7 tips for eating hot pot healthily

Recently, there was a food safety news report that nitrite was detected in "self-heating hot pot". This news did not cause much emotional reaction among diners. After years of popular science education on food safety, netizens have established the scientific concept of "dose determines toxicity". As we can see from the title, the amount of nitrite detected in self-heating hot pot is relatively limited. If the content is really high, the word "detected" would not be used. The word "detected" is now usually used in the context of "can be detected, but not exceeding the standard".

The two products tested this time had the highest nitrite content of 7.10 mg/kg and 7.95 mg/kg respectively. They did not exceed the standard for processed vegetables or processed meat. According to this content, to reach the level of nitrite food poisoning, it means eating at least 10 kilograms of self-heating hot pot food, which is obviously impossible.

Therefore, if you want to eat self-heating hot pot, you can continue to eat happily. There may not be many people eating self-heating hot pot, but there are many people eating ordinary hot pot.

Someone asked me: Is there a nitrite problem in ordinary hot pot? I have heard that hot pot soup not only has high purine problems, but also has a high nitrite problem!

I checked the literature and found that the research on food safety of hot pot mainly focuses on the following aspects:

One is the detection of the content of several alkaloids such as papaverine in hot pot base, as well as the detection of the content of food additives.

The second is whether the oil used in the hot pot base and hot pot dipping sauce is safe and qualified, and whether it is over-oxidized.

The third is the dissolution of heavy metals in hot pot base.

Fourth, the nitrite content in hot pot.

In addition, there are also studies on the changes of purine in hot pot cooking. Because purine is not a toxic substance, it has nothing to do with food safety and is only related to patients with hyperuricemia and gout who need to pay attention to the purine content.

Ingredients such as papaverine and other food additives are intentionally added by humans, so we can only rely on regulatory authorities to conduct strict inspections and controls. The quality of the oils in hot pot bases and dipping sauces is also related to the self-discipline of the manufacturers, as well as the storage conditions and storage time. If the time is too long or the storage temperature is too high, the quality will continue to decline, the oxidation and rancidity index will gradually increase, and the flavor will also deteriorate. However, when a large amount of heavy-tasting seasonings are added, consumers may not be able to taste it, and thus consume more oxidized fats.

The composition of heavy metals is quite complex. In addition to coming from the base soup, base ingredients and hot pot ingredients, it also comes from the hot pot containers, such as copper pots or ceramic pots.

A study used Matsutake, Agrocybe oleracea, Shiitake, Enoki mushrooms and other mushrooms as the main ingredients, boiled them into hot pot soup, and measured the heavy metal content in it. It was found that after 5 hours, the cadmium content in the soup exceeded the standard, but the content of other heavy metals was still within the safe range.

Another study compared the dissolution of heavy metals in copper, stainless steel and ceramic pots after long-term boiling. The results showed that almost no heavy metals were dissolved when boiling in water, but if the sauerkraut was boiled for 6 hours, the copper pot dissolved more mercury, lead and a small amount of cadmium, nickel and chromium; the stainless steel pot dissolved more lead, chromium, nickel and a small amount of cadmium; the ceramic pot dissolved a small amount of mercury and trace amounts of lead and cadmium. The researchers suggested that it is relatively safer to use a ceramic pot when eating sauerkraut hot pot, and the cooking time should be controlled within 2 hours.

Personally, I think the specific risks are closely related to the quality of the product used in the pot, and cannot be generalized, but we must be more cautious when cooking acidic foods, and it is better not to use metal containers.

Here I will focus on discussing the issue of nitrite in hot pot, and then briefly talk about purine and other issues.

Nitrite used to be a major hidden danger in the food safety of hot pot food. In general, after 2010, due to the increasingly standardized food safety management in my country, nitrite poisoning caused by eating hot pot has rarely occurred. Nevertheless, this issue is still worthy of our attention. Because when the nitrite content increases, it may also react with amine substances dissolved in meat, fish, and seafood during the long cooking process to synthesize nitrosamine carcinogens.

Where does the nitrite in hot pot come from?

Hot pot will not produce nitrite out of thin air. It is either brought in by the raw materials or converted from nitrates.

Because nitrite is widely present in many foods, including vegetables and processed meat products. There are meat, seafood, vegetables, etc. in the hot pot, and nitrite is easily soluble in water, so the nitrite in these foods will run into the hot pot soup as it is cooked.

1. Fresh vegetables

The nitrite content of fresh vegetables is very low, usually less than 4 mg/kg. However, leafy vegetables and root vegetables contain a lot of nitrates. They are not toxic in themselves, but can provide raw materials for making nitrites.

After harvesting, vegetables still need to be transported and sold. After being purchased by catering companies, they are not necessarily consumed on the same day. As the storage time increases, the nitrite content in raw vegetables will gradually increase. Even at home, in the refrigerator, it will slowly increase, for example, from a few milligrams per kilogram to more than ten milligrams. Moreover, in many restaurants, they may not be kept in refrigerated conditions at all.

However, if you take out the vegetables to cook and see that they are in good condition, without wilting, yellowing, falling leaves or even waterlogging (as if they have been soaked in water), then the risk of excessive nitrite is still minimal. Once they start to fall leaves or even become waterlogged, the nitrite content is out of control and you should never eat them! In this sense, the vegetables in hot pot restaurants are usually cooked better and can guarantee the "appearance", while the vegetables at home may wilt and fall leaves but you still can't bear to throw them away.

However, even if leafy and root vegetables look fresh, the nitrates they contain will be converted into nitrites after being dissolved in the hot pot soup and repeatedly tumbled and cooked. Chinese cabbage, baby cabbage, various green leafy vegetables, radishes and other common vegetables in hot pot are all nitrate-rich ingredients. Therefore, after cooking a large amount of vegetables, the nitrate content in the hot pot soup will gradually increase over time.

2. Processed vegetables

Some sauerkraut, kimchi, dried mushrooms, fungus, and even processed vegetable products such as canned vegetables and quick-frozen vegetables may also be put into the hot pot.

According to my country's food safety standards, the nitrite content of processed vegetable products should be less than 20 mg/kg. For example, kimchi, sauerkraut, salted vegetables, pickled vegetables, quick-frozen vegetables, and canned vegetables all need to follow this standard.

Qualified processed vegetable products are actually quite safe. After blanching and cooking, the nitrate content in the raw materials has been reduced, and the risk of producing a large amount of nitrite is extremely small.

Dried vegetables need to be soaked, and most of the nitrates and nitrites in them will be dissolved during the soaking process, so there is no risk of producing large amounts of nitrite.

However, when restaurants serve fermented vegetables such as sauerkraut and kimchi, if the homemade products are not produced properly, are contaminated by bacteria, and the fermentation time is not more than 20 days, it is very easy to introduce too much nitrite.

3. Fish, seafood and other animal ingredients

Fresh ingredients such as meat and fish also naturally contain nitrite. But the content is very low, only a few milligrams per kilogram. However, the nitrite content in stale fish and shrimp and various processed meat products is much higher. For example, sausages, ham, bacon, luncheon meat, etc., all contain nitrite. The permitted residual amount in my country is 30-70 mg/kg (depending on the specific product, and some countries even relax it to 100 mg/kg). This is much higher than the content measured in the self-heating hot pot.

When eating hot pot in a restaurant, be especially careful to observe whether the meat is marinated with sodium nitrite. Some stores may add sodium nitrite to marinate the meat in order to prevent it from spoiling, to make it pink after being cooked, and to make it taste like ham. In order to tenderize the meat, tenderizer powder is used to treat the meat, and tenderizer powder products may also contain sodium nitrite. The sodium nitrite added during marinating may dissolve from the meat and run into the soup.

The Gansu Provincial Center for Disease Control and Prevention has a literature report that 45 hot pot soups from 24 urban and rural hot pot restaurants were tested. The results showed that the detection rate of nitrite was 74.4%. Comparing the content of the first soup (the soup at the beginning of eating) and the tail soup (the soup at the end of eating), it was found that after eating meat and vegetable ingredients, the nitrite content in the tail soup would increase to varying degrees, and the highest increase could reach 116 times that of the first soup. The average content of the first soup is 1.4 mg/kg, and the highest is 4.0 mg/kg, which is quite safe; the average nitrite content of the tail soup is 5.1 mg/kg, which is not high overall; but the maximum value is 58 mg/kg, this concentration is already worrying and is not suitable for drinking anymore.

4. Other sources

In addition, hot pot seasoning also contains a small amount of nitrite, but its content usually meets national standards. In hot pot seasoning, the added chives, scallions, chopped coriander, etc., if the raw materials are not fresh, may introduce a small amount of nitrite. However, after all, the total amount consumed is not much, so there is basically no need to worry about the risk of poisoning.

By the way, nitrite is a toxic substance, but not a highly toxic substance. If it were a highly toxic substance, a few milligrams would kill a person, such as arsenic, aflatoxin, fumonisin, etc. As for nitrite, you have to take hundreds of milligrams at a time to have a poisoning reaction.

Let’s talk about the purine problem in hot pot

Purines do not appear in the soup out of thin air. Purines are either present in the soup base or dissolved in the ingredients and run into the soup. The purine content in hot pot soup may be affected by several factors:

1. What kind of soup base is used? If you use seafood or meat soup base, the purine content will be higher. If you use plain water as the soup base, the purine content in the soup will be very low when you first eat it.

2. How much fish and seafood are added. If you only cook green vegetables, not much purine will be produced. Even if you cook mushrooms, there will not be much purine, because the purine content in fresh mushrooms is lower than that in meat. The so-called high purine content in mushrooms comes from the data of dried mushrooms. Who would eat so many dried mushrooms? The content will be greatly reduced after soaking in water.

As fish, shrimp, and meat are added, the purine content in the soup will continue to rise. After the meat is first dipped in the soup, the purine content in the meat will decrease. But as the soup becomes thicker, the purine content increases, and eventually, the content in the soup even exceeds that in the meat. At this point, the purine content in the meat that has been dipped in the soup will not decrease at all. Even the vegetables dipped in the soup will have a higher purine content because the purine in the soup enters the vegetables.

3. The cooking time and concentration of the soup. If you add too much water, the soup will be diluted. If you add more ingredients and less water, the content of the soup will increase.

7 tips for eating hot pot healthily

Considering the nutritional issues together, there are several key points to pay attention to if you want to eat hot pot safely and healthily:

1. Don’t cook hot pot for too long. The longer the time, the greater the risk that some nitrates in the vegetables will turn into nitrites, and the risk of heavy metals dissolving out. It is best to eat within 1 hour.

2. Control the total amount of fish and meat. The ratio of fish, meat and vegetables should be 1:1 to 1:2. This way, you can get enough vitamin C and antioxidants, which is helpful to reduce the formation of nitrosamine carcinogens, and maintain nutritional balance. Especially when eating self-heating hot pot, because the vegetables are very limited and not fresh enough, it is best to add some juicy green leafy vegetables or two tomatoes. This way, you don’t have to worry about nitrites, and you can increase vitamins and dietary fiber and improve nutritional balance.

3. Do not cook vegetables for too long and take them out in time before eating to avoid excessive loss of vitamins and antioxidants.

4. If the soup already contains a lot of fat, adding vegetables may cause the fat on the surface of the soup to be absorbed. So it is best to skim off the floating oil on the surface before adding the vegetables.

5. Pay attention to the freshness of various ingredients, and also pay attention to whether sodium nitrite has been added to meat ingredients. Meat with sodium nitrite added will appear pink after being cooked, rather than light brown or white.

6. It is best to choose a clear soup pot, which has a lower starting content of salt and fat.

7. Pay attention to the freshness of the hot pot base and dipping sauce. If you feel that the taste is not fresh, don't eat at this restaurant next time.

If you need to control the level of uric acid in your blood, you should eat less fish, meat, and seafood, and avoid drinking hot pot soup that has been cooked for a long time. If you want to drink soup, drink it early before the purine content rises. If you want to eat meat, eat it at the beginning of the hot pot, when the purine content of the meat after hot pot can be lower. You may as well eat more vegetables and less meat.