Wang Mingyong (dietotherapy health expert) Different nutrients are suitable for different cooking methods, such as water-soluble vitamins and minerals, chlorophyll, vitamin C and potassium, but not suitable for high-temperature heating and boiling environment. The longer the cooking time, the more nutrients are lost. Therefore, the cooking time should be shortened as much as possible, so as not to lose nutrition and maintain the taste of food. At present, the scientific community has found that the three nutrients in food will produce carcinogens as long as they are overheated. Protein will produce heterocyclic amines or heterocyclic amines, oil will produce polycyclic aromatic hydrocarbons, and starch will produce carcinogens such as acrylamide. ◎ Cold food: The biggest advantage of eating raw food is that it can retain more nutrients and consume less calories, which can achieve the effect of losing weight. In addition, fresh fruits and vegetables are rich in water and fiber, which can promote smooth defecation, reduce blood lipid, delay the increase of blood sugar and prevent colorectal cancer. A study by USDA found that most fresh fruits and vegetables lose vitamin B and C after heating and cooking, except carrots, tomatoes and spinach. After carrots were cooked, the antioxidant content increased by about 30%, while after tomatoes were cooked, the contents of vitamins A and C increased by about 20%, while the content of vitamin C decreased by 65%. Uncooked raw food may taste bad. Raw food is mostly cold and may not be suitable for everyone. In addition to organic and pollution-free ingredients, raw food may have problems such as eggs and microorganisms, and it is easy to eat microorganisms and parasites. Therefore, patients with chronic diseases, such as cancer and kidney disease, are not suitable for eating completely raw, but can be eaten after scalding. Wang Mingyong (dietotherapy health expert) Different nutrients are suitable for different cooking methods, such as water-soluble vitamins and minerals, chlorophyll, vitamin C and potassium, but not suitable for high-temperature heating and boiling environment. The longer the cooking time, the more nutrients are lost. Therefore, the cooking time should be shortened as much as possible, so as not to lose nutrition and maintain the taste of food. At present, the scientific community has found that the three nutrients in food will produce carcinogens as long as they are overheated. Protein will produce heterocyclic amines or heterocyclic amines, oil will produce polycyclic aromatic hydrocarbons, and starch will produce carcinogens such as acrylamide. ◎ Cold food: The biggest advantage of eating raw food is that it can retain more nutrients and consume less calories, which can achieve the effect of losing weight. In addition, fresh fruits and vegetables are rich in water and fiber, which can promote smooth defecation, reduce blood lipid, delay the increase of blood sugar and prevent colorectal cancer. A study by USDA found that most fresh fruits and vegetables lose vitamin B and C after heating and cooking, except carrots, tomatoes and spinach. After carrots were cooked, the antioxidant content increased by about 30%, while after tomatoes were cooked, the contents of vitamins A and C increased by about 20%, while the contents of vitamin C decreased by 65%. Uncooked raw food may taste bad. Raw food is mostly cold and may not be suitable for everyone. In addition to organic and pollution-free ingredients, raw food may have problems such as eggs and microorganisms, and it is easy to eat microorganisms and parasites. Therefore, patients with chronic diseases, such as cancer and kidney disease, are not suitable for eating completely raw, but can be eaten after scalding. What foods can't be eaten raw? 1. Leguminous foods such as soybeans, black beans and red mung beans: Raw food containing leguminous saponins can cause nausea, gastrointestinal inflammation, diarrhea and other symptoms. 2. Pod food: Kidney bean, kidney bean and pea pods contain trypsin inhibitor and hemagglutinin. , will prevent trypsin from decomposing protein into amino acids, leading to indigestion, not suitable for raw food. 3. Spinach and perilla: The content of oxalic acid is high, and it is easy to hinder the absorption of calcium when eaten in large quantities for a long time; Poor liver and kidney function is more likely to affect liver function and even cause acute renal failure. 4. Grain: contains raw starch and minerals such as calcium phytate and magnesium, which cannot be absorbed by the human digestive system unless cooked. 5. White radish, cruciferous vegetables (such as cabbage, cauliflower, cauliflower, cabbage, etc.). ): These nutritious vegetables all contain substances that cause goiter, which is easy to hinder the role of thyroid gland in iodine. If eaten raw for a long time, it may cause goiter, and heating can greatly reduce it. 6. Drupe: raw walnuts, almonds and peanuts are easy to be allergic, so people with allergies are not suitable for raw food. ◎ Cooking method: 1. Steaming: the original molecular structure of food cooked by steam is less destroyed, and the original flavor and nutrients of food are retained to the maximum extent. However, it should be noted that the time should not be too long, so as not to cause nutrient loss. Many steamed vegetables can be steamed in 3 to 5 minutes, but root vegetables, fish and eggs take longer. If you are in a hurry, you can also cut the vegetables into smaller pieces or slices and steam them for 10 to 20 minutes. 2. Boiling: This method can preserve the state of food without increasing too many free radicals. However, the nutrients in vegetables (such as vitamin A in carrots) will be lost after cooking for a long time, and the more broken the food, the more serious the loss of nutrients. The University of Warwick studied cruciferous vegetables (broccoli, cauliflower, cabbage and cabbage) with different cooking methods, and found that after boiling in water for 30 minutes, the anticancer components of these vegetables lost at least 50%. It is suggested that the cooking method of "boiling water" should not exceed 5 minutes, which is not a burden to health. 3. Stewed soup: One advantage of stewed soup is that many nutrients will enter the soup, and at the same time, the nutrients will decompose and be easy to digest. But it will destroy antioxidants, vitamin B group and vitamin C over time, so it is best to choose slow stew. 4. Stir-fry: This is the most commonly used cooking method in China. Unlike frying, it uses less oil and the temperature is not that high. Many people are used to waiting for the pot to be "hot enough" before putting food into it. The so-called "hot enough" means that the oil in the pot smokes and exceeds the smoking point. At this time, the oil has reached a high temperature, which is easy to crack, and greasy oil is easy to stick to the range hood or kitchen wall. After breathing, it will enter the respiratory tract, which may increase the risk of cancer in the respiratory tract for a long time. If we can control the oil consumption, stir-fry the food more and make the heating surface of the food uniform, we can avoid producing too much oil smoke. Or change the cooking order of "oil, vegetables and water" to "water, vegetables and oil" to minimize the harm of lampblack! 5. Microwave heating: The temperature generated by microwave heating is extremely high. Heating for a long time will destroy the nutrients in food, especially the food with high oil content, and will also produce a lot of free radicals, so it is necessary to avoid heating for a long time. Microwave is a kind of radiation, so many people naturally think it will cause cancer. Microwave electromagnetic waves are essentially the same as radio waves, infrared rays and visible light used in radio and telegraph. The only difference is the frequency. The safety of microwave is the same as that of sunlight-whether it hurts the human body depends on the strength of energy and how much energy the microwave reaches the human body, so try to stay away from it when using the microwave oven. Another safety problem when using microwave ovens is that heating plastic containers will release harmful substances. The FDA (Health and Welfare Department of the US Food and Drug Administration) has measured the amount of harmful substances that may be released from various plastic containers during normal microwave heating, and it is required to be less than 1% or even 1% of the harmful dose determined by animal experiments before it can be marked as "microwave-heatable". Therefore, the "microwave heating" plastic container that passed the FDA inspection is quite safe. If you are still worried, it is safer to use white ceramic or glass containers for microwaves. 6. Barbecue: When the meat is barbecued in the oven, the smell is quite attractive, but with the smell, the vitamins and amino acids in the meat are also destroyed, and the protein changes qualitatively, which will affect the intake of vitamins, protein and amino acids in severe cases. What's more, when the nucleic acid in meat decomposes with most amino acids in Maillard reaction, it will produce gene mutation, which may lead to cancer. Because barbecue fire will produce smoke, free radicals and carcinogens produced by high temperature will stick to barbecue meat and then enter the human body. In addition, in the barbecue environment, some carcinogens will enter the human body through the skin, respiratory tract, digestive tract and other ways, and then induce cancer lesions. 7. Frying: Fried food tastes delicious and fragrant, so it is widely loved by Asians. But the frying temperature is usually too high, which will destroy the antioxidants in food and reduce the vitamin content. For example, there are more B vitamins in meat, which will be reduced by 30%~40% when fried. In addition, this method will increase free radicals and even carcinogens. When edible oil is reused, the situation is more obvious, and the oil is more prone to rancidity. Call on everyone not to cook food with cooking oil! The researchers also found from animal experiments that frying oil heated for more than 20 hours can produce hepatotoxicity. We can control the oil consumption at home, but modern people have more and more opportunities to eat out. Faced with snack vendors and catering businesses, it is difficult to ask for a complete ban on the reuse of edible oil. Based on cost considerations, it is also difficult for snack vendors and catering businesses not to use cooking oil. So pay special attention to eating out. (1) frying oil is dark in color and thick in texture. (2) When heated, bubbles are generated, which are difficult to disappear. (3) More oil smoke is produced, and the smoke point is reduced, indicating that the oil has deteriorated. (4) Starch foods such as French fries and fried dough sticks are dark brown instead of golden yellow. (5) The frying oil has obvious oil consumption smell. (6) The surface of the bombed object looks oily, and the oil can't be dispersed if it adheres to it. In either case, it shows that the oil quality has deteriorated to the point where it can no longer be used, and it is time to replace it with new oil. Restaurants can buy oil test paper to test edible oil. When the acid value exceeds 2.0, it is time to change the oil. Wang Mingyong fan group, Wang Mingyong blog.