It can’t be said that the health of overnight dishes is closely related to storage conditions, food materials and cooking methods. Many people worry that overnight food is unhealthy because they hear that “overnight food can cause cancer” – overnight food will produce a lot of nitrite, which will produce nitrosamines when it enters the body. The basis of nitrite production is that bacteria propagate in meals. Therefore, in order to ensure the safety of overnight dishes, it is necessary to inhibit the growth of bacteria. < / P > < p > first of all, it depends on the temperature. If the overnight dishes are stored at room temperature of about 10 ℃ or 20 ℃, bacteria will proliferate rapidly, which will easily lead to spoilage of dishes, produce more pathogenic bacteria or bacterial toxins, and may also greatly increase the content of nitrite. < / P > < p > however, if the overnight dishes are stored in the environment below 10 ℃, it is safe to put them all night. Although the number of bacteria and nitrite content will increase, but usually will not reach the actual harm value. < / P > < p > secondly, it depends on the ingredients. Vegetables should not be overnight. From the safety point of view, vegetables are the most likely to produce nitrite. Because vegetables contain a substance called nitrate, which is harmless and even good for the cardiovascular system. But under the action of bacteria, nitrate in vegetables will become nitrite, which is the carcinogen we are worried about. < / P > < p > aquatic products should not be overnight. Generally speaking, meat dishes are OK overnight. When heated again, some B vitamins are lost, but the protein and minerals can be completely retained, and the taste does not change significantly. But aquatic products are an exception. Because the protein in aquatic products is particularly vulnerable to microbial decomposition. Studies have shown that shrimp, crab, shellfish and other aquatic products are often contaminated by low-temperature resistant microorganisms, and these foods are usually cooked for the sake of freshness and delicacy, and the heating time is short. If they are not thoroughly heated, they can not kill all the microorganisms. Even if they are refrigerated in the refrigerator, there is also a risk of pathogenic microorganisms breeding. The staple food should be frozen for a long time. If there is rice left, and the next meal can not be finished, can be divided into small portions into cold storage. If there are cakes, steamed buns, steamed buns, dumplings and other easy to dry, hard pasta, should be divided into one can eat the amount, into a fresh-keeping bag or lunch box. One of them should be eaten the next day in the freezer, and the others should be frozen in the freezer. When necessary, they can be taken out and steamed, or directly used in the “thawing” file of the microwave oven. < / P > < p > Third, it depends on the cooking method. Raw cold dishes, such as shredded cabbage and mixed turnip, have not been heated and sterilized, and the nitrate in them has not been removed. The “basic” of such ingredients is not good, and it is more likely to cause bacterial breeding. And the next time the salad is heated, the taste will be strange, so don’t make it overnight. < / P > < p > meat salad is not recommended overnight, because even if it can be kept refrigerated, bacteria will grow. If you are greedy for taste, it is not safe to continue to eat “cold” next meal. Of course, I have no objection to eating cold dishes for the first meal and heating them thoroughly for the second. < / P > < p > Fourth, leftovers should be left first. When the food is just out of the pot, there are few bacteria. Because the process of cooking and heating is a process of high temperature sterilization. However, if you eat it on the table for a while, you are pushed around with chopsticks, and your saliva is mixed with it, which is equivalent to helping the bacteria “inoculate”. Therefore, if the food is ordered or cooked too much, it is better to set aside some of them first, and then eat the rest together, so as to minimize the contact between the food and bacteria. Fifthly, refrigeration must be carried out as soon as possible. If the vegetables are cooked without turning, put them into a clean fresh-keeping box immediately, and put them in the refrigerator when they are not hot, so the safety is higher. Every time I make such a suggestion, someone will say, “put the food in the refrigerator when the food is still warm. How bad the refrigerator is!” I especially want to ask: is the health of oneself important, or the health of refrigerator important? And do you really have such a used refrigerator in your home?