Do you know? Open the door | Are the vegetables you pickle yourself safer? Click here to learn how to eat pickled vegetables safely

Written by: Li Caihong, Urumqi First People's Hospital, Chief Technician (Nutrition), Member of the Chinese Nutrition Society, Secretary of the Youth Committee of the Xinjiang Nutrition Society

Reviewer: Yang Lin, chief physician, supervisor of Xinjiang Nutrition Society, and chief scientific communication expert of the autonomous region

At the turn of winter and spring, the climate is extremely cold and the supply of fresh vegetables is relatively scarce. Therefore, during this period, all parts of my country generally adopt pickling methods such as fish, meat, and vegetables to ensure that delicious food can be tasted even in the cold winter. The "Zhenzhou Zhuzhici Yin" in the Qing Dynasty records: "After the first snow, people pickle vegetables, called 'Hancai'... to store for winter." Pickling vegetables has a long history of thousands of years in my country. The folk pickling techniques are rich and varied, and the ingredients are wide-ranging. Almost all vegetables are pickled.

With the development of food preservation technology, modern logistics and planting technology, Xinjiang can now easily buy all kinds of fresh vegetables in winter. However, the older generation, especially the elderly in rural areas, still have a special liking for pickled vegetables, such as pickles (the main ingredients are chamagu, Jerusalem artichokes, leeks, carrots, etc.), sauerkraut (the main ingredients are Chinese cabbage and cabbage), and sweet and sour garlic (with garlic as the main ingredient). Sauerkraut tastes sour and refreshing, and pickles are salty and delicious, especially the sauerkraut noodles commonly seen in Xinjiang restaurants, which are fragrant and memorable. Every bite embodies the wisdom and enthusiasm of the working people.

1. Exploring the pickling wisdom of the older generation from a scientific perspective

From a scientific perspective, vegetables can be preserved by salting, sugaring, pickling, and adding preservatives, which are collectively referred to as chemical preservation methods. Each preservation method must follow a specific concentration ratio to achieve the goal of preserving vegetables.

01Salting and sugar pickling method:

In a highly osmotic medium, the microbial protoplasm dehydrates and shrinks, separates from the cell membrane, and coagulates, leading to the death of the microorganisms. Generally speaking, when the salting concentration reaches 10%, most bacteria will be inhibited; while sugar pickling requires a concentration of 60%-65% to ensure the effect.

02Acid pickling method:

The purpose of preservation is achieved by increasing the hydrogen ion concentration. This is used because most microorganisms cannot grow well below a pH value of 4.5, such as kimchi.

03Preservatives:

Common food preservative additives include preservatives and antioxidants. The former are used to inhibit or kill microorganisms that cause food spoilage, while the latter can be used to prevent fat rancidity.

To sum up, no matter what preservation method is used, the key is to master the appropriate concentration ratio.

2. Will it be safer if you pickle your own vegetables without preservatives?

Of course not. Although pickles are delicious, we cannot ignore the other health risks hidden in them.

First of all, we must face the impact of the high salt content in pickles. Excessive salt intake may lead to serious health problems such as high blood pressure and heart disease.

Secondly, due to the lack of professional sterile environment and operation standards, homemade pickles are more likely to produce nitrite, a potential carcinogen precursor. Experimental data show that the nitrite content of home-pickled pickles reaches its peak on the 7th day, and this finding should arouse our vigilance.

In addition, the vitamin C content in pickled vegetables is low. Long-term consumption as the main vegetable may cause vitamin C deficiency, which can easily lead to bleeding gums, dry skin, reduced immunity, etc.

Therefore, although pickles are delicious, we still need to remain rational and eat them in moderation to ensure that our health is not threatened.

3. Can pregnant women eat pickled vegetables?

Not recommended.

The storage and processing methods of vegetables have a significant impact on their nitrate and nitrite content. For example, during the pickling process, the nitrite content will increase significantly. Similarly, the nitrite content in stale vegetables will also increase significantly. Nitrite, as one of the precursor substances of N-nitroso compounds, is highly carcinogenic to animals. Its carcinogenic characteristics are as follows:

1. Can induce tumors in various experimental animals: The animals studied include rats, mice, rabbits, pigs, dogs, minks, frogs, fish, birds and primates. So far, no animal has been found to be resistant to the carcinogenic effects of N-nitroso compounds .

2. Can induce tumors in multiple tissues and organs : The main target organs of N-nitroso compounds are liver, esophagus and stomach. The main target organs of the same compound in different animals may be different, but in general, N-nitroso compounds can induce tumors in almost all tissues and organs of animals.

3. Various routes of intake can induce tumors : including respiratory inhalation, digestive tract intake, subcutaneous intramuscular injection, and even skin contact with N-nitroso compounds can cause tumors.

4. A single large dose or long-term exposure to small amounts of drugs can cause cancer : repeated administration or a single large dose can induce tumors, and there is an obvious dose-effect relationship.

5. Can cause carcinogenesis to offspring through the placenta: A large number of studies have shown that N-nitroso compounds can cause carcinogenesis to offspring through the placenta, and animals are significantly more sensitive to their carcinogenic effects during the embryonic period than after birth or during the growth period.

4. How to reduce the health risks of pickled vegetables?

01 Pickle making: Choose fresh and clean vegetables as raw materials, and avoid using rotten or diseased vegetables. During the pickling process, ensure that the container is clean to prevent bacterial contamination. The salt and seasoning used should meet food safety standards and avoid excessive addition.

02 Preservation of pickled vegetables: Food refrigeration: usually refers to low-temperature storage without freezing, with the temperature set within the range of 1°C-10°C. At this temperature, the growth and reproduction of pathogens and spoilage bacteria are inhibited, and the activity of the original enzymes in the food is reduced, thereby delaying food deterioration.

Food freezing: refers to the storage method below -18℃. At this temperature, almost all microorganisms no longer grow, and frozen food can be stored for a long time. Rapid freezing helps maintain the quality of food (especially fresh food).

03 When eating pickled vegetables: Check the state of the food: When eating pickled vegetables, you should check the state of the food. If you find any abnormal smell, color or taste, you should stop eating it immediately.

Eat in moderation: Although pickled vegetables are delicious, they contain a high salt content. Long-term excessive consumption will have adverse effects on your health.

Pay attention to the combination: When eating pickled vegetables, pay attention to the nutritional combination and eat more fresh vegetables and fruits to balance the dietary structure. Fresh vegetables and fruits are rich in vitamin C. For example, peppers, cucumbers, loofahs, winter melons, tomatoes, zucchini, kiwis, cherries, oranges, etc., which are often eaten, can provide rich antioxidants to help the body neutralize the damage of nitrosamines. Chinese scholars have also found that allicin in garlic can inhibit the activity of nitrate-reducing bacteria in the stomach, significantly reducing the nitrite content in the stomach.

Pickled vegetables, such as sauerkraut and pickles, are not only traditional Xinjiang winter delicacies, but also the crystallization of science and technology and wisdom. In this cold winter, eating pickled vegetables in moderation can enrich our dining table, but we must ensure food safety and follow the correct production methods to make delicious and healthy pickled vegetables accompany us through every warm winter day.

References:

[1] Liu Zhenzhen, Jia Qianwen, Li Tiantian, et al. Optimization of low-salt kimchi production process[J]. Chinese Condiment, 2023, 48(06): 132-137+151.

[2] Li Xiaoli, Wang Xuan. Analysis of the hazards and preventive measures of N-nitroso compounds[J]. Popular Standardization, 2021, (22): 246-248.

[3] Ren Yuanyuan, Hao Jianxiong, Wang Yunfeng, et al. Introduction to Food Safety[M]. Beijing Normal University Press: 202107.369.

[4] Sun Changhao: Nutrition and Food Hygiene (6th Edition) [M], Beijing People's Medical Publishing House: 200707.307-312.