A watermelon costs 5 yuan, but the whole family is hospitalized for 5,400 yuan! How harmful is "overnight watermelon" to the body?

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

In the hot summer, watermelon is a must-have delicacy for every family. Many people put the leftovers in the refrigerator and eat them the next day or the day after. Recently, a news report that "a family was poisoned by leftover watermelon and spent 5,400 yuan in hospital" attracted attention, and many netizens said that they would never dare to eat leftover watermelon again.

According to reports, Mr. Zhang from Songyuan, Jilin spent 10 yuan to buy half a watermelon. He put the remaining 1/4 in the refrigerator and ate it two days later. As a result, the whole family started to complain in the middle of the night. At 3 a.m., he went to the emergency room. The examination results showed that it was gastroenteritis caused by mild food poisoning. The family spent 5,400 yuan on treatment. Mr. Zhang later lamented that he did not expect that a 5-yuan watermelon would cause such consequences.

Wang Guoyi, a postdoctoral fellow in nutrition and food safety at China Agricultural University, told reporters that improperly stored watermelons do pose a great food safety risk. Watermelons have high water and sugar content, and the high temperature in summer is very suitable for the growth and reproduction of pathogenic bacteria. It is not certain when the half watermelon bought by Mr. Zhang in the news was cut. If it has been placed under high temperature for two or three hours or even longer after being cut, it means that the pathogenic bacteria have multiplied in large numbers. Even if it is put in the refrigerator after taking it home, the "base number" of bacteria will be too large, resulting in a serious excess of pathogenic bacteria.

In addition to the pathogenic bacteria produced by long-term storage of watermelon, there may be some psychrophilic bacteria in the refrigerator, which can still grow and reproduce at 4°C, which can further contaminate the watermelon. A study conducted smear sampling in the refrigerators of residents in five urban areas of Beijing. The results showed that among the 718 samples, the positive rate of coliform group was 48.05%, and the positive rates of Listeria monocytogenes (Listeria), Yersinia enterocolitica, and Staphylococcus aureus were 0.14%, 0.42%, and 1.25%, respectively. If the watermelon is placed in such an environment for two days, the chance of food poisoning will also increase greatly. If the person eating watermelon is a pregnant woman, the elderly or other people with low immune function, the consequences will be even more terrible. If pregnant women are infected with Listeria, it will directly affect the health of the fetus. It can cause septic abortion in early pregnancy, and infection in late pregnancy often leads to premature birth and stillbirth. In addition, if you don't wash your hands when cutting watermelon, or if the knife, cutting board, etc. are not cleaned, pathogens may also be introduced, increasing the risk of food safety.

To eat watermelon safely, you need to pay attention to the following points. First, if you don’t know when the watermelon was cut, it is best not to buy it. If you buy it, you must eat it on the same day and cannot save it for the next day or even the third day. Second, clean the knife, watermelon, hands and cutting board before cutting the watermelon. Do not mix them with the cutting board and knife for cutting raw meat. Third, avoid touching the flesh of the watermelon with your hands if you can’t finish it. Wrap it with clean plastic wrap immediately after cutting it, put it in the refrigerator, and keep it away from eggs, raw meat, seafood and other foods. Fourth, experiments show that watermelon wrapped in plastic wrap can be kept in the refrigerator for 7 days, but it is still recommended that everyone eat it as soon as possible and try not to store it for more than two days. Because home conditions are different from laboratory conditions, and the longer the storage time, the greater the food safety risk and the worse the taste.

Wang Guoyi reminded that in addition to watermelon, the following types of food are also prone to spoilage when the weather is hot, so we need to be vigilant. First, protein-rich foods such as milk, soy milk, and tofu. It is best not to buy bulk tofu at room temperature. If you can't finish milk and soy milk after opening, refrigerate them immediately; second, fat-rich foods such as nuts and fried foods should be thrown away if they have a rancid smell; third, foods such as cold dishes that have not been heated should be cooked and eaten immediately; fourth, wet rice noodles such as rice noodles and rice rolls are easily contaminated by Pseudomonas cocovenenans, so they must be purchased through formal channels and eaten as soon as possible. (Global Times Health Client Reporter Wang Shuying)