What is the Principles of Microwave Sterilization

Microwave sterilization equipment is mainly used in the pharmaceutical and food industries to sterilize various small packaged food, bottled food, bottled drinks, cakes, biscuits, preserved fruit, bean products, cooked food, condiments (chicken essence, essence), flour, etc.

Microwave has dual bactericidal effects, both thermal and non thermal, coupled with ultraviolet light waves, to achieve the goal of sterilization. The brief introduction of the sterilization mechanism of microwave thermal effect is that biological cells are a condensed medium composed of complex compounds such as water, proteins, carbohydrates, fats, and organic substances. The temperature of this medium increases under the action of a strong microwave field. Its spatial structure undergoes changes or destruction, and the protein denatures, affecting its solubility, viscosity, expansibility, and stability, thereby losing its biological activity. The mechanism of microwave non-thermal effect sterilization is summarized as follows: Microwave action can change the state of biological alignment polymerization and its movement rules, and the ion flow induced by microwave field can affect the distribution of electric charges near the cell membrane, leading to damage to the barrier function of the membrane, affecting its function. Produce membrane dysfunction that interferes with or breaks the normal metabolic function of cells, leading to bacterial growth inhibition, cessation, or death. In addition, RNA and deoxygenation (DNA) in cells can cause relaxation, breakage, or recombination of hydrogen bonds under microwave field forces. Induce gene mutations or chromosomal aberrations, thereby affecting changes in biological activity, delaying or interrupting the stable inheritance and proliferation of cells. The radiation intensity of the UV light wave tube exceeds 8 uW/cm2 (1 meter from the surface of the tube), and the ozone concentration reaches 38 mg/m3 (30 minutes, under dynamic equilibrium state). Due to the fact that the single ozone produced by D-band ultraviolet radiation in the air is completely different from the ozone produced by high-voltage discharge (which also produces extremely harmful nitrogen oxide compounds), ultraviolet tubes that can generate pure ozone and have direct radiation sterilization are rapidly replacing traditional ozone generators.

Briefly speaking, microwave sterilization is the result of the combined action of microwave thermal and non thermal effects. The thermal effect of microwave mainly plays a rapid warming and sterilization role, while the non thermal effect uses the protein and physiologically active substances in the microbial body to mutate, leading to loss of vitality or death. Therefore, the microwave sterilization temperature is lower than that of conventional methods. Generally speaking, the sterilization temperature of conventional methods should be above 100-120 degrees Celsius, and the time should be between 10 minutes and dozens of minutes. However, the microwave sterilization temperature is only between 70 and 90 degrees Celsius, and the time is about a few minutes (for example, the total number of bacteria in bean products is about 60000 to 70000, after microwave sterilization, the total number of bacteria is only below 6000, and the coliform group is less than 30, and the time is about 15 minutes to meet the requirements for food sterilization).

The shelf life of foods processed by microwave sterilization can be extended by 3 to 8 times without damaging their original nutritional components, color, taste and natural flavor. Compared with other drying, sterilization and thawing equipment, it can reduce the floor area and energy consumption by 30% to 100%, and does not produce "three wastes" pollution.