It has long been believed that eating fruits and vegetables raw helps you absorb more nutrients. However, recently, researchers from Purdue University in the USA announced that Listeria, a dangerous pathogen, has been found in leafy lettuce (commonly used in salads), adding to the concerns of those who love lettuce, including in cold dishes and salads.
"Listeria most often contaminates eggs, dairy products, and meat and their products, and has also been found on the surface of fruits and vegetables. But this new discovery shows that Listeria can invade the interior of vegetables, making traditional methods like washing, peeling, and disinfecting less effective," Yun Wuxin, a Ph.D. in food engineering from the Department of Agricultural and Biological Engineering at Purdue University, told the Life Times reporter. Healthy adults infected with Listeria often experience symptoms like diarrhea and vomiting; however, for vulnerable groups such as pregnant women, the elderly, children, and patients with chronic illnesses, the consequences can be quite severe. Taking pregnant women as an example, their infection rate is not higher than that of the general population, but once infected, it can easily lead to complications or cross the placental barrier, causing miscarriage, and in severe cases, it can be life-threatening. The incubation period for Listeria is several to dozens of days and is not easily noticed because few people pay attention to what they ate 20 days ago.
Regarding whether to continue eating vegetables raw, Yun Wuxin stated that there is definitely a risk of Listeria infection from eating raw vegetables. For healthy adults, if you enjoy eating them raw, there's no need to give it up, but you should pay attention to washing (which can remove surface Listeria). After all, the probability of Listeria infection is very small, and even if infected, it is unlikely to be fatal. Pregnant women, the elderly, and children should try to avoid cold dishes or salads and are best to eat them after cooking. Besides Listeria, eating raw vegetables also carries a risk of E. coli infection, which is also more harmful to the elderly and children. Furthermore, the elderly, children, and those with weak digestion have poor digestive capabilities, and eating raw food can easily cause gastrointestinal discomfort.
How can ordinary people reduce the risk of pathogenic infection? Yun Wuxin told reporters that the following points should be noted:
First, cook thoroughly. This is the most reliable method. Listeria is killed when the core temperature of food reaches 72°C. Vegetables can be boiled or stir-fried for a few minutes, or heated in a microwave until the inside is very hot.
Second, blanch with boiling water before eating raw. Before eating raw fruits and vegetables like cucumbers, tomatoes, radishes, and melons, first blanch the skins in boiling water. For cold dishes made from cabbage, lettuce, carrots, and other vegetables, you can also blanch them slightly, which can kill bacteria without significantly affecting the nutrition and taste.
Third, buy from regular supermarkets, as farm produce carries greater risks. If you prefer to eat raw vegetables, it is recommended to buy vegetables and fruits from large agricultural production bases in regular supermarkets, as their planting environments and hygiene conditions are more guaranteed. Yun Wuxin emphasized that many people believe that farm-produced fruits and vegetables without chemical fertilizers or pesticides are more natural and safe. In fact, farm produce carries greater risks. On one hand, there are more animals like chickens and ducks in rural areas, providing more opportunities for pathogen transmission. On the other hand, rural areas often use unfermented farm manure, which contains more pathogens. In comparison, chemical fertilizers are safer.
Finally, Listeria is not afraid of cold and actually prefers the refrigerator. Therefore, leftover cold dishes should be thrown away promptly and not stored in the fridge. Other dishes can also become contaminated a second time in the refrigerator, so they must be thoroughly reheated before eating. As the weather gets warmer, the season for foodborne illnesses is approaching. Everyone must follow the Five Keys to Food Safety (keep clean, separate raw and cooked, cook thoroughly, keep food at safe temperatures, use safe water and raw materials) to actively and effectively prevent pathogenic infections.