Eating leftovers can cause cancer? Chemist: Everything about cancer is a hooligan.

After the Spring Festival, leftovers have become a problem that almost every family has to solve. It's a pity to dump it. If you eat hot food, you are worried about the risk of cancer. The reason why people suspect that leftovers cause cancer is nothing more than: leftovers will produce nitrite+nitrite will cause cancer = eating leftovers will cause cancer? Is that really the case? Pharmacists should say: all infinite carcinogens are hooligans!

Generally speaking, the nitrite content in most leftovers that have not been placed for a long time (more than 2~3 days) is lower than the national standard. From the general environment, it is very rare to eat leftovers occasionally to cause cancer, so don't worry too much. But pharmacists still have to remind: try not to eat or eat less leftovers. Although the probability of cancer is low, gastroenteritis and food poisoning often occur because of eating leftovers!

Let's talk about leftovers first.

1. The taste is getting worse. I believe everyone has a deep understanding of this, so I won't say much.

2. Loss of nutrition. After repeated heating, antioxidants and some vitamins (vitamin C, B group, folic acid, etc. ) will be seriously lost.

3. The content of nitrite increased. The longer you put it, the higher it rises. In particular, there are many nitrates in leafy vegetables, which are easily converted into nitrite under the action of bacteria. After the fried vegetables were left at room temperature for 24 hours, the nitrite content was 5~6 times of the original.

4. Bacterial reproduction. Harmful bacteria in the air easily attach to some high-protein and high-fat leftovers, producing substances harmful to human body, such as hydrogen sulfide, amines, phenols and so on.

Let's talk about which meals can be saved. What can't stay?

Try not to eat leftover food;

1. leafy vegetables

There are many nitrates in vegetables, which can be easily converted into nitrite under the action of bacteria. The nitrite content of the same vegetable is different, the leafy vegetable is the highest, the melon is slightly lower, and the rhizome and cauliflower are in the middle. It was found that the nitrite content of leafy vegetables increased obviously after being stored at room temperature for 12 hours, which greatly exceeded the national safety limit. Even if it is put in the refrigerator, it can only delay this process and cannot completely stop the increasing trend of nitrite. Cool vegetables, especially those that are not heated or mixed raw, would rather be wasted than eaten.

2. seafood

Protein of aquatic products is particularly easy to be synthesized by microorganisms, which reduces the nutritional quality and is more likely to breed harmful microorganisms and produce nitrite.

Other foods only need to be thoroughly heated before eating. It is no problem to keep 1 ~2 days (no more than 3 days), but you should still pay attention. The sooner you eat, the better

If there are indeed leftovers to be disposed of, the following points should be noted:

1) Leftovers should be thoroughly cooled before being put in the refrigerator. It is because hot food suddenly enters the low temperature environment, and the hot air of food will cause water vapor condensation, promote the growth of mold, and cause the whole refrigerator food to be moldy. After thorough cooling, put it in the refrigerator in time, even in winter, and don't leave it outside for a long time, because the refrigerator has certain antibacterial effect.

2) Meat dishes are easy to grow bacteria for 2 hours. Harmful bacteria in the air will attach to some high-protein and high-fat leftovers and reproduce within 2 hours. Protein is the best culture medium, which can make bacteria multiply, and bacteria can make protein and fat produce harmful substances such as hydrogen sulfide, amines and phenols. These substances are harmful to human body. Therefore, leftovers should be put in the refrigerator within two hours after cooking and put in shallow containers to facilitate cooling.

3) Don't spend the night for leafy vegetables. Some overnight vegetables, especially overnight green leafy vegetables, not only have low nutritional value, but also produce pathogenic nitrite. Therefore, if there are different kinds of vegetables left at the same time, you should eat leafy vegetables, such as Chinese cabbage and spinach, instead of overnight vegetables. Cold dishes are best eaten at one meal, not every other meal.

4) Don't leave food for 6 hours. Leftovers are best eaten within 5~6 h, and the storage time of leftovers should be no eating, that is, eating leftovers at noon in the morning and eating leftovers at night at noon; If the food is stored for too long, the bacteria in the food will release chemical toxins, even if it is heated, it has nothing to do with these toxins.

5) Rice and noodles should not exceed 4 hours. Foods rich in starch, such as rice and noodles, are best eaten within 4 hours. If you don't eat it in a short time, don't eat it again, even if the appearance has not deteriorated. Because starchy foods such as rice and noodles are easily parasitized by staphylococcus, and the toxins of these bacteria are not easy to decompose at high temperature. It is best to eat rice with stir-fried dishes, at most every meal, but not overnight. Therefore, people often say that fried rice with eggs is the best with overnight meals, which is absolutely not desirable!

6) The food stored in the refrigerator must be returned to the pot after being taken out. It needs to be heated for a longer time before eating again, and it is better to add some ingredients. This is because the temperature of the refrigerator can only inhibit the reproduction of bacteria, but not completely kill them. The heat penetration of meat food is relatively slow. When the volume is large, if the heating time and temperature are not enough, the sterilization effect can not be achieved, which may cause abdominal pain, diarrhea and even food poisoning.

Fish and seafood dishes are the best hotbeds of Escherichia coli, so it is necessary to reheat them thoroughly with wine, onion and ginger. It not only keeps fresh, but also has bactericidal effect.

(2) Meat such as livestock and poultry should be heated with vinegar, because this kind of food is rich in minerals, which will overflow with water after heating, but calcium acetate will be synthesized when it meets acetic acid, which not only improves the nutritional value of food, but also helps the human body to absorb and utilize nutrients.

③ Most nutrients will be lost when vegetables are left, because most vegetables are vitamins, and vitamins are afraid of heat, so they lose a lot after heating. Therefore, it is recommended not to leave food when eating. Leftovers can be reheated with fresh vegetables and "refurbished" into new dishes, which not only increases nutrition, but also improves taste.

7) It should be repackaged during storage to avoid repeated freezing and thawing and repeated heating. Meat, seafood, etc. It is best to cut into small pieces, repackage them and put them in the frozen layer, and take as much as you want to avoid repeated freezing and thawing, accelerating corruption or causing the destruction and loss of nutrients. Repeated heating of leftovers will cause greater nutritional loss. When nitrite is heated, its toxicity will be enhanced, even leading to food poisoning and even death. So don't heat a dish repeatedly.

8) Storage appliances should be selected. Try not to choose aluminum and stainless steel series, and it is best to choose porcelain plates or glass preservation boxes. Aluminum is easy to form alumina film in the air, and pickles or soup stored in it will have chemical changes and have adverse effects on the body. Wash the dishes you can't finish in advance and wrap them with plastic wrap to reduce the bacteria you carry.

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