Can frozen food in the refrigerator be stored for several years? Be aware of common misunderstandings when using refrigerators →

On this 315 Consumer Rights Day, many netizens posted photos of elderly people storing food from several years ago in the refrigerator with titles such as "315 should expose my grandmother (mother)", saying that it is still edible. Some big Vs even made jokes about this phenomenon, which became popular online. So is it appropriate to "store food in the refrigerator for several years"?

Let me first say the conclusion. These jokes can be taken as jokes. In life, we still need to use the refrigerator properly and not eat expired food. At the same time, we should also remind the elders at home and help them clean up the refrigerator regularly. Next, let's talk in detail about the common misunderstandings and precautions about using the refrigerator.

Put food in the refrigerator

Like entering a "safe"?

Many people, especially the elderly, are frugal by nature and always think that the refrigerator can freeze germs to death and that the remaining food is like a "safe" once it is in the refrigerator's cold storage compartment, and will not spoil for a long time. This is actually a common misunderstanding. The refrigerator's cold storage compartment is not a disinfection cabinet, let alone a safe.

The temperature of the refrigerator is usually around 4°C. On the one hand, germs are "afraid of heat but not cold", and low temperatures can only inhibit their reproduction speed, but cannot freeze them to death. As long as they return to room temperature, these germs will immediately multiply. On the other hand, some germs are more resistant to low temperatures and can quietly multiply even in the refrigerator, such as the famous Listeria. Therefore, do not treat the refrigerator as a safe, and the food stored in the refrigerator should be eaten or disposed of in time.

Put food in the freezer

Can it be stored indefinitely?

Because the freezer is mainly used to freeze meat, here we will take meat as an example. In theory, if meat is placed in the freezer and kept at a constant temperature, it can indeed be preserved for a long time, but it is not recommended to do so.

First of all, it should be emphasized that the freezer of a refrigerator cannot kill all bacteria. For example, Listeria mentioned earlier has a strong ability to withstand low temperatures and can survive in a freezer at -20°C for a year or even longer. It also likes to hide in animal foods such as meat - of course, frozen meat can still be eaten safely after being cooked.

The biggest problem with meat that has been frozen for too long is that the meat will become old, resulting in a poor taste. This is because compared to meat at room temperature, the rate of nutrient loss and deterioration is much lower after it is frozen. However, if it is stored for too long, the vitamin content of the meat will still decrease (such as vitamin B12, etc.), the protein and fat will gradually oxidize, and long-term freezing of the meat will also cause dehydration. Because of this, meat that has been frozen for too long will become woody and taste less fragrant when used for cooking.

Here we also want to remind everyone that when using the freezer, it is best to divide the food into small portions and freeze the appropriate amount at a time. Never thaw and freeze repeatedly, otherwise it will cause bacteria to multiply. In addition, summer is approaching, so don't put carbonated drinks directly into the freezer, otherwise it may explode.

Food in the refrigerator

Can it be placed anywhere?

When using the refrigerator, many friends often think that they will take out the food and eat it in a few days anyway, so they put the food randomly. In fact, this is not good for hygiene. The following are some basic principles that can help you use the refrigerator better.

First, separate the raw and cooked food. Generally speaking, cooked food and leftovers that are about to be eaten can be placed at the top of the refrigerator's refrigerated area, while raw food should be placed at the bottom. Secondly, different types of food, such as fruits, vegetables, meat and eggs, should be stored in separate areas. If conditions permit, you can use fresh-keeping bags and fresh-keeping boxes to separate various types of food and then store them. This will make it less likely to be contaminated and reduce water loss. In addition, because the refrigerator door is often opened and closed, the temperature fluctuates greatly, so it is not suitable to store eggs, opened milk and other foods.

Should leftovers be cooled before being put in the refrigerator?

Some friends are very conscious of energy conservation and environmental protection, and always think that putting hot dishes directly into the refrigerator will increase the energy consumption of the refrigerator. This may be true, but from a health point of view, the sooner leftovers are put into the refrigerator, the better.

This is because, as mentioned above, the main function of the refrigerator is to reduce the reproduction rate of bacteria through low temperature, so as to reduce the number of bacteria and allow food to be safely stored for a longer time. However, if we wait for hot dishes to cool down before putting them in the refrigerator, the bacteria will have more time to reproduce (the temperature range of 4℃~60℃ is conducive to the rapid reproduction of bacteria). And sometimes we will leave the dishes hanging there, and it will take a long time before we remember to put them in the refrigerator, which can easily lead to contamination.

Therefore, we should put the leftovers that we don't want to eat temporarily into the refrigerator as soon as possible to quickly put them into a low temperature state, so as to inhibit the reproduction of microorganisms. It is also very important to heat the leftovers in the refrigerator until they are cooked thoroughly before eating them.

Excerpted from the Dietary Guidelines for Chinese Residents 2022 Edition

Here we need to remind everyone that it is recommended to eat cold dishes all at once or dispose of the leftovers, and do not put them in the refrigerator. On the one hand, it is easier for bacteria to be mixed into cold dishes during the production process, and on the other hand, since it is a cold dish, we often do not heat it before eating.

The refrigerator can inhibit bacteria

No need to clean up and scrub frequently?

This is not the case. Refrigerators also need to be defrosted, de-iced, cleaned and disinfected regularly. On the one hand, the low temperature of the refrigerator can only inhibit the growth of bacteria. If it is not cleaned and disinfected for a long time, it may still cause bacteria to grow and contaminate food. On the other hand, frost and ice may still accumulate in the refrigerator after a long time of use, which may reduce the refrigerator's cooling effect. In addition, due to the narrow field of view in the refrigerator, the stored items often block each other, which may cause us to forget some food in the refrigerator for too long, so that it becomes a breeding ground for bacteria.

Therefore, we should not forget to clean the refrigerator regularly. If conditions permit, it is best to clean it once a month.

Fruit Love

Is it better to store it in the refrigerator?

This cannot be generalized. Tropical fruits such as mangoes and bananas should not be kept in the refrigerator for a long time (such as more than a week or more), which may cause them to be frostbitten, the skin will turn black, and affect their edible value. However, it is okay to store them for a short period of time, keep them fresh, or chill them before eating. rId8 copyrighted image, unauthorized reproduction In addition, we should also pay attention that some fruits and vegetables will produce ethylene (such as bananas), which may ripen other fruits and vegetables stored together, so they should be stored separately.

Can medicines be kept longer in the refrigerator?

Some friends look at medicines in the same way as food, thinking that since the refrigerator can keep food fresh, then medicines must be able to last longer if stored in the refrigerator. This view is not comprehensive enough, and we should store them according to the drug instructions.

Here is a basic judgment standard for everyone. According to the "Chinese Pharmacopoeia", a cool place means no more than 20℃, a cold place means 2℃~10℃, a cool dark place means no more than 20℃ away from light, and room temperature means 10℃~30℃. The instructions for drugs often contain words like "store at XX place", just refer to the regulations of the pharmacopoeia. If there is no special instruction in the instructions, it is usually stored at room temperature.

It is important to note that children's antipyretic drugs are often suspensions and do not need to be refrigerated, otherwise they may cause precipitation and affect accurate medication.

Finally, to sum up, the refrigerator is not a disinfection cabinet, nor a safe. We should regard it as a temporary storage box for food. No food should be kept in the refrigerator for too long. Considering that it is quite convenient for us to buy vegetables and meat now, there is no need to store several months of ingredients in the refrigerator. When we cook, it is also best to calculate the daily amount of family members and sell as much as they eat, so as to avoid waste and eat fresh ingredients. If there are leftovers in the refrigerator occasionally, remember to heat them thoroughly before eating.

Planning and production

Author: Ding Zong

Comprehensive from Popular Science China Science Rumors

Review｜Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center

Editor: Ding Zong

Proofread by Xu Lailinlin