The crispy and delicious kimchi uses a fresh and sour taste to dissolve the greasy feeling of the dishes, so it is deeply loved by the majority of diners. However, the claim that “Kimchi causes cancer” has been repeatedly brought up, which makes many people shy away from Kimchi. In fact, “Kimchi causes cancer” is a misunderstanding caused by partial generalization.
Some people think that “kimchi is carcinogenic” because nitrite may be produced in kimchi, and after nitrite enters the human body, it will convert strong carcinogens – nitrosamines in the acidic environment of the stomach. When the intake of nitrite in the human body is 0.2 to 0.5 grams, it will cause poisoning, and when the intake exceeds 3 grams, it will lead to death. However, we don’t have to talk about the discoloration of nitrite, because we can’t “talk about toxicity aside from the dose”, and only excessive intake of nitrite will cause harm to the human body.
Microorganisms in the kimchi jar
It should be pointed out that vegetables themselves contain nitrates and a small amount of nitrites after they are picked. Nitrate itself is not toxic, but in the early stage of kimchi fermentation, under the action of nitrate-reducing bacteria, a large amount of nitrate in vegetables will be converted into nitrite. In fact, the nitrite in kimchi eventually degrades itself. With the reduction of oxygen during the fermentation process, the reproduction of miscellaneous bacteria is limited or even death occurs, and lactic acid bacteria gradually evolve into the dominant flora. After the lactic acid bacteria are “up”, kimchi is safe – first, the lactic acid bacteria can inhibit the activity of nitrate-reducing bacteria, thereby inhibiting the production of nitrite; second, the lactic acid bacteria can produce nitrite reductase, which promotes the further development of nitrite. transformation; thirdly, lactic acid bacteria metabolism will produce lactic acid, which can rapidly reduce the pH value in the fermentation system and accelerate the reduction rate of nitrite, thereby reducing the nitrite content in kimchi. In addition, in the fermentation process of kimchi, fresh ginger, fresh pepper, green onion, onion and other auxiliary materials are added. These auxiliary materials can inhibit the activity of nitrate-reducing bacteria, thereby reducing the formation of nitrite. Therefore, at the end of the entire fermentation process, the nitrite content in kimchi is extremely low. Some researchers have put forward the theory of nitrogen/ammonia conversion of nitrite in kimchi, thinking that the nitrite in kimchi will eventually be reduced to nitrogen or ammonia.
Triple Quadrupole GC-MS (an analytical instrument used during Kimchi research)
In addition, the researchers found that the nitrite content of kimchi products on the domestic market was below 5 mg per kilogram, far below the national limit (20 mg per kilogram). According to the estimation of the highest concentration of nitrite in these pickles, a person weighing 60 kilograms needs to eat more than 2.5 kilograms of pickles a day to exceed the allowable daily intake of nitrite recommended by the World Health Organization. In fact, it is impossible for one person to eat so many kimchi at one time. Moreover, in our daily diet, the vast majority of nitrites are excreted in the body like “passengers” in the urine, and only under specific conditions (appropriate pH, microbial flora and temperature) will they be converted into Nitrosamines. Therefore, under normal conditions, dietary nitrite is not harmful to human health.
Hygienically standardized and fermented kimchi has no potential safety hazard of excessive nitrite content, and the lactic acid bacteria in kimchi also have a certain degree of benefit to human health.
Only by understanding the process and principle of kimchi making can you enjoy the delicious taste of kimchi with more peace of mind