Cold dishes are also "dangerous goods". How should we eat cold dishes healthily in summer?

Author: Xue Qingxin, registered dietitian

Reviewer: Zhang Yu, researcher at Chinese Center for Disease Control and Prevention

In the hot summer, cold dishes have become the favorite of most people. Whenever you are sweating profusely, a plate of refreshing cold dishes can especially capture people's hearts. However, we can't be careless when eating cold dishes in summer. There are also some precautions for eating cold dishes in summer. If you are careless and don't pay attention, it is likely to cause harm to your body.

A few days ago, there was a news story: a 67-year-old man ate a plate of overnight salad cucumbers and was poisoned and sent to the hospital! The doctor diagnosed the cause as "bacterial infection leading to sepsis, which in turn led to septic shock." The culprit was the overnight salad cucumbers. Are cucumbers poisonous? Of course not. It was mainly because the improper storage of the salad caused bacteria to grow, and the man got food poisoning after eating it.

You see, a small plate of cold dishes can cause big problems if consumed improperly. Next, let’s talk about eating cold dishes in summer so that everyone can enjoy delicious food safely this summer.

1. Which ingredients should be prepared with caution when served cold?

Although cold dishes are convenient and quick, not all vegetables can be eaten directly as cold dishes. Some ingredients need to be pre-processed first, otherwise it may cause food poisoning.

* String beans and green beans : They cannot be eaten raw! If they are not cooked thoroughly, they will contain saponins and lectins, which can cause poisoning and even be fatal!

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* Fungus : Generally, we buy dried fungus, which needs to be soaked before cooking. However, if fungus is soaked for too long, it may produce fumonisin, which is highly toxic to humans and animals and can cause toxic hepatitis. In severe cases, it can also cause multiple organ failure and even death! The most terrifying thing is that the mortality rate after poisoning is over 40%, and there is currently no specific antidote. Therefore, it is recommended that fungus be soaked for no more than 4 hours and the water temperature should not exceed 30℃. When mixing it cold, blanch it in water first to remove impurities and microorganisms, which is safer to eat.

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* Aquatic plants : Lotus root, houttuynia cordata, water chestnuts and other aquatic plants may be contaminated by parasites. For example, eating water chestnuts raw is likely to cause infection with ginger worms, which can cause abdominal pain, diarrhea, nausea, fever, and in severe cases, intestinal obstruction or even death. Therefore, if you want to mix these ingredients cold, you must blanch them first and then mix them cold.

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*Vegetables with high oxalic acid content : such as spinach, spring bamboo shoots, water spinach, purslane, etc., have high oxalic acid content, which will affect the absorption and utilization of minerals and increase the risk of kidney stones. They need to be blanched to remove the oxalic acid before being served cold.

* Toona sinensis : Toona sinensis is a vegetable with a high nitrite content. Nitrite may form carcinogens - nitrosamines in the stomach. Excessive nitrite intake will bring some health risks. However, after blanching, the nitrite content will be greatly reduced, so you can eat it with confidence.

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*Fresh daylily : Don’t eat fresh daylily directly! Because some “toxic ingredients” in fresh daylily can cause nausea, vomiting, dry mouth and diarrhea. The latest research shows that the “toxic ingredients” in daylily are co-eluting components of multiple compounds, which are easily soluble in water and can be decomposed by steaming and blanching. They can be eaten safely after cooking.

* Bean sprouts : If you eat bean sprouts in a cold dish, you must blanch them first! Because raw bean sprouts may carry Listeria, which can cause nausea, fever, diarrhea, and even meningitis, which is life-threatening; especially if pregnant women eat them, there is a risk of miscarriage. In addition, raw bean sprouts contain a small amount of trypsin inhibitors, which are anti-nutritional factors that can inhibit the activity of trypsin and chymotrypsin, reduce the digestion and absorption rate of protein, and may make people feel uncomfortable after eating, with symptoms such as nausea and vomiting. Therefore, raw bean sprouts must be heated and boiled before being served cold.

2. Can leftover cold dishes be refrigerated?

It’s best not to eat cold dishes overnight!

This is because many cold dishes are served cold without being heated, and bacteria can easily be mixed into the ingredients themselves or during processing. People also stir the dishes with chopsticks when eating, which increases the probability of the dishes being contaminated. If cold dishes are left overnight, bacteria will multiply more, increasing the risk of dish spoilage and food poisoning. Even if they are placed in the refrigerator, they are easily contaminated by various bacteria, and eating them without heating may also cause food poisoning. In our daily lives, it is also common to have diarrhea after eating cold dishes left overnight.

Therefore, it is best to prepare cold dishes on the same day and try not to eat the leftovers.

3. How to eat cold dishes safely?

In the hot summer, if you want to eat cold dishes healthily and safely, you should follow the following suggestions.

*Purchase of ingredients : You must purchase ingredients from regular channels, preferably in large supermarkets, which have relevant testing procedures and are more secure. If the source of ingredients is inappropriate, there may be risks of pesticide residues and excessive levels; ingredients purchased directly from farmers may be irrigated with manure and may be contaminated with bacteria and insect eggs, such as E. coli, Salmonella, and Staphylococcus aureus.

*Washing ingredients : Wash the ingredients carefully and several times. For ingredients with "firm" skin, such as cucumbers, carrots, zucchini, etc., you can brush them with a soft brush or peel them directly.

*Keep raw and cooked chopping boards separate : Do not use the same chopping board for cutting raw meat and fruits and vegetables. Mixing them can easily lead to cross contamination and increase the risk of food poisoning. Also, wash the chopping board carefully after use and hang it to dry.

*Do a good job of pretreatment : Vegetables that need to be blanched must be blanched to remove oxalic acid and other potentially toxic and harmful substances. Don't be lazy!

* Cook right before eating : Don’t cut the ingredients long in advance and leave them aside. Prolonged exposure to the air will increase the possibility of contamination by microorganisms. Cook only as much as you eat and finish it in one meal. Don’t save the leftover cold dishes for the second meal or the next day. You should know that risking your life to “save” may not be worth the cost. It is better to control the amount and not cook too much.

* Restaurant selection : If you want to eat cold dishes when dining out, you must choose a regular restaurant. Pay attention to the restaurant's business license. If it is marked with words such as "cold food production and sale", you can order cold dishes; if there is no cold food license, the restaurant does not have the conditions to make and sell cold dishes.

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In addition, it is worth noting that drunken shrimps, drunken crabs, sashimi, etc. may contain parasites and bacteria, which may lead to food poisoning, so you should be more cautious when eating them.

References

Ma Wei, Gao Jie, Xing Qian, et al. Safety analysis of fresh daylily[J]. Modern Food, 2021(23):153-155.