Views: 201 Author: Wendy Publish Time: 2023-05-09 Origin: Site
The effect of microwave on organisms as a polar medium to absorb microwave energy produces two effects: a thermal effect and a non-thermal effect (also known as a biological effect). The geothermal effect of microwaves on living organisms is the phenomenon of thermal denaturation of biological proteins and solidification (> 50 °C). The consequences are fatal for bacteria, which is the theoretical basis for pasteurization. This is the same as the pasteurization effect in terms of the thermal effect of microwaves on organisms. But microwave radiation goes far beyond that.
Microwave radiation is bidirectional in its interaction with living organisms. If the microwave dose exceeds the organism's heat resistance threshold, it will cause harm to the organism. But if it is lower than the threshold value, microwave radiation can play an active and catalytic role in the activities of living organisms. There are two physical environments for microwave sterilization: one is the temperature field of heat, and the other is the electromagnetic field with very high frequency. There are two kinds of physical fields acting on microorganisms, in which the electromagnetic force field sterilization plays the leading role.
Because the microwave can transmit inside the material, whether the material is liquid or solid, it can be sterilized in the microwave heating area together with the container. Of course, the condition is that the container of the material should not have a metal texture.
Liquid sterilization is a general microwave sterilization method applicable to material packaging or not, divided into packaging and after packaging sterilization. In filling before sterilization mode, the technical transformation investment is less. However, during the first filling and then sterilization treatment, the liquid material and the container are heated at the same time, which will inevitably increase energy consumption and require the container to withstand pressure after closure. However, if the use of sterilization before filling reduces energy consumption, it is necessary to have supporting aseptic filling technology and equipment, as well as container-separate cleaning and sterilization equipment.
Solid sterilization is generally appropriate for soft packaging materials. Due to the simultaneous sterilization, it can effectively avoid the recontamination of bacteria. In the conventional heating sterilization operation, vacuum packaging sterilization can be divided into three kinds: heating sterilization under vacuum; fully cooked products vacuum packaging after heating sterilization; and cooked products hot vacuum packaging. They can extend the price period of the product depending on the degree of heat treatment, PH value, moisture activity, salinity, and number of additives. To this end, the industry often adds preservatives to extend shelf life.