Should overnight food be eaten or thrown away? Can expired food still be eaten if it has not changed its taste? Pay attention to these points when storing food!

In the hot summer, the temptation of delicious food is everywhere. After enjoying delicious food, are you often troubled by the same question: should you eat the leftover food or throw it away? Do you always wonder whether you can still eat expired food if it has not changed its taste?

In fact, there are many things to pay attention to when preserving food. We invited Ma Xiaochen, deputy director and chief physician of the Nutrition and Food Hygiene Institute of Beijing Center for Disease Control and Prevention, to explain to everyone how to properly handle overnight dishes and expired foods, so that we no longer have to worry about shelf life and taste changes, and avoid the risk of food poisoning.

1

Store unfinished food in the refrigerator

Will it breed bacteria?

The main principle of refrigerators to preserve food is to lower the temperature. Generally, the most suitable temperature for bacteria to grow and reproduce is 37°C. Refrigerators can inhibit the growth and reproduction of bacteria by lowering the temperature, but they cannot kill bacteria.

In particular, there are some bacteria that like cold, which are often called psychrophilic bacteria, such as Listeria monocytogenes and Yersinia enterocolitica, which can continue to grow and reproduce at low temperatures .

The refrigerator is not a safe. Food put in the refrigerator should be eaten as soon as possible. Food taken out of the refrigerator should be thoroughly heated, cooked and cooked before eating.

2

Can I eat overnight food?

Whether overnight food can be eaten mainly depends on two aspects:

On the one hand, there is chemical food poisoning. Many netizens say that overnight food can cause nitrite poisoning. In fact, nitrates and nitrites are nitrogen-containing chemicals that are widely present in the environment. Some vegetables, especially wild vegetables, also contain them. Under the action of bacteria, nitrates will be reduced to nitrites. As time goes by, the nitrite content will increase.

We once did an experiment like this: we put cooked meat dishes, leafy vegetables (such as rapeseed), and root vegetables (such as eggplant and broccoli) in the refrigerator for 48 hours, and then tested their nitrite content. The result showed that no nitrite content was detected in meat dishes, while the nitrite content in vegetables increased, with the largest increase in leafy vegetables. Although the root vegetables also increased, the increase was not as much as that of leafy vegetables, and none of them reached the dose that could cause poisoning, so it would not cause nitrite poisoning.

On the other hand, there is bacterial food poisoning. Overnight dishes are contaminated by bacteria and then stored in the refrigerator. The refrigerator can only inhibit the growth and reproduction of bacteria, but cannot completely kill the bacteria. Some bacteria that are not afraid of cold continue to grow and reproduce in the refrigerator. When they reach a certain number, bacterial food poisoning will easily occur.

In general, although overnight food can be eaten, the shorter the interval, the better, and at most one meal. In addition, considering that bacteria may multiply, it is still necessary to heat it thoroughly before eating to kill the bacteria.

What we need to emphasize here is that we should try to eat and cook as much as possible , whether we are dining out or cooking at home, and we must eat in moderation to avoid leftovers.

3

If food is expired but has not changed its taste, can it still be eaten?

The shelf life of food refers to the time range within which the food can be eaten safely and maintain its quality under the storage conditions specified on the label.

Can we eat expired food? This question cannot be generalized.

Foods with a particularly short shelf life, such as fresh milk, fresh meat, pre-packaged refrigerated foods, etc., should be used strictly within the shelf life.

Foods with a particularly long shelf life , such as potato chips, can still be eaten one or two days after the expiration date if the outer packaging is intact and not damaged, and there is no obvious mold or odor after opening. The taste of the food may be poor at this time, but there is no problem from a safety perspective.

When it comes to shelf life, you should pay special attention to the storage conditions. For example, pasteurized milk that we often drink usually needs to be refrigerated so that it can be stored for 2 to 3 days. However, if it is placed directly at room temperature after purchase, or even exposed to the sun, it will go bad in less than 2 to 3 days. Another example is oyster sauce, which needs to be refrigerated immediately after opening. If it is still used at room temperature after opening, it may go bad before the shelf life. Therefore, we should not only pay attention to the shelf life, but also the storage conditions of food.

In short, we should buy food in moderation, store food under prescribed storage conditions, consume it as soon as possible within the shelf life, and eliminate food waste.