If there are leftovers in the morning and I eat them at night, is it okay as long as they are not left overnight?

Review expert: Wang Guoyi, Postdoctoral Fellow in Nutrition and Food Safety, China Agricultural University

Whether you cook at home or eat out, it is inevitable that there will be leftovers. If you want to finish your meal, your stomach will feel uncomfortable. If you pack it up and eat it the next day, you may worry that it is unhealthy. People have always been arguing about whether overnight food is safe. Can we eat overnight food?

Which foods can be left for the next day? How to store leftover food? Let’s find out today~

Source: pixabay

1Can I eat overnight food?

Generally speaking, all overnight food is collectively referred to as overnight rice or overnight dishes, but from a scientific point of view, no matter whether it is left overnight or left from morning to night, only food that has been left for more than 8-10 hours is considered overnight dishes.

Whether overnight food can be eaten does not depend on whether it is refrigerated or how long it is stored, but on whether it deteriorates or produces harmful substances during the storage process.

That is to say, there are two main safety hazards of overnight food: one is the proliferation of microorganisms , which causes food to spoil; the other is the increase in nitrite content during storage, which may lead to poisoning and the risk of cancer. The air is full of microorganisms, and food exposed to the air will inevitably be used as a breeding ground by them. If left at room temperature for a long time, the microorganisms have a suitable environment and temperature, and the reproduction rate is fast, and the food is easy to spoil. However, as long as the unfinished food is put in the refrigerator in time, the growth of bacteria can be inhibited and the rate of spoilage can be greatly slowed down.

Source: pixabay

Many people are more worried about the increase in nitrite content in food when it is left out for a long time, which is not good for health. However, nitrite itself is not carcinogenic. It will react with protein decomposition products to produce carcinogenic nitrosamines. Long-term and large-scale consumption will cause cancer risks.

However, food hazards cannot be discussed without considering the dosage. Nitrite is widely present in various natural substances. In fact, only a large amount of nitrite in a short period of time will cause acute poisoning, dizziness and vomiting, and in severe cases, coma or even death. Whether it is meat, eggs or vegetables, the average nitrite content is 3-5 mg/kg.

The Chinese Journal of Preventive Medicine states that the lowest toxic dose of oral nitrite for adults is about 300mg-500mg, and ingestion of 1-3g will lead to death. However, the nitrite content of overnight meals (excluding pickled foods) that have been refrigerated for up to 24 hours will not exceed 10mg/kg, which is far from the toxic dose. As long as they are not spoiled, it is okay to eat overnight meals occasionally.

In addition, nitrite is also an internationally recognized food preservative. If it is added within the standard range, it will not cause harm to the body.

Source: Baidu

However, it should be noted that during major festivals such as the Spring Festival, some families eat the same dish for many days. The above instructions for overnight dishes are not applicable. The harm of overnight dishes can only be ignored if they are stored properly and the storage time should not be too long.

2. Scientific storage of overnight vegetables

It is sometimes difficult to tell whether leftover food has gone bad by sight or taste, and it is even more difficult to tell how much nitrite it contains. So how do we ensure the safety of leftover food? The key lies in storage. If it is not stored properly, it may go bad in a short period of time.

The second consumption of overnight dishes depends on the following three aspects:

1. Storage time :

It is recommended that leftovers should not be stored for more than 4 hours at room temperature, and no more than 2 hours in hot weather. The longer they are stored, the easier it is to spoil. Since microorganisms have a strong reproductive capacity at 20-30℃, letting food cool completely before refrigerating it will breed more bacteria. As long as leftovers are left to some residual temperature, they can be put into the refrigerator.

2. Storage method :

If you cook a lot of food, it is best to put it in a fresh-keeping box before eating. If you store it after eating, a lot of bacteria will enter the food. It is best to put it in a clean fresh-keeping box or cover it with plastic wrap to separate it from other foods to prevent odor contamination. Secondly, raw and cooked food need to be strictly separated to avoid parasites in raw food and cross infection. The refrigeration temperature should be 2-8℃, and some foods can be frozen.

Source: pexels

3. Secondary consumption method :

When eating overnight dishes for the second time, they must be heated thoroughly. Soups need to be heated and boiled for more than 3 minutes, and meats need to be heated and boiled for 10 minutes to kill bacteria. As for some cold dishes and stewed food, it is not recommended to leave them "overnight". Try to finish them in one meal. If you can't finish them but can't bear to throw them away, although the taste will be greatly reduced, you still have to heat them until they are cooked before eating. In general, as long as the food is stored properly, it will not deteriorate, and the nitrite produced will have a very small probability of causing poisoning. Overnight meals can be eaten, but the taste of overnight meals is not as good as fresh food, and the nutritional value is also lost a lot, so it is recommended to eat them now, and it is not recommended to eat overnight dishes frequently.

3Which foods are not recommended to be stored overnight?

The refrigerator can protect overnight food from spoiling, but not all food is safe, and some food is not suitable for overnight storage. Let's take a look at which ones are:

1. Green leafy vegetables

There is an old saying: "It is better to have leftover meat than vegetables". Compared with fruits, meat and eggs, green leafy vegetables have a higher nitrate content. If left out after cooking, they will produce more nitrite, which is not good for health. In addition, the taste of overnight vegetables becomes worse after reheating. Beans and tubers can be stored appropriately, but not for more than 8 hours.

Source: pexels

2. Soups

After a long period of stewing, the soup is rich in nutrients. At room temperature, it can be said to be a "hothouse" for bacteria, which can easily breed a large number of bacteria. If the leftover soup is placed in a stainless steel or aluminum pot, it is easy to react and cause harmful substances to precipitate. It is recommended to separately serve the amount of soup to be drunk that day, and place the rest in a glass or ceramic container and refrigerate or freeze it.

3. Seafood and cold dishes

Seafood is rich in protein, which is easily decomposed by microorganisms overnight, damaging the liver and kidneys of the human body. If it is pickled, you can eat part of it as needed and reduce the amount of stirring with chopsticks.

4. Soft-boiled eggs

More and more people like to eat sterile "soft-boiled eggs", but these half-cooked eggs are not really sterile. In addition, they are rich in nutrients and are prone to infection by various bacteria, which can cause gastrointestinal discomfort and other symptoms after consumption. If they are fully cooked eggs, they can be stored at low temperatures.

Source: pexels

After reading this, I believe you have a deeper understanding of food storage. The weather is hot and food is easy to spoil. Everyone should pay more attention to food safety. Food that cannot be finished should be put in the refrigerator as soon as possible and eaten as soon as possible.