Beware! Bacteria "Killers" in the Refrigerator

In the long history of biological evolution

We humans are just a "latecomer"

Microorganisms billions of years ago

It has quietly taken over the earth.

They are so small that they cannot be seen with the naked eye.

But it is an "enemy" of human health that cannot be ignored

(Copyrighted image from the gallery, no permission to reprint)

A large part of foodborne diseases are caused by these tiny microorganisms that contaminate food. The following are some of the most powerful "excellent" representatives of microorganisms.

The refrigerator itself does not have a sterilization function. Its low temperature environment inhibits the growth and reproduction rate of most microorganisms and inhibits the action of enzymes to delay the spoilage of food. However, psychrophilic bacteria can still reproduce and cause the spoilage of refrigerated food.

Psychrophile is a general term for a type of bacteria. This type of bacteria generally grows best between -15 and 20°C. Because this temperature range is much colder than the temperature range that other bacteria grow best (the suitable growth temperature for ordinary bacteria is 25 to 40°C), they are named psychrophile.

The most common psychrophilic species are Yersinia and Listeria.

Listeria is a facultative anaerobic Gram-positive rod, of which Listeria monocytogenes is the most important species. This bacterium can survive in a variety of different environmental conditions. It can continue to grow and reproduce at 4°C in the refrigerator, grow slowly at 0°C, and even survive for up to 1 year at -20°C.

(Copyrighted image from the gallery, no permission to reprint)

Listeria is more deadly than most common bacteria, so it is called the "refrigerator killer."

The main type of Yersinia is Yersinia enterocolitica, which can survive and reproduce in the refrigerator. The enteritis it causes is called "refrigerator enteritis."

In addition to psychrophilic bacteria, many bacteria reproduce more slowly below -10°C and stop reproducing at about -15°C in the freezer. However, this does not mean that the bacteria are dead. Once they return to room temperature, the bacteria will still reproduce in large numbers, causing the risk of food poisoning.

Other hardy bacteria in the refrigerator that can cause food poisoning include Pseudomonas, Escherichia coli, Salmonella, Shigella and some molds.

These pathogens are mainly found in dairy products, milk and some meats, especially beef, ice cream, salads and vegetables. The results of food safety risk monitoring in my country in recent years show that Listeria monocytogenes has the highest contamination rate in raw meat and ready-to-eat foods.

If you eat food contaminated by these bacteria, you may experience abdominal pain, diarrhea, fever and other intestinal diseases, or even sepsis and central nervous system infection. This mainly happens to pregnant women, fetuses, newborns, people with weakened immunity and the elderly.

To avoid refrigerator bacteria harming your health, it is best to do the following:

● Clean the refrigerator regularly: Clean the refrigerator at least once a month. Take out all the food in the refrigerator, turn off the refrigerator, clean and dry it, and ventilate it for half an hour. It will be difficult for pathogenic bacteria to survive in the refrigerator.

● Put food in the right place: The more types of food you store in the refrigerator and the longer you store it, the more "killers" there will be in the refrigerator. It is best not to fill the refrigerator more than 70% full to facilitate the circulation of cold air and ensure that the temperature meets the standard. It is best to buy a one-time consumption of milk. If you really can't finish it, it is recommended not to store it again. Orange juice and other beverages should be tightly covered and refrigerated after opening, generally not more than 48 hours.

● Keep raw and cooked food separate to avoid cross infection: put cooked food on top and raw food on the bottom. Rice and cooked food must be fully heated before eating after being taken out of the refrigerator.

The above popular science content topics are from

Analysis of bacterial resistance in Peking Union Medical College Hospital (2019)

Peking Union Medical College Journal

Editor: Liu Yang and Zhao Na

Proofread by Li Na, Li Yule, and Dong Zhe

Producer: Wu Wenming