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Collaboration of Plus and MinusHow the principle of microwaving affects food
Kwak Young-yoon  |
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승인 2015.05.07  13:21:11
트위터 페이스북 구글 카카오스토리
USING FIRE to cook food was a turning point for humanity. Besides directly applying fire to food, many diverse methods of cooking were developed as time passed by, such as boiling in water, frying with oil, and so on. But still, there was no other cooking method possible without fire until the 20C. The invention of the microwave oven demonstrates how much humans have evolved in terms of utilizing technologies for basic needs. Microwave ovens may be considered the most scientific method of cooking best adapted to modern society.
The principle of the microwave oven
The microwave oven is an amazing invention in that it effectively makes use of nature’s laws. Its operation is actually quite simple. The fundamental principle of the microwave oven is to heat and take moisture out of food through microwaves. Consequently, the whole food will be heated, and this process is called dielectric heating. Microwaves are a kind of radio wave with a frequency of roughly 2.5 gigahertz, which means that they are absorbed by water but not by plastics and ceramics. Water has polarity because although the substance is neutral, hydrogen atoms which are +charged and oxygen atoms, - charged are cornered to each side. Thus, the neutral state of water is delicate and the state can be broken when water is exposed to an electromagnetic field.
When microwaves permeate into water, an interesting phenomenon happens. Molecules of + and - charge in the water are drawn to the microwave’s - and + charge respectively. Inside the molecule, hydrogen and oxygen atoms are attracted by microwaves, which vibrate. During this state, atoms rotate very fast, making molecules collide with each other while the atoms inside of them rearrange. The collision is called friction in scientific terms, which causes heat. Therefore, microwaves do not emit heat, but help food produce heat within itself. This trait of the microwave makes it seem like a very mysterious process - but the way of creating it is quite simple. Microwave ovens use magnetrons to produce microwaves, which consist of an antenna, magnet, anode and cathode. When a microwave oven is powered, an electric current goes into the magnetron, creating microwaves and releasing them inside the oven along the waveguide. The wall inside the microwave is made of metal, which reflects microwaves back to the food, to prevent them from escaping the microwave oven. The net on the window of the microwave oven is also made of metal for the same reason.
What happens to the food in a microwave oven?
Compared to other cooking devices, the microwave oven has distinct advantages, as it cooks with microwaves, not with fire. One advantage is that a microwave oven cooks food from the inside. A clear drawback of using fire for cooking is that fire can only cook the surface of food. If the cooking has not been done properly, the surface ends up burnt while the inside remains uncooked. When using a microwave oven, however, the inside and outside are cooked to the same degree, so there is no need to worry about burning the surface of food. Moreover, while the loss of nutrients during the process of cooking is inevitable in most methods, the microwave oven can minimize the damage. According to a famous chef in the United States, whose specialty is food safety, Catherine Adams Hutt, nutrients, especially minerals and vitamins, are vulnerable to a long cooking time and water. This is why salad is the best way to absorb the nutrients of vegetables. Hutt said that the best way to maintain nutrients in food is to minimize the amount of water used and the cooking time. A microwave oven seems to meet the conditions best. Due to these two characteristics, a microwave oven is a cooking method that makes food in a healthy manner.
However, disadvantages still exist. Since a microwave oven heats the water vapor inside the food, water evaporates from the food entirely. This is why food in a sealed container should not be cooked in a microwave oven. Water in the food would be heated and evaporated, increasing its volume. When the container cannot withstand the increase in size, it will explode in the oven. Also, if moisture in the food contributes to its taste, the food might lose its flavor when heated with the microwave oven because the surface of food will dry out. Another disadvantage or inconvenience would be that plastic containers should not be used when cooking with microwave ovens. This is because plastic containers release endocrine-disrupting chemicals (EDC) into the food. EDC is very dangerous to human beings because it interferes with vital systems and actions in the human body. Some products claim that they have passed the safety test, but EDC has not been perfectly analyzed. Since scientists are not certain about what exactly EDC is, the safety test is virtually meaningless.
Because of this uncertainty, there are many rumors regarding the microwave oven. Although not scientifically proven, there are some hypotheses that the microwave oven cooking method is harmful for humans. For instance, some scientists insist that microwaves actually change the property of food in a negative way, when atoms of + and - charge are rearranged. Also, there is a very popular belief that the microwave oven emits radiation to the people standing near it. While many people consider this belief as a concrete truth, it has not been proven either way. There is conflicting research regarding the danger of staying near a microwave oven when cooking with it. The problem is that scientists cannot scientifically disprove these rumors. Even though microwave ovens have passed the safety tests before they were generalized, it has not been very long since humans started to use them. Hence, microwave ovens might have unknown critical effects on the human body. Scientists cannot completely get rid of the possibility that microwave ovens might cause serious damage to humans, which surely is a problem. Therefore, the convenience of cooking with the microwave oven must be based on the acceptance of some possible risk factors.
Box 1: Tips for using the microwave oven
1.     To avoid the loss of moisture in the food, put a glass of water in the microwave with the food.
2.     Do not heat pizza and fried chicken with the microwave oven because it will become stiff. They are best when cooked on a fry pan at low heat.
3.     You can cook rice with a microwave oven. Put rice in water twice the amount of the rice. Cook in the microwave oven for three minutes. Leave for 30 seconds then cook for three more minutes. Then you will have a delicious bowl of rice.
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   A microwave oven is a necessity for busy people these days. It is convenient; its cooking time is short and it is safer than using a flame method if precautions are taken. However, its safety is not yet guaranteed completely. Additional research about a microwave oven’s effects on food would later verify if a microwave oven is harmful to humans, as some scientists have suggested. Nevertheless, that does not mean that the usage of microwave ovens should completely be avoided. After all, any modern technology has a possibility of possessing unknown risks. Just as the microwave oven is a collaboration between plus and minus, it seems that it gives us both convenience and a slight bit of uncertainty 

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