation window, furnace door, etc. within the national safety standard indicators. Microwave does not belong to radioactive rays, and there is no harmful gas emission. It is a very safe heating technology. (end)