Relevant knowledge
1. Short time and fast speed
Conventional thermal drying and sterilization is to transfer heat from the surface of an object to the interior through heat conduction, convection or radiation. It often takes a long time to reach the required dryness and sterilization temperature inside the object. The medium is composed of polar molecules and non-polar molecules. Under the action of electromagnetic field, these polar molecules change from the original random distribution state to the orientation according to the polarity of the electric field. Under the action of high-frequency electromagnetic field, these orientations change continuously according to the frequency of alternating electromagnetic field. This process causes the movement and mutual friction of molecules to generate heat. At this time, the field energy of the alternating electric field is converted into the heat energy in the medium, which makes the temperature of the medium rise continuously. Therefore, microwave heating is caused by the loss of the electric field energy of the dielectric material itself. Therefore, the microwave heating treatment time is greatly shortened. Under a certain power density intensity, the satisfactory effect can be achieved as long as tens of seconds or minutes.
2. Low-temperature drying, sterilization and nutrition maintenance
Microwave has the dual sterilization effect of rapid heating and non-thermal effect. Compared with conventional thermal drying and sterilization, it can obtain the required drying and sterilization effect at a relatively low temperature and a relatively short time. The general sterilization temperature is 65-70. C，75—80。 C or 103-121. In C, the time is 3-8 minutes, and it can retain more food nutrients and flavor such as color, fragrance, taste and shape. For example, the vitamin C retained in vegetables treated by conventional heating is 46-50%, compared with 60-90% of vitamin C retained by microwave treatment, 58% of vitamin A retained in pig liver by conventional heating, and 84% by microwave heating.
3. Save energy
Microwave power conversion efficiency is high, generally more than 70%. Microwave is used to directly treat food. The heating box itself is not heated, so there is no additional heat loss. Therefore, it can save energy and electricity, which can generally save 30-50%.
4. Uniform and effective
Conventional thermal drying and sterilization start from the surface of the material and then transfer to the inside of the material through heat conduction. There is a temperature difference between the inside and outside of the material, and the consistency of the inside and outside drying and sterilization effect is poor. In order to maintain the flavor and shorten the processing time, the internal temperature is often not enough to affect the drying and sterilization effect. This phenomenon can be improved by increasing the treatment temperature, but this will reduce the quality of the color, fragrance, taste and shape of the surface. Microwave has penetrating performance, the surface and the interior act simultaneously, and the internal and external temperatures can reach the required value together, so the drying and sterilization are uniform.
5. Easy to control and realize automatic production
The microwave food drying and sterilization treatment equipment is easy to operate, easy to control, and has no thermal inertia. It can be processed according to the requirements of different food process specifications, reducing production operators and production costs.
6. Simple equipment and advanced technology
Compared with conventional sterilization, microwave equipment does not need boilers, pipeline systems, coal yards and transportation vehicles, as long as it has the basic conditions of water and electricity, and has no special requirements for the plant, with less investment and quick results.
7. Improve working conditions and save floor space
The microwave equipment is free of high temperature, heat and thermal radiation. It can greatly improve the working conditions, and the equipment structure is compact, saving the workshop area.