After the food safety storm, "self-cooking management" has become a diet mode for many families to avoid black-hearted food, but most of the leftovers that can't be eaten have become dishes heated by their elders the next day, and they have also become invisible killers that erode their health. But do all the leftovers really have to be thrown away? In fact, as long as you master the correct preservation method, overnight leftovers can still be safely eaten.
In the days of economic depression, it is always difficult to decide whether to throw away the leftovers overnight or stay to eat. Huang Shuhui, a nutritionist at Taibei Post Hospital, said that the leftovers were discarded because she was worried that overnight dishes would produce a large amount of carcinogen "nitrite", but this was only limited to leafy vegetables such as Chinese cabbage, Qingjiang vegetables, spinach and spinach, and there was no problem with roots such as potatoes. As for meat and seafood, improper preservation often leads to bacterial growth and food poisoning, thus affecting health.
Leftovers are easy to release nitrite, and eating more will cause cancer.
Studies have found that "nitrite" is one of the carcinogens that cause intestinal cancer, liver cancer, gastric cancer and esophageal cancer. Nitrite meets stale amine foods, such as stale mussels or squid, which will form "nitrosamines", which is the chief culprit of gastric cancer; If hot dogs and barbecue flowers are eaten together, or many vegetables are eaten together with barbecue flowers, it will increase the formation of carcinogen nitrite and increase the risk of cancer.
Generally speaking, dishes left for more than 6 hours can be called "leftovers". Huang Shuhui pointed out that not all leftovers can be eaten. You can have dinner if you haven't finished eating Chinese food, or you can have breakfast the next day from dinner the day before. But these overnight dishes should pay special attention to the storage time and whether they are properly preserved.
Leafy vegetables are easy to release a lot of nitrite after being cooked for a long time, even organic leafy vegetables are inevitable, mainly because leafy vegetables can not be separated from nitrogen fertilizer after fertilization, and then nitrate will be produced in vegetables. If left for a long time, nitrite will be released naturally, which will also be harmful to health.
Six methods of food selection and leftovers preservation
In order to reduce the nitrate content in leafy vegetables and other ingredients, Huang Shuhui suggested that we can increase the nitrate content by buying ingredients and storing them after cooking.
"Method 1" is the first choice for seasonal leafy vegetables.
Regarding the choice of ingredients, Huang Shuhui suggested that leafy vegetables should be based on the principle of "at that time of the season" and abundant sunshine. If there is enough sunshine, the nitrate content of leafy vegetables will be reduced, and less nitrite will be produced after cooking. For example, before and after rainy days or typhoons, the nitrate residue in vegetables grabbed by farmers is definitely high, so it is best to avoid buying them and buy root foods instead.
"Method 2" Leftovers are completely sealed and refrigerated.
The preservation time of leftovers must not be too long, otherwise more bacteria will easily breed and accelerate the release of nitrite, leading to the continuous increase of nitrite in leftovers; It is also important to keep the leftovers completely sealed, but some mothers feel that the next meal is about to be eaten, and the leftovers at noon simply stay on the table without refrigeration. Unexpectedly, after 3 or 4 hours, the leftovers will go bad and release a lot of nitrite, and the higher the temperature, the faster the bacteria multiply, which is harmful to the health.
"Method 3" Don't heat overnight dishes repeatedly.
Braised Chinese cabbage and shredded bamboo shoots are not only famous snacks in Taiwan Province Province, but also standing dishes on many family tables, especially Chinese cabbage, which is a good entrance to soften after pickling. However, from the perspective of food safety, Huang Shuhui said, "The curing time is too long." As a result of repeated heating, not only all nutrients are exhausted, but also nitrite is released and more harmful chemicals are decomposed. Like shredded bamboo shoots and dried bamboo shoots, it will be smoked by sulfur dioxide. It is difficult to remove sulfur dioxide before eating. Repeated heating will only release more sulfur dioxide. So these two leftovers are heated once every other day at most. Don't eat after eating.
Another worry is that many mothers-in-law have the habit of "adding new dishes to old dishes" before cooking, which is equivalent to transferring all the harmful substances at the bottom of old dishes to new dishes. If heated repeatedly, more harmful chemicals will be released. In summer, appetizing cold salad, such as cold cucumber, although there is no nitrite problem, it is easy to breed bacteria. It is best not to eat overnight. If you want to eat every other meal, you must also refrigerate it.
"Method 4" Bean products were frozen and blanched before eating.
Bean foods such as tofu and dried beans are also common ingredients on the family table, and they are also easy to rot and sour. Huang Shuhui said that preservatives would be added to most bean products in the market to delay the deterioration of bean products. It is suggested that the first thing to do after purchasing this kind of bean products is to soak them in water and blanch them with hot water, which can reduce the residue of hydrogen peroxide, but the relative time limit for safe consumption will also be shortened. Therefore, raw tofu without any additives is best frozen, not refrigerated, otherwise the shelf life is extremely short and it is easy to rot.
"Method 5" leftover meat and seafood should be frozen and preserved.
The food safety doubt of meat and seafood lies in the growth of bacteria, such as botulinum toxin and some microorganisms. Many families like to pickle a large pot of meat. In the process of marinating meat, high salinity soy sauce and some spices will be added. These all have the effect of inhibiting the growth of bacteria, which is equivalent to prolonging the eating time, but it does not mean that bacteria will not breed after repeated heating. Unless you eat it every other meal, it is recommended to keep it frozen. Seafood food, if you continue to eat within 4 hours, can be stored in cold storage first, but if there are shellfish in the dish, it is best to keep it in cold storage.
"Method 6" Starch foods can be stored in cold storage.
Starchy foods, such as potatoes, can't be stored for more than 4 hours if they have been seasoned or mashed, such as mashed potatoes or salads, but they can be stored in cold storage if they are boiled potato pieces.
No leftovers, cook as much as you eat!
Old people in many families often regard overnight dishes as the only dishes on the table, which makes their families worry about eating nitrite, a carcinogen. In fact, "cook as much as you eat!" Huang Shuhui believes that this is the simplest way to prevent the elderly from eating leftovers.
However, in today's society, the family population is generally thin, cooking more and eating less, and eating overnight dishes is no longer just a problem for the elderly. Many families may eat leftovers for days on end. Huang Shuhui said that instead of trying to change the old people's habit of eating leftovers, it is better to improve the problem of eating leftovers through faster and simpler cooking mode, so as to obtain enough nutrition and maintain food safety.
Three Tips for Eating Leftovers Healthy
● Beef turns into a new dish.
You can buy more tenderloin and brisket to go home, boil them in water first, and then bag them according to the number of people eating at home and put them in the refrigerator for freezing. When you want to eat, take out a bag, then mix with various seasonings and cook different dishes. Maybe adding carrots today will turn into "braised beef brisket", and adding potatoes and curry tomorrow will turn into "curry beef". Because beef is cooked first, cooking time can also be shortened when other leafy vegetables or roots are added. Otherwise, eating a pot of beef tendon or brisket for a week may soon lead to loss of appetite, affecting the nutritional absorption of the elderly.
● Braised pork is packaged and frozen, thawed and heated before eating.
Or a pot of braised pork or stewed vegetables, which can't be cooled after eating, can be packaged in sealed bags, frozen according to the consumption of each meal, and only one bag can be taken out and thawed at a time, so as to avoid nutritional loss caused by heating the same pot of vegetables every day.
● Rice turns into fried rice or risotto.
Rice can be cooked in the same way. Two cups of rice can be cooked into four bowls of rice, which is enough for the couple to eat for two days. The uncooked rice on the first day is cooled and frozen in the refrigerator. Steamed in a rice cooker when eating, or used for fried rice. You can also cook frozen beef tendon and vegetables together in Luo Songtang, and pour them on hot rice, which will become "Luo Songtang risotto".
Frozen food is effectively sterilized by boiling and heating.
Packaging and freezing can prolong the shelf life of food, but it does not mean permanent preservation. She pointed out that frozen meat can generally be kept for one month, and it must be boiled when it is taken out, thawed and heated, because bacteria such as botulinum toxin must be boiled to effectively sterilize. However, some people think that it can be eaten with a little heating. In fact, the bacteria in these meats have not been completely eliminated, and eating them is likely to cause bacterial food poisoning.