The Mechanism of Microwave Sterilization and Preservation:
Microwave sterilization and freshness preservation are the hope that microwave treatment of food can make microorganisms such as fungi and insect pests lose their vitality or death, and ensure that the amount of bacteria in food during a certain storage period does not exceed the allowable range stipulated by the health law, thus prolonging its shelf life. The mechanism of microwave sterilization and freshness preservation is summarized as follows:
It is well known that bacteria and adults, like any biological cell, are a condensation medium composed of complex compounds such as water, protein, nucleic acid, carbohydrate, fat and inorganic biology. Among them, water is the main component of biological cells, with a content of 75-85%, because all kinds of physiological activities of bacteria must be participated by water, and the process of bacterial growth and reproduction, the absorption of various nutrients is accomplished through the diffusion of cell membranes and osmotic adsorption. Under the action of a certain intensity of microwave field, insects and fungi in food can also absorb microwave energy at the same time because of molecular polarization relaxation. Because they are condensate media, the interaction between molecules intensifies the energy state transformation of microwave energy. Thus, proteins in vivo are affected by both non-polar thermal motion and polar rotation, and their spatial structure is changed or destroyed, while their proteins are denatured. After denaturation, the solubility, viscosity, expansibility, permeability and stability of protein will change significantly, and lose its biological activity. On the other hand, the non-thermal effect of microwave energy plays a special role in sterilization which is not found in conventional physical sterilization. It is also one of the causes of bacterial death. It is the thermal or non-thermal biochemical effects of the microwave energy mentioned above that interfere with the normal metabolic functions of the parasites and bacteria, destroy their production conditions and delay the speed of genetic reproduction to achieve the purpose of insecticidal and sterilization.
Characteristics of donut microwave sterilization machine:Short time, fast speed.Conventional thermal sterilization transfers heat from food surface to interior through heat conduction, convection and radiation. It often takes a long time to reach the required sterilization temperature. Microwave sterilization is the direct interaction between microwave energy and microorganisms such as food and bacteria. Because of the combined action of thermal and non-thermal effects, the treatment time is greatly shortened.Low-temperature sterilization to maintain nutrient composition and traditional flavor.Microwave sterilization causes the variation of proteins and physiological active substances in the material, which results in the delay and death of the growth and development of microorganisms, and achieves the purpose of food sterilization, insecticide and freshness preservation.
Conventional thermal sterilization often requires heating through the environment or heat transfer medium to transfer heat to food. Microwave is directly used to treat food, so there is no additional heat loss. Generally, it can save 30-50% electricity. Conventional thermal sterilization starts from the surface of the material and then conducts through heat to the interior. In order to maintain the flavor of food and shorten the processing time, the sterilization effect is often affected by insufficient temperature inside the food. Microwave is the whole treatment of food, the surface and the interior are affected at the same time, so the sterilization is uniform and thorough. Microwave food sterilization equipment is easy to operate, easy to control, no control time inertia. Simple equipment and advanced technology.Compared with conventional disinfection and sterilization, microwave sterilization equipment does not need boilers, complex pipeline systems, coal yards and transport vehicles, as long as it has basic water and electricity conditions.
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