Is it dangerous to microwave food?
The same two pots of green plants, one was watered with purified water, the other was watered with microwave-heated water after cooling, and eventually, the latter died after 9 days.
An experiment that was popular a few years ago has reappeared on the Internet, and the experimenter wants to use this to show that microwave heating food can cause harm to the human body. Regarding this experiment, Qiao Yongjin, a researcher at the Agricultural Products Preservation Research Center of the Shanghai Academy of Agricultural Sciences, said in an interview with reporters yesterday that water molecules contain nothing but hydrogen and oxygen atoms. substance. However, he also said that heating food in a microwave oven will indeed cause some nutrients to be lost, but this is the same as cooking in a pot.
“Microwave water” experimental post online heat transfer
A post on a forum that reprinted a foreigner’s experiment appeared, with pictures and text—— Two pots of green plants, one pot was watered with microwave-heated water after cooling, and the other pot was watered with purified water. In the first 4 days, there was no big difference between the two pots of plants; on the 5th day, the plants watered with “microwave water” began to wither; on the 7th day, the plants watered with “microwave water” completely withered; on the 9th day, the plants watered with “microwave water” Plants watered with “microwave water” rotted even their roots. And throughout the 9 days, the plants that were watered with purified water thrived. The experimenter wanted to use “microwave water” to kill plants to illustrate that heating food in microwave ovens may cause harm to humans.
On another forum, a domestic netizen also posted the text and pictures of his own experiments, saying that “after reading the experiments and reports conducted by foreigners, out of curiosity and I want to prove it myself.” This netizen chose mung beans as the experimental object, and used “microwave water”, purified water, and tap water to grow mung bean sprouts. On the 8th day of the experiment, the mung beans watered with “microwave water” were still sprouting. On the 15th day, the stems and leaves of the mung beans watered with “microwave water” had just protruded out of the mouth of the disposable cup, while the mung beans watered with pure water and tap water had grown stems and leaves. The stems and leaves of the watered mung beans have protruded a long distance from the mouth of the cup.
Similar posts have appeared on several forums recently, sparking a discussion on “is it safe to microwave food”.
The “harmful microwave oven theory” is a “rehearsal”
After investigation, the reporter found that all the remarks about the “harmful microwave oven” actually originated from An article published on a website in the United States many years ago. On September 17, 2003, this article was translated and published by a well-known domestic media. The author of the original article cited an example of a patient in the United States who died after a blood transfusion that had been microwaved. After the incident, the family took the hospital to the court. The author declared, “This is the first time that there is significant evidence that microwave ovens have caused fundamental damage to the chemical properties of the heated items.” Through Internet searches, the reporter saw the court records at that time.
In addition, the author also cited the research of scientists in Switzerland, the United States, the former Soviet Union and other countries, trying to prove that heating with microwave ovens will change the molecular structure of food, destroy the nutrients contained in food, and even cause food to cause cancer. thing. The reporter logged on this website in the United States yesterday and found that the website is a purely commercial website that promotes various health care products. In addition to the various product introductions it sells, there are also some health science articles on the website.
Expert: Microwave Heating Foods Is Harmful and Unfounded
At that time, a well-known domestic media translated and published an article on an American website, which caused a lot of repercussions in China Fang Zhouzi, who has done postdoctoral research in the Department of Biology at the University of Rochester and the Salk Institute for Biological Studies, and is now mainly engaged in writing and website construction, has written articles to refute the views in the article.
The reporter saw in Fang Zhouzi’s article that, first of all, the author of the original article is not a scientist at the Massachusetts Institute of Technology, but only attended the school. More than a decade ago, he founded a company specializing in promoting health products, and the article was the promotional material on the company’s website, which contained many common-sense errors and logical fallacies. Regarding the medical accident of the blood transfusion, Fang Zhouzi explained that it is now forbidden in the medical community to use ordinary microwave ovens to thaw frozen plasma, because when ordinary microwave ovens are heated, due to uneven heating, local overheating is prone to occur, and once the blood temperature rises to Hemolysis occurs above 40°C. It can be seen that the medical accident was completely caused by local overheating when melting plasma, not the toxicity of microwave heating itself.
The experiments of scientists from various countries cited by the author of the original text were eventually proved to be inconsistent with the rigor of science.
In addition, authoritative departments such as the State Food and Drug Administration, the National Household Appliances Quality Supervision, Inspection and Testing Center, as well as experts from research institutions and universities such as the Chinese Academy of Sciences and Tsinghua University also said that microwave heating of food is unfounded. .
Food-preservation experts answer questions for readers
As for whether microwave heating food will spoil it? Qiao Yongjin, a researcher at the Agricultural Products Preservation Research Center of the Shanghai Academy of Agricultural Sciences, answered the reporter.
1. The experiment of watering dead plants with “microwave water” is not credible
After listening to the reporter’s description of the experiment of watering dead plants with “microwave water” on the Internet, Qiao Yongjin was a little surprised: “Myself I haven’t done a similar experiment myself, and with common sense, it seems unlikely.” Qiao Yongjin pointed out that if tap water is heated in a microwave oven, it is mainly water molecules H2O, and there are two kinds of atoms, hydrogen and oxygen. , others may also contain some minerals, no matter how heated it is, it is impossible to produce H2O2 (hydrogen peroxide), a harmful substance, at most, the water evaporates after heating, the salt content may increase, and the CO2 (carbon dioxide) in the air is more soluble For water, water has a certain degree of acidity. Even so, plants cannot be watered to death. “Is it true that the plants used in experiments are particularly intolerant to salt and acid?”
2. Microwave heating is easy to cause heat resistance Poor Nutrient Loss
Is there a loss of nutrients in food when microwaved? Qiao Yongjin said that this cannot be generalized, it depends on which foods are heated. “For example, heating foods containing more vitamin C in a microwave oven, such as vegetables and fruits, will lead to the loss of vitamin C, but if such foods are fried in a pot, it will also lead to the loss of vitamin C, because vitamin C is resistant to Nutrients with poor heat properties.” Qiao Yongjin explained that this is the reason why some vegetables and fruits can be eaten raw to absorb more nutrients, because the nutrients they contain are not heat-resistant. However, Qiao Yongjin pointed out that there are times when heating food in the microwave can bring a lot of benefits. For example, after making the food hot and soft, it is beneficial to the human body to absorb, especially the middle-aged and elderly people.
Qiao Yongjin explained that the principle of microwave heating is to change the electric field through the microwave generator in the furnace, so that the molecules in the food rotate at a high speed and collide with each other to generate heat to heat the food. During this process, the microwaves are absorbed and all converted into heat energy. Once the microwave oven is turned off, the microwave generator stops producing microwaves, and the microwaves disappear immediately.
3. Prolonged heating of certain substances may be harmful
However, heating certain substances in microwave ovens may be harmful. For example, Qiao Yongjin said, such as meat, because it contains more protein, and once the protein is overheated, it is easy to produce carcinogens, such as ammonium nitrate. “But it’s the same as grilling meat, where charred meat can contain carcinogens. It’s not a microwave problem, it’s a problem with too much heat.
Compared to whether microwave heating of food is harmful, another concern is microwave radiation. Some domestic experts believe that there is evidence to prove the harm of microwave radiation to the human body, which is certain, but after taking appropriate protective measures, microwaves can be widely used in communication, remote sensing and other fields to benefit human beings; Harmful to the human body, there is currently a lack of convincing evidence.
It is reported that high-intensity microwave radiation can burn the skin, make the eyes more sensitive, and may cause cataracts. However, microwave ovens have multiple insurances to prevent microwave leakage, and the radiation generated by microwave ovens when working is even smaller than an ordinary fluorescent tube.
International and national standards stipulate that microwave leakage from microwave ovens must be controlled within 5 milliwatts per square centimeter at a distance of 5 cm from the microwave oven, which is not strong enough to cause any damage to the human body, and in fact, The microwave leakage of microwave ovens produced today is lower than the national standard.
