Whether cooking at home or packing in a restaurant, leftovers are inevitable. Reheat the next day, not only the taste may be greatly reduced, but also people will have doubts about safety and nutrition.
A dish, after a night of shelving, what has changed?
Overnight meals have two major safety hazards
Overnight meals mainly refer to overnight vegetables, overnight meat, overnight tremella soup, etc. some people think that overnight meals are even after a night, while others think that more than 8 hours are enough regardless of day or night.
In fact, the safety of leftovers is not whether they are stored overnight or for a long time, but whether they produce harmful substances or deteriorate during storage.
In the safety assessment of overnight dishes, the biggest focus of debate is whether it causes cancer and poisoning. Overnight food usually has two major safety problems:
First, microbial reproduction will lead to food deterioration;
Second, the increase of nitrite can cause food poisoning and cancer risk.
What is nitrite?
Many preconditions are needed to convert nitrite into nitrosamine carcinogens. Nitrite is very common in fruits and vegetables, almost all of them.
Nitrite is also found in many processed meat, such as pink sauce beef, boiled meat slices, Hangzhou pepper beef fillet, etc. In contrast, there is no need to worry about nitrite in leftovers.
Is nitrite in overnight food growing fast?
The experiment shows that if the spinach is not turned after cooking, it is refrigerated at 4 ℃ in the refrigerator. After 24 hours, the nitrite content of green leafy vegetables such as spinach increases from 3 mg / kg to 7 mg / kg. To reach the poisoning level, eat at least dozens of kilograms of overnight vegetables. Therefore, eating half a catty of spinach every day does not need to worry about cancer.
Auricularia auricula does contain more nitrate, but that is the amount in dry products. After soaking, the nitrate content has become 1 / 10, which is far lower than that in many leafy vegetables.
What is the nitrite content of overnight tea?
Tea is a kind of leaves with high nitrate content, but only 1 ~ 2 grams of tea are put into a cup of tea normally. The total amount of nitrate is about 6 mg. Even if it all turns into nitrite, it will not cause poisoning. The saying that overnight water is toxic is pure rumor and has no basis.
It should be reminded that the food safety risk of overnight food is indeed greater than that of freshly cooked food.
Whether you can eat overnight food depends on one condition
Whether overnight food can be eaten depends on the storage conditions. For example, leftovers, soup, cold dishes and stewed dishes at room temperature overnight are best not to eat, because they are easy to exceed the standard of bacteria and cause diarrhea and other diseases.
The general recommendation of the scientific community is that the leftovers should be stored at room temperature for no more than 4 hours and no more than 2 hours when the temperature is high.
According to the actual situation in our life, when there is residual heat in the leftovers, they are boxed and put into the refrigerator. Although it costs a little more electricity, it is safer.
This is because bacteria reproduce fastest at 20 ℃ ~ 30 ℃, so it is necessary to cool down to cold storage conditions as soon as possible. In addition, leftovers need to be thoroughly hot when they are eaten again, and they should not be stored in the refrigerator for too long.
For cold vegetables, it is recommended to do as much as you eat, and the rest needs to be thrown away to avoid food safety risks. If it is stewed cold dishes or meat dishes, such as soy sauce beef, it is safe to steam in a pot before eating.
5 kinds of food are not recommended to be stored overnight
Not all leftovers have no safety risk. The following types of food are best not to be placed overnight.
Soup
If the remaining soup is placed in aluminum and stainless steel pots for a long time, it is easy to produce chemical reaction and precipitate harmful substances.
It is recommended not to put condiments such as salt at the bottom of the soup. Scoop out the cooked soup with a clean spoon. If you can’t finish drinking, you’d better put it in glass or ceramic containers and store it in the refrigerator.
Fish and seafood
Fish and seafood are prone to protein degradation overnight, which may damage liver and kidney functions.
Bulk brine
Bulk brine should be eaten on the same day, not overnight. From the perspective of food safety, this is unsanitary. Even in the refrigerator, it is not absolutely safe. Mold and psychrophilic bacteria are also easy to breed in the refrigerator.
Tremella fuciformis
Both Tremella cultivated indoors and Tremella cultivated in the field with basswood contain more nitrate. If it is cooked and placed for too long, the nitrate will be reduced to nitrite under the decomposition of bacteria.
Egg
If the egg is not fully cooked, the immature egg yolk can be eaten overnight. If it is not properly preserved, it is easy to breed bacteria due to its rich nutrients, resulting in gastrointestinal discomfort, flatulence, etc.
But if the eggs are well cooked and sealed at low temperature, there is generally no problem. ▲
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