Is there nitrite in hot pot? 7 tips for eating hot pot healthily

There was a food safety news recently, saying that nitrite was detected in "self-heating hot pot".

This news did not cause much emotional reaction among diners, because after years of popular science education on food safety, netizens have already established the scientific rationale that "the dose determines the toxicity".

As we can see from the title, the amount of nitrite detected in the self-heating hot pot is relatively limited. If the content is really high, the word "detected" will 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 7.10mg/kg and 7.95mg/kg, respectively, which neither exceeded the standard for processed vegetables nor the standard for processed meat.

Based on this content, to reach the amount of nitrite food poisoning, it means eating at least ten kilograms of self-heating hot pot food, which is obviously impossible.

So, if you want to eat self-heating hot pot, you can continue to eat it happily.

There may not be many people who eat self-heating hot pot, but there are many people who eat 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:

The first 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;

Second, whether the oil used in 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 soup 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 the strict inspection and control of regulatory authorities. The quality of oils in hot pot bases and dipping sauces is also related to the self-discipline of the production companies, as well as 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 (Yu Jiaqi et al., 2020).

However, when a large amount of heavy-flavored seasonings are added, consumers may not be able to taste it, and thus consume more oxidized fat.

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, and Enoki mushrooms as the main ingredients to make hot pot soup and measured the heavy metal content in it. The results showed 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 (Zhu Yunlong et al., 2015).

There is also a study comparing the dissolution of heavy metals in copper, stainless steel and ceramic pots after long-term boiling (Ye Jun, 2011). The results showed that heavy metals were almost not dissolved when boiled in water, but if 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, as well as 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. There are meat, seafood, and vegetables in the hot pot. Because nitrite is easily soluble in water, the nitrite in these foods will run into the hot pot soup during cooking.

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 may not be eaten 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 (like being soaked in water), then the risk of excessive nitrite is still minimal. Once the leaves fall off or even become waterlogged, the nitrite content is out of control and you must not eat it! In this regard, the vegetables in hot pot restaurants are usually better cooked and can guarantee the "appearance", while the vegetables at home may wilt and fall leaves but you are reluctant to throw them away...

However, even if leafy and root vegetables look fresh, the nitrates they contain will be dissolved in the hot pot soup and, after repeated tumbling and cooking, some of them will be converted into nitrites (we learned this reaction in high school chemistry class). Chinese cabbage, baby cabbage, various green leafy vegetables, and radishes, which are 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 and black 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 made properly, are contaminated with 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. However, the content is very low, only a few milligrams per kilogram. However, the nitrite content in stale fish and shrimp, as well as 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 30~70mg/kg (depending on the specific product, and some countries even relax it to 100mg/kg). This is much higher than the content measured in self-heating hot pot... Do you still want to eat it...

When eating hot pot in a restaurant, you should be especially careful to observe whether the meat is marinated with sodium nitrite.

Some stores may add sodium nitrite to the meat to make it less prone to spoilage, to make it pink after cooking and look good, and to make it taste like ham. In order to make the meat tender, meat tenderizer is used to treat the meat, and sodium nitrite may also be added to the meat tenderizer. The sodium nitrite added during the marinating process 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 (Wu Xiaoping et al., 2019). 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 1.4mg/kg, and the highest is 4.0mg/kg, which is quite safe; the average nitrite content of the tail soup is 5.1mg/kg, which is not high overall; but the maximum value is 58mg/kg, which is already worrying and not suitable for drinking.

4 Other sources

In addition, hot pot seasoning also contains a small amount of nitrite, but its content usually meets national standards (Huang Shu et al., 2019). 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 large, so there is basically no need to worry about the risk of poisoning.

By the way, nitrite is a toxic substance, but it is not a "highly toxic" substance. If it is a highly toxic substance, a few milligrams can kill people, such as arsenic, aflatoxin, and fumonisin. 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

Purine does not appear in the soup out of thin air. It is either contained in the soup base or the purine in the ingredients dissolves 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 to the soup, the purine content in the soup will continue to rise. After the meat is first boiled in the soup, the purine content in the meat will decrease. But as the soup becomes thicker, the purine content becomes higher and higher, and later, the content in the soup will even exceed the content in the meat. At this time, the purine content in the boiled meat will not decrease at all. Even the vegetables boiled 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.

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 the vegetables for too long. The longer the cooking time, the greater the risk that some of the nitrates in the vegetables will turn into nitrites and heavy metals will be leached out. It is best to eat them within 1 hour.

2. Control the total amount of fish and meat, and the ratio of fish and meat to vegetables should be 1:1 to 1:2. This can not only provide enough vitamin C and antioxidants, which is helpful to reduce the formation of nitrosamine carcinogens, but also maintain nutritional balance.

Especially when eating self-heating hot pot, because the vegetables are very limited and not fresh enough, it is better to add some juicy green leafy vegetables or two tomatoes. This way, there is no worry about nitrite, and it 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 carry away the fat on the surface of the soup. So you might as well 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 they don’t taste 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 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. It is better to eat more vegetables and less meat.

Finally, there is a research result worth mentioning. A master's thesis study found that after eating a hot pot meal at night, the cortisol level in the subjects' plasma will increase significantly, which may have an impact on the stress hormone level the next day. This reminds us that eating hot pot is pleasant for a while, but it may make us more nervous and stressed the next day...

References:

Yu Jiaqi, Wang Junlin, Shuangquan, et al. Study on the quality change of hot pot dipping sauce during storage. Chinese Condiments, 2020, 45(04): 29-33

Xia Ling. Study on the distribution of cadmium, lead, chromium and arsenic in the process of hot pot soup base cooking. Master's degree thesis of Southwest University,

Zhu Yunlong, Wang Ronglan, Zuo Junying. Safety study of edible mushroom hot pot soup. Food Science, 2015, 36(18): 182-185

Ye Jun. Comparative study on heavy metal dissolution from hot pot containers. Journal of Gansu Agricultural University, 2011, 46(03):156-160

Huang Shu, Qiu Chao, Yan Chun. Determination of nitrite content in food: Taking hot pot soup base as an example. Food Science and Economy. 2019, 44(05): 73-75, 83

Wu Xiaoping, Shi Zhenyin, Wang Yuming. Analysis on the changes of nitrite content in hot pot soup and hot pot soup in Gansu Province. Journal of Preventive Medicine Information. 2019, 35(09): 961-963+969.

Zhang Xiaohong. Establishment of normal reference values ​​for salivary cortisol and the effects of type 2 diabetes and hotpot consumption on changes in cortisol levels. Master's thesis, North Sichuan Medical College. 2016

Source: Fan Zhihong_Original Nutrition Information