-China Jiangsu Network July 25th? At 1 1 last night, a couple suspected of eating expired junk food and died of poisoning. Then he was sent to the hospital with the help of his neighbors. The man died after being sent to the hospital, and his wife was seriously ill.

-Because some green leafy vegetables contain more nitrate, if they are left for too long after cooking, nitrate will be reduced to nitrite under the decomposition of bacteria, which is carcinogenic and cannot be removed by heating.

According to scientific determination, some overnight vegetables, especially overnight green leafy vegetables, not only destroy their nutritional value, but also produce pathogenic nitrite. The production of nitrite in stored vegetables increases with the increase of storage time and temperature, but if vegetables are stored in refrigerator (2-6 degrees Celsius), the increase of nitrite is less. It's winter now, and some families think it's cold, so leftovers don't need to be put in the refrigerator. This view is also wrong. The widespread use of refrigerators in cities has reduced the nitrite content people consume from food, but it doesn't mean that putting vegetables in the refrigerator can be completely assured; After a long time, the nitrite content will still increase. It is worth mentioning that different kinds of vegetables produce different amounts of nitrite under the same storage conditions.

-Many fried dishes can't be eaten or stored, especially some high-protein and high-fat leftovers. The harmful bacteria in the air will attach to the leftovers within 2 hours and start to multiply. As we all know, most protein and fat will produce harmful substances under the action of bacteria, such as hydrogen sulfide, amines, phenols and so on. It is harmful to human body. It is an indisputable fact that eating leftovers for a long time is easy to cause cancer. Therefore, you can't eat overnight dishes. When cooking, the best way is to tailor your clothes, not to harm your health!

-fried a dish in the evening, didn't finish it, and ate it the next day. It's called "overnight dish", of course. But, as someone asked, what if I eat in the middle of the night? What if I fry in the morning and eat at night? From the perspective of food science, staying overnight is not a problem. The essence of the problem is what happens to cooked vegetables during storage. We are worried that nitrate in vegetables will be converted into nitrite. This transformation process can be realized by the original reductases in vegetables, but in the process of cooking, these enzymes lose their activity and this road is cut off. Another way is the role of bacteria. Originally, the vegetables were cooked and the bacteria in them were almost killed. But in the process of eating, some bacteria will enter the leftovers on chopsticks; During the preservation process, some bacteria in the air may also enter. Cooked vegetables are more suitable for bacterial growth. Under appropriate conditions, they will grow in large quantities, and nitrate may be converted into nitrite during the growth process.

This process has nothing to do with the overnight interval, but only with the preservation conditions. Finally, how much nitrite will be produced in vegetables depends on the vegetables themselves; Secondly, under what conditions are cooked vegetables preserved; The third is how long it has been preserved.

It can be seen that "overnight dishes" may indeed produce carcinogen nitrite. If you leave the vegetables bought overnight, what's the difference between overnight and cooked? In this way, whether vegetables are cooked or cooked the next day, nitrite may be produced. Once produced, it cannot be removed.

-because vegetables have definite benefits to health, you can't stop eating them just because there are "possible" nitrates and nitrites. For many people, it is also common to buy vegetables for several days at a time. Therefore, preserving vegetables has become a very important issue in food hygiene.

The raw material of nitrite in vegetables is nitrate in vegetables, and the transformation condition is mainly bacterial growth. "Overnight" is only a matter of time. Reducing the production of nitrite can be done in a multi-pronged way. First of all, reduce the preservation time of vegetables, especially green leafy vegetables, and increase the frequency of buying vegetables. Secondly, vegetables that need to be kept fresh can be washed and wrapped to reduce the bacteria carried. Do the unfinished dishes well, or keep them sealed in the refrigerator.

"Overnight" is not the key to nitrite production, and heating will not increase the content of carcinogens. Of course, many vitamins in vegetables will be destroyed by heating, and vegetables heated many times are also unpalatable. From the perspective of "delicious", "overnight dishes" are really poor; From the point of view of nutrition, repeated heating is not good.

Must I not eat overnight dishes?

-In this era of health knowledge flying all over the sky, many people are actively or passively absorbing health-related knowledge, which has both advantages and disadvantages. On the bright side, people pay more attention to health than they did decades ago. This is a kind of progress in concept, which is the product of social development to a certain stage, that is, only when people have enough food and clothing can they focus on higher-level things such as maintaining health, otherwise they can only pay attention to food and clothing; The downside is that when all kinds of health-related knowledge appear in front of your eyes, you may not be able to tell whether it is correct with a professional eye. This may be misleading and even dangerous. Therefore, the knowledge we get from non-professionals or institutions is for reference only.

-Many people have heard that "you can't eat overnight dishes", so from a professional point of view, can you eat overnight dishes? To answer this question, we must know what happened to the overnight dish. Most plants contain nitrate, which is converted into nitrite by some enzymes in plants. Bacteria in the environment will also reduce nitrate in plants to nitrite, which will be converted into nitrosamines in human body. Nitrosamines are recognized as one of carcinogens.

As we all know, the activity of enzyme needs a certain temperature. After the vegetables are cooked, the enzymes in the vegetables will lose their activity. At this time, the enzymes in vegetables can no longer convert nitrate into nitrite, and then the bacteria are working. It takes some time for bacteria to reproduce. When it reaches a certain amount, it may produce a considerable amount of nitrite, which should be the root cause of the so-called "overnight dish", but we can also see that the problem is not overnight. It's time. Time is the key. Cooking in the evening/kloc-after 0/0,/kloc-after 0/2 is overnight. Would you say you can't eat? Or 1 in the morning, and 1 1 in the evening is the dish of the day. If you rigidly believe that the food of the day is all right, will you feel comfortable?

It can be seen that the problem lies in time, not overnight interval. Of course, this should also take into account the ambient temperature. The environmental temperature of the same pot of vegetables is different, and the number of bacteria reproduction at the same time may be different. Generally speaking, low temperature can inhibit bacterial reproduction. In this case, it is of little significance to simply consider that this dish is not overnight, because in natural environment, the temperature is high in summer and low in winter, and the summer dish may deteriorate before overnight, while the winter dish.

Overnight dishes are not suitable for eating.

It is said that the low incidence of gastric cancer is related to the habit of not eating overnight dishes. Because some green leafy vegetables contain more nitrate, if they are left for too long after cooking, nitrate will be reduced to nitrite under the decomposition of bacteria, which is carcinogenic and cannot be removed by heating.

Healthy eating "

—— Generally, the nitrate content of stem and leaf vegetables is the highest, while that of melon vegetables is slightly lower, with roots and cauliflower in the middle. Therefore, if you buy different kinds of vegetables at the same time, you should eat stems and leaves first, such as Chinese cabbage and spinach. If you are going to cook more vegetables and eat them hot the next day, try to make fewer stem and leaf vegetables and choose melons.

2. Pay attention to the storage of overnight soup.

-Many people like to make soup. Put the soup they can't finish in the refrigerator and cook it the next day before drinking it. Is this overnight soup good for your health?

Healthy diet: The best way to preserve the soup base is not to put seasonings such as salt. After the soup is cooked, scoop out what you want to drink that day with a clean spoon, and it is best to store it in the refrigerator with a clay pot. Because the leftover soup is stored in aluminum pot and stainless steel pot for a long time, it is prone to chemical reaction, so it should be kept in glass or ceramic utensils.

3. Bring your own lunch should be optional.

-Many people are tired of eating box lunch in restaurants and don't want to fight guerrilla warfare outside, so they choose to bring their own lunch. However, most of the meals we brought with us were from the night before. After a night and a morning of storage, the loss of nutrients in food is more serious, so when you bring your own food, you should also choose.

-The food you can bring is rice, beef, bean products, all kinds of non-green vegetables, fruits, yogurt and so on.

-To ensure enough energy for lunch, foods containing protein, vitamins and minerals are essential. Among vegetables, towel gourd and lotus root contain more cellulose. In addition, you can also choose celery, mushrooms, radishes and so on. When cooking, just fry the vegetables for six or seven minutes to prevent further damage to their nutrients when microwave heating the next day. Try to choose meat dishes with less fat, such as beef and chicken. After cooking, cover it immediately after cooling and store it in the refrigerator at 4℃. Take it to the office the next day and put it in the refrigerator immediately. At lunch, fully heat it in the microwave oven and eat it.

-Overnight foods that are not suitable for eating include fish, seafood, green leafy vegetables and cold salad. According to the Evening News, green leafy vegetables such as green vegetables and spinach are repeatedly cooked and fried each time, and the carcinogens in them increase dozens of times, which is extremely carcinogenic ... This morning, the "China-Japan International Symposium on Early Gastric Cancer" was held in Shanghai. According to experts, China has the highest incidence and mortality of gastric cancer. Half of the patients with early gastric cancer are asymptomatic, and the diagnosis rate is below 5%. "19 In the 1930s and 1960s, gastric cancer was also a high-incidence tumor in Japan, but with the popularity of refrigerators, people began to get used to eating it on the same day. Since the 1970s, the incidence of gastric cancer in Japan has dropped significantly. " Experts say that the high incidence of gastric cancer is related to improper eating habits, such as eating overnight dishes and returning to the pot. Experts said: "Green leafy vegetables such as vegetables, spinach, green beans such as kidney beans, (bean workers) beans and broad beans are repeatedly returned to the pot, and chlorophyll is prone to chemical reactions, producing degradable components, which is easy to cause cancer. Seafood such as crab, fish and shrimp can easily produce protein degradation products overnight, which will damage liver and kidney functions. The leftover soup is stored in aluminum pot and stainless steel pot for a long time, and it is also prone to chemical reaction, so it should be kept in glass or ceramic utensils. In addition, the refrigerator is not a fresh-keeping box, and fresh vegetables and fruits are easy to breed bacteria. As for pickled foods such as pickles, salted fish, ham, sausages and pickles, it is not advisable to eat more because of the carcinogen ammonium nitrite. " Experts remind the public that the daily diet should be light and fresh, do not eat overnight dishes, and eat more fresh pork and braised pork. Leftovers should not be stored for more than 12 hours, and water should not be boiled repeatedly. If the public finds that the upper abdomen often has discomfort such as fullness and pain, and gastritis and ulcers do not heal repeatedly, they should be admitted to the hospital in time. Regular gastroscopy is recommended for high-risk groups with family history over 40 years old.

Eggs cannot be eaten overnight.

Northerner: Yes, you can't see anyone selling tea eggs in the street! Southerners: No, especially men, because they will get intestinal gas/* * swelling.

-scientist: not necessarily! Because if the egg is not fully cooked, the immature yolk will be eaten overnight. Nutritious things can easily breed bacteria if they are not properly preserved, which is harmful to the body, such as gastrointestinal discomfort and flatulence. However, if the food (eggs) is cooked and properly sealed at low temperature (usually refrigeration temperature), it can generally be preserved for 48 hours. From the tips of scientists, we can know whether eggs can be eaten overnight depends not only on whether they are heated, but also on whether they are cooked for the first time. Only after the first boiled egg is cooked, it is no problem to cook it overnight. This is also the truth of tea eggs. Maybe you don't know that tea eggs are boiled twice, the first time is boiled, the second time is to break the egg skin, add tea and other accessories, and then cook. Some people like to eat soft-boiled eggs. That kind of egg can't be eaten overnight. Don't eat it even if it is cooked for the second time. Therefore, the eggs must be cooked in the future!

You can't drink overnight tea.

Protein and sugar in tea soup will become nutrients for bacteria and molds to reproduce. So people usually think that overnight tea can't be drunk.

You can't drink boiled water overnight

—— When tap water is boiled for 3 ~ 5 minutes, the content of harmful substances such as nitrite and chloride is the lowest, which is most suitable for people to drink. Nitrite can form carcinogenic nitrosamines in human body. Some experts have found that the nitrite content in boiled water is higher than that in raw water. In addition, if the boiling time is too long or repeated for more than 24 hours, the nitrite content will increase obviously. After standing in boiling water for 24 hours, the nitrite content is 65438 0.3 times higher than that when it was just boiled. China residents have the habit of drinking boiled water, and it is best to burn it now or only drink the boiled water of the day. Don't drink boiled water for too long. God, I always cook a lot of boiled water and drink it slowly. . . .

Can tremella be eaten overnight?

-tremella decoction is an advanced nutritional supplement, but after a night, the nutritional components will be reduced and harmful components will be produced. Because both the tremella cultivated indoors and the tremella cultivated in the wild of basswood contain more nitrate, if cooked for a long time, the nitrate will be reduced to nitrite under the decomposition of bacteria. When people drink this soup, nitrous acid naturally enters the blood circulation. Red blood cells in the blood contain hemoglobin, which can carry a lot of oxygen for the body's needs. Nitrite, on the other hand, oxidizes normal hemoglobin into methemoglobin, losing its oxygen-carrying ability, leading to the lack of normal hematopoietic function in human body.

Seafood can't stay overnight.

-Overnight foods that are not suitable for eating include fish, seafood, green leafy vegetables and cold salad.

-Fish and seafood can easily produce protein degradation products overnight, which will damage liver and kidney functions. Green leafy vegetables contain different amounts of nitrate. If it is overcooked or left for too long, not only will vegetables turn yellow and taste bad, but nitrate will also be reduced to toxic nitrite by bacteria, which will cause cancer. Cold salad is polluted during processing. Even if it is refrigerated, it may deteriorate overnight. It should be cooked and eaten now.

Don't eat bad home cooking overnight.

Pot-stewed and rotten vegetables are popular seasonal dishes for Shanghai residents. Many citizens also like to put leftover food with bad taste in the refrigerator for the night, but this practice has great food safety hazards. To prevent food poisoning, don't eat rotten goods braised overnight in spring and summer. Bulk braised pork should be eaten on the same day, not overnight. From the perspective of food safety, this is unsanitary. If possible, it is best not to eat bad goods overnight.

-food experts remind that even the food in the refrigerator is not absolutely "safe". Refrigerators are prone to mold and psychrophilic bacteria.

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