Surface and interior at the same time.
Conventional thermal sterilization starts from the surface of the material and then diffuses to the inside through heat conduction. There is a temperature difference inside and outside. In order to keep the flavor of food and shorten the processing time, the internal temperature of food is often not enough, which affects the sterilization effect. Because of the penetration of microwave, the surface and interior of food are affected at the same time, so disinfection and sterilization are uniform and thorough.
Easy to control
Microwave food sterilization treatment, the equipment can be used immediately, without the thermal inertia of conventional thermal sterilization, and the operation is flexible and convenient. The microwave power can be continuously adjusted from zero to rated power, and the transmission speed can be continuously adjusted from zero, which is convenient for control.
Simple equipment and advanced technology.
Compared with conventional disinfection and sterilization, microwave sterilization equipment does not need boilers, complicated piping systems, coal yards and transport vehicles, as long as it has basic conditions such as water and electricity.
Improve working conditions and save floor space.
The working environment of the equipment has low temperature and low noise, which greatly improves the working conditions. The whole microwave equipment only needs 2-3 operators. It is widely used for heating, drying and sterilizing beef jerky, pork breast, fish fillet, sauce meat, duck meat, chicken and other products. After microwave sterilization, the freshness, tenderness and flavor of meat products remain unchanged, and the hygiene index can be completely lower than the national food hygiene standard. Shelf storage time can reach 1-2 months. The successful application of microwave sterilization and preservation technology of meat products has extended the preservation period from 3 days to 1-2 months, and raised the technical achievements to a new stage.
Problems of microwave heating:
(a) Uneven microwave heating
1. Reasons for uneven microwave heating:
(1) Microwave heating is selective. Even in the same microwave field, different ingredients have different temperature rises.
(2) Microwave has good penetrability and is affected by reflection, penetration, refraction and absorption in actual heating, even though the heat energy generated by different parts of the same food may be very different;
(3) The sharp concentration of electric field, some of which are also called edge effect. As a kind of electric wave, microwave has sharp electric field concentration, which is the main reason for the uneven heating of food by microwave. The electric field will be concentrated in the corners, and these parts will generate more heat and heat up quickly. In order to overcome the shortcomings of water chestnut effect and hot spot, many improvements have been made to the container. For example, try to use round containers and ring containers with appropriate sizes. Plastic treatment of sharp food. In order to overcome the limitations of microwave heating, it is a new trend to combine microwave and far infrared heating methods.
(B) the impact of microwave on the human body
According to the principle of microwave, the human body will also absorb microwave, so microwave radiation will also cause some harm to the human body. Usually, when the human body is irradiated, the skin always feels hot first, so it can be avoided in time. However, when exposed to microwave radiation, because of its penetrability, the tissues in the body will also heat up at the same time, and there are fewer nerves in the human body, so those organs with low heat resistance have been damaged before they feel the heat. For example, blood vessels, eyes and testicles are vulnerable to microwave damage, and common diseases of radar workers include cataract and male infertility. Pay attention to safety when using microwave, but don't be too nervous as when treating radioactivity.
(3) microwave sterilization and bag breaking
In the process of microwave sterilization, in addition to paying attention not to use metal containers and aluminum-plated or aluminum-coated bags, there is also the problem that the sealed bags are broken during sterilization, which is difficult to solve. The seal is not good after sterilization. At present, microwave sterilization can be carried out before packaging or after packaging. When the packaged food is sterilized by microwave heating, because the pressure in the bag is too high, the packaging bag will burst, so the whole process of microwave heating sterilization should be carried out under pressure, or the discoloration of the package (4) should be treated in a pressurized glass container.