Recently, sauerkraut and kimchi have been frequently searched.
For many people, kimchi is a very controversial food. Some people think that kimchi contains lactic acid bacteria and is rich in nutrients, but some people think that kimchi contains carcinogens and is unhealthy. Is it a nutritional supplement or a carcinogen? Can you eat kimchi with confidence in the future?
I. Kimchi is rich in lactic acid bacteria and rich in nutrients?
Sauerkraut and kimchi are inseparable from the fermentation of lactic acid bacteria.
In ancient times, the ancients could not isolate the bacteria, and the sauerkraut in Laotan mostly relied on the lactic acid bacteria that came with fresh vegetables. During fermentation, the vegetables are tightly stacked layer by layer. In an oxygen-deficient environment, anaerobic lactic acid bacteria become the “predominant bacteria”, converting the free sugar in the vegetables into lactic acid, and the acidic conditions will inhibit pathogenic and spoilage microorganisms, allowing sauerkraut food safety is guaranteed.
In this way, lactic acid bacteria are the soul of sauerkraut and kimchi. If there is no lactic acid bacteria, there will be no safe and delicious kimchi.
But it should be noted that lactic acid bacteria are not always retained in sauerkraut. National Registered Dietitian Yu Liang said that when vegetables reach 37 degrees during fermentation, a large number of lactic acid bacteria will multiply. But when we cook sauerkraut, the lactic acid bacteria will be killed within 30 minutes when the temperature reaches 60 °C. When it reaches 100 °C, it only takes 3 minutes to kill the lactic acid bacteria.
It can be said that stewed sauerkraut generally does not contain lactic acid bacteria. Lactic acid bacteria are probiotics in the body. Does it mean that eating raw sauerkraut can supplement lactic acid bacteria, which is good for health?
Here, Xiao Ai does not recommend that you eat raw. Although sauerkraut contains lactic acid bacteria, it is also in the production and fermentation process, which may be due to hygiene issues and other harmful bacteria. Eating sauerkraut raw will not only fail to exert the value of probiotics, but may also cause diarrhea, vomiting and other problems due to the intake of harmful bacteria, which is detrimental to health.
It should also be reminded that although kimchi and sauerkraut retain some of the nutrients of fresh vegetables, the nutritional value is not comparable to that of fresh vegetables. The original purpose of making pickles is to prolong the shelf life of vegetables, which may be lost in terms of nutrition. Therefore, it is too far-fetched to say that pickles have high nutritional value.
Second, Kimchi contains nitrite, which can cause cancer?
With the improvement of people’s health awareness, many people know that preserved food contains a lot of nitrite, and nitrite is carcinogenic, and many people are discouraged. After all, how is the nitrite in kimchi produced? Are the dishes made with sauerkraut not edible?
The nitrite in kimchi mainly comes from three aspects:
First, vegetables absorb nitrogen fertilizer and nitrogen in the soil, accumulating no toxic nitrates. After pickling, these nitrates are converted into nitrites by bacteria.
Secondly, when the vegetables are pickled, the temperature is high, the salt is not enough, and the pickling time is short, which will cause bacteria to multiply, causing pollution, and the nitrate will be reduced to sub- nitrates.
Third, the salt itself contains impurities in pickles, such as nitrite, nitrate, etc., which may also lead to the production of nitrite.
Nitrite is extremely permeable in the body. For pregnant women, it can directly penetrate the placenta and affect the fetus. After ordinary people use nitrite, it needs to be metabolized by the liver, which will not only increase the burden on the liver, but also cause toxic substances to remain in the liver, causing nitrite poisoning. carcinogenic effects.
In this way, if you eat kimchi often, wouldn’t you eat carcinogens in your mouth?
In response, Chen Gong, an expert from China Kimchi Industry Technology Research Institute said that through research on nearly 10,000 kinds of kimchi in the market, it was found that the nitrite of kimchi products is 5mg/ kg or less.
According to the regulations of the United Nations, the allowable daily intake of nitrite is 0.2mg/kg body weight, that is, a 50kg adult can consume about 10mg of nitrite >, and according to the nitrite content of kimchi and mustard, it is safe to eat about 5 catties of kimchi every day, and consumers do not need to worry too much.
Third, how many days is it safe to marinate kimchi?
Kimchi occupies a place in the dietary structure of Chinese residents. The nitrite content in fresh vegetables varies according to the variety of vegetables. In order to control or reduce the content of nitrite, an experiment was carried out at the Health and Epidemic Prevention Station of Qiqihar City, Heilongjiang Province.
The experimenter selected local cabbage and cabbage, put them in boiling water to kill the greens, drained them, and then placed them in clean water under pressure for natural pickling and fermentation, and sampling nitrite every day for measurement. After 10 consecutive days, measurements were made at 5-day intervals, and the pickling and fermentation time was 20 days.
The study found that the nitrite content in household pickled kimchi would initially increase with the extension of the fermentation days, but after the 6th day, it reached the peak and then gradually decreased, After 20 days, the nitrite in the kimchi has basically been completely disintegrated.
The content of nitrite in kimchi over time:
Day 1: 5.8ml/kg for cabbage and 5.8ml/kg for cabbage It is 6.1ml/kg.
Day 4: 133.0ml/kg for cabbage and 157.1ml/kg for cabbage.
Day 6: 213.3ml/kg for cabbage and 246.0m for cabbagel/kg.
Day 9: 82.5ml/kg for cabbage and 86.9ml/kg for cabbage.
Day 20: 1.5ml/kg for cabbage and 1.7ml/kg for cabbage.
It can be seen that during the fermentation process of kimchi, the dynamic change of nitrite showed a trend of rising first and then falling: the content of nitrite began to increase after starting to pickle, and it increased significantly on the 4th day. It peaked at 6 days and continued to decline thereafter.
4. Who should eat less kimchi?
The carcinogenicity of kimchi is based on a certain dose. As long as the pickled vegetables are thoroughly marinated, it is relatively safe to eat. However, kimchi is not edible for everyone. For these 4 types of people, eating kimchi frequently is likely to aggravate the disease.
1. Patients with hypertension, renal insufficiency, cardiovascular and cerebrovascular diseases, etc.
Salt-preserved vegetables are all high-salt foods, which are harmful to hypertension. , renal insufficiency and other patients, it is necessary to strictly follow the low-salt diet standard and eat pickled vegetables, which will undoubtedly affect the disease.
2. People with digestive system diseases such as gastritis and gastric ulcers
Kimchi appetizers will promote appetite, but at the same time, because it is not easy to digest, it will also stimulate gastric acid secretion , increase the burden on the stomach.
3. Those with family history of gastric cancer, esophageal cancer, liver cancer and other malignant tumors
According to the prevalence According to medical research, long-term consumption of pickled vegetables is a risk factor for digestive system cancers such as gastric cancer and esophageal cancer in some regions. Therefore, people with a family history of digestive system cancer are not suitable to eat kimchi regularly.
4. The elderly, pregnant women, children and other special groups
The salt content of kimchi is too high. Excessive intake of kimchi will increase the burden on the kidneys. It is not suitable for the elderly. edible. In addition, considering the issue of food safety, pregnant women and children are not suitable for consumption due to their weak physique.
Eating kimchi in moderation does not pose too much threat to health, and changing the taste occasionally can also help increase appetite. It should be noted that pickled kimchi at home must be preserved for at least 20 days; in addition, when eating kimchi, it should also be accompanied by some fresh vegetables and fruits to ensure a balanced diet.
References;
[1] “Pickled sauerkraut contains lactic acid bacteria, are there lactic acid bacteria after cooking? “.Nutrition Speaker.2019-01-02
[2]”Where does the nitrite in pickles come from? Journal of Public Health. 2015-11-26
[3] “Study on the change of nitrite content in pickled vegetables” [J]. Journal of Qiqihar Medical College. 2002 Vol. 23 No. 5