Microwave oven is one of the common household appliances in daily life, which is mostly used for reheating and heating food. Some consumers worry that using microwaves to cook or reheat food is unsafe and that the nutritional content of the food will change. Are these concerns based on science? How should consumers scientifically understand and correctly use microwave ovens in daily life?
How microwave ovens heat food
Microwave refers to the frequency of 300 MHZ ~ 300 GHZ, wavelength in the range of 1 mm ~ 1 meter. Microwave frequency is higher than radio waves, lower than infrared, visible light and ultraviolet radiation, belonging to non-ionizing radiation electromagnetic wave.
Microwave oven refers to a civil or industrial electrical appliance that uses electromagnetic waves in the microwave frequency band to heat materials. The electromagnetic energy is converted into heat energy after the food absorbs the microwave. Through the rotation of the stirrer and the reflection of the inner wall of the furnace, the food can be heated efficiently from all directions.
The principle of microwave heating is different from that of cooking, frying and other conduction heating methods that rely on heat transfer from high temperature heat sources. Because there is no need for heat transfer medium, there is no loss of heat transfer, and the food is heated inside and outside at the same time, with the advantages of fast heating speed, high efficiency and small thermal inertia.
Effects on human health
A large number of scientific experiments have confirmed that buying microwave ovens that meet national standards from regular channels and operating them correctly is safe and will not affect human health.
Microwave radiation is different from X-ray or gamma rays, it is a non-ionizing radiation electromagnetic wave, frequency wavelength and common radio waves in our lives (radio, television, navigation, etc.) close, and microwave photon energy is extremely weak, far below the weak interaction between molecules, can not destroy molecular covalent bonds, will not destroy the structure of matter, Therefore, there is no need to worry about microwave radiation risk.
Microwave ovens are manufactured and designed with metal walls and metal mesh, which can limit the microwave in the microwave oven cavity and avoid microwave leakage. Therefore, microwave ovens that meet national standards are safe and consumers can use them with confidence.
In fact, whether it is traditional cooking or microwave heating, when the temperature is too high and the time is too long, it may produce some substances that are harmful to health.
Compared with other heating methods, microwave heating can improve the heating rate, shorten the heating time, and is more conducive to the retention of food nutrients.
Use should pay attention to matters
Before using the microwave oven, read the instructions carefully and use correctly.
Microwave foods include nuts with skin or shell, eggs with skin, closed packaged foods, etc., which cannot be directly put into the microwave oven for cooking or reheating.
The internal expansion of these foods is faster than the external heat, and after heating, it will quickly produce a lot of water vapor, which cannot be released, and it is easy to produce high pressure, causing food explosion.
Grapes, cherry tomatoes and other foods with high water content and similar shape and size can not be heated in the microwave oven, otherwise it is easy to generate plasma flame under the microwave field, causing a fire.
Containers should be carefully placed in the microwave oven containers should be selected for microwave oven special plastic containers, or non-metallic glass and ceramic containers.
Any packaging containers or utensils containing metal should not be heated in the microwave oven, including tin foil, aluminum foil, etc. Microwaves will reflect when they meet metal, easily puncture microwave sources, and even cause explosions. At the same time, avoid using a completely closed container, otherwise the heat is not easy to release during the heating process, which can easily lead to too high pressure in the container, causing burst and scalding.
The heating operation should be standardized according to the type and state of food, reasonable selection of heating time and microwave firepower, and it should not be over-heated for a long time under high power. If you do not know how much power and how long to use heating, it is preferred to choose low power for a short time.
In addition, it is not appropriate to use microwave to boil liquid food for a long time, otherwise it is easy to produce boiling, splashing and other phenomena. At the same time, it should also be noted that it is strictly prohibited to idling the microwave oven, so as not to cause fire or even explosion.
