Many families are troubled by leftovers from every meal. Can overnight food still be eaten? It is rumored that 8 types of food should not be left overnight, as eating them might lead to food poisoning and even increase the risk of cancer. Which overnight foods should not be eaten? How can leftovers be handled without waste?
“Overnight food” doesn't just refer to food left for one night. If the food has been out for more than 8-10 hours, it should be considered overnight. There are two reasons for the increase in toxic components in food. First, chemical substances in the food produce carcinogens, such as nitrites, which cannot be removed even by reheating. The second reason is secondary contamination from external bacteria during storage. Generally, stem and leafy vegetables have the highest nitrate content, followed by root and stem vegetables and cauliflower-type vegetables, with gourd vegetables being the lowest. Seafood such as crabs, fish, and shrimp, when left overnight, will produce protein degradation products that can damage liver and kidney function.
The following foods are particularly harmful when stored for a long time:
1. Leftover green leafy vegetables are the most dangerous.
Generally, stem and leafy vegetables have the highest nitrate content, followed by root and stem vegetables and cauliflower-type vegetables, with gourd vegetables being the lowest. Therefore, if you buy a large amount of vegetables, you should eat leafy vegetables first, such as Chinese cabbage and spinach. If you plan to cook extra food to reheat the next day, you should try to make less of the stem and leafy vegetables and choose gourd vegetables instead.
2. Leftover seafood damages the liver and kidneys.
Seafood such as crabs, fish, and shrimp will produce protein degradation products when left overnight, which can damage liver and kidney function. If you have bought too much, you can pack the raw seafood in a fresh-keeping bag or container and freeze it in the refrigerator to cook later.
3. Semi-cooked eggs can easily cause illness.
Many people love soft, semi-cooked eggs with runny yolks. However, these eggs are not thoroughly sterilized. Coupled with the fact that eggs are rich in nutrients, they are particularly prone to bacterial growth, which can be dangerous after consumption. If the eggs are fully cooked and stored properly in a sealed, low-temperature environment, it is fine to eat them the next day.
4. Be careful with silver ear fungus and mushrooms.
Whether wild or cultivated, silver ear fungus and mushrooms can easily retain a lot of nitrates. If they have been stored for a long time, you may have to discard them.
5. Do not store soup in metal containers.
Boiling soup is time-consuming and labor-intensive, so people often make a large pot that lasts for several days. If leftover soup is stored in an aluminum or iron pot for a long time, harmful substances to the human body may be leached out. The best way to store soup is to not add salt or other seasonings. After cooking, use a clean spoon to scoop out the portion to be consumed that day. Any leftover soup should be stored in a clay pot or a fresh-keeping container in the refrigerator.
6. Home-braised food should not be left overnight.
In spring and summer, braised food should not be left overnight. Bulk braised food should be finished on the same day and not left overnight. Food experts remind that even food stored in the refrigerator is not absolutely "safe." Molds and psychrophilic bacteria can easily grow in the refrigerator. If possible, it is best not to eat overnight braised food.
7. Leftover salad can cause food poisoning.
Cold dishes made with various vegetables, dried fruits, and vinegar, when stored in the refrigerator overnight, are prone to growing mold, which can cause food poisoning if eaten.
8. Never drink overnight tea.
Due to the long time, most vitamins in overnight tea have been lost. Moreover, proteins and sugars in the tea become nutrients for the breeding of bacteria and mold. Therefore, people generally believe that overnight tea should not be drunk.
How to handle leftovers without waste?
1. It's better to have leftover meat dishes than leftover vegetable dishes.
Meat dishes stored in the refrigerator can be kept for 1-2 days as long as they are thoroughly reheated before consumption. Although some B vitamins are lost, the protein is completely retained, and no harmful substances are produced. In contrast, vegetables can easily produce nitrites during storage, and their antioxidant components, vitamin C, folic acid, etc., are severely lost during storage and reheating.
On the other hand, leftover meat dishes still taste good when reheated, while reheated vegetables almost lose their culinary value. Therefore, during a meal, you should focus on finishing all the vegetables, while the meat dishes can be saved for the next meal.
Among the meat dishes, aquatic products should be finished first, as they can be stored for a shorter time than meat. This is because the protein in aquatic products is particularly easily decomposed by microorganisms, and they are also more prone to harmful microbial growth.
2. It's best to store leftover food in glass containers.
Leftover food is not a scourge; there's no need to be afraid of it as long as it is not stored for too long or consumed too frequently. The harm of nitrates and nitrites in food to the human body is minimal.
Of course, to minimize the impact of harmful substances on the body, it is best to store leftover cooked food in sealed, categorized glass or ceramic containers when refrigerating. When consuming food from the refrigerator again, it must be thoroughly heated to a high temperature. Fresh raw meat is best eaten as soon as it is bought. If it cannot be used up at once, it is best to freeze it in the refrigerator, which is the best way to preserve it.
It should be noted that the leftovers mentioned above do not include cooked freshwater and seafood, or cold dishes. Cooked freshwater and seafood, when stored for a long time, can easily produce protein degradation products that can damage liver and kidney function and even produce toxins. Cold dishes, on the other hand, are more susceptible to contamination and can spoil easily even when refrigerated.
3. Portion in advance.
If you know you won't finish a meal, you should portion it into different plates as soon as it's cooked. Once one portion has cooled down a bit, put it in the refrigerator. This way, the "base number" of bacteria in the food is very low, and it will be fine to eat it thoroughly heated the next day or even the day after. If the food has been sitting out for two or three hours and you have stirred it around with chopsticks, its shelf life will be shortened. In this case, spread it out a bit, place it in the innermost part of the lower shelf of the refrigerator, and let it cool down to the refrigerator's temperature as quickly as possible.
4. Thoroughly reheat.
It's okay to save leftovers for the next meal, but they must be thoroughly reheated. Thorough reheating means heating the entire dish to 100°C and keeping it boiling for more than 3 minutes. Using a microwave to reheat leftovers is a good method, as it can heat the inside of the food thoroughly.
However, at home, it's often difficult to control the microwave heating time, and food can easily splatter inside the microwave. You can consider heating the food in the microwave for one or two minutes first to raise its internal temperature, and then finish heating it in a pot or by steaming it, which makes it easier to heat through. For leftover dishes that you don't want to be too soupy, you can use steaming or pan-frying to reheat them.
It is highly important to note that food should not be reheated multiple times. If you know you won't finish the fish or meat for the second meal, only heat half and put the remaining portion back in the deep part of the refrigerator. Some cooked foods and bean products can even be divided into small portions and frozen directly in the freezer.