Introduction: With the advent of autumn and winter, cabbage and radish have become one of the most popular vegetables in the market, and the ** in this season is relatively cheap, and the storage method is very simple, so they have become a must-have on the table of many families.
At every vegetable stall, we can see a large number of cabbage, but what problems do we need to pay attention to when choosing these cabbage?In particular, how can we avoid buying cabbage that contains formaldehyde?
Some netizens raised a question, how can cabbage, as such a cheap vegetable, be sprayed with formaldehyde?Most people are skeptical when they hear the news, thinking it's impossible.
However, there are also some people who believe this rumor, thinking that some unscrupulous merchants will choose to spray formaldehyde in order to maintain the freshness of cabbage, is this rumor true or false?
Cabbage, a seemingly ordinary vegetable, contains rich nutrition and unique deliciousness, and it has become one of the indispensable delicacies on many people's tables, known as the "king of 100 vegetables".
The taste of cabbage is delicious, crisp and refreshing, whether it is fried, stewed, boiled or cold, it can show its unique charm, and cabbage is also rich in nutrients, the nutrients per 100 grams of cabbage are as follows:
Moisture: 95 grams;
Protein: 15 grams;
Calcium: 90 mg;
Carbohydrates: 29 grams;
Dietary fiber: 12 grams;
Fat: 03 grams;
Vitamin A: 287 mcg;
Vitamin C: 38 mg;
Iron: 05 mg.
Promotes digestion
Cabbage is rich in fiber, which helps to promote intestinal peristalsis and improve digestive function, which is undoubtedly a great boon for those with indigestion or constipation.
Antioxidant
The antioxidants in cabbage, such as vitamin C and selenium, help to scavenge free radicals in the body and prevent cells from oxidative damage, thereby delaying aging.
Boosts immunity
The many vitamins and minerals in cabbage, such as vitamin A, vitamin E, and zinc, help to strengthen immunity, improve the body's resistance, and reduce the occurrence of diseases.
Protects the cardiovascular system
The folic acid in cabbage helps reduce homocysteine levels in the blood, which reduces the risk of cardiovascular disease. In addition, the dietary fiber in cabbage also helps lower cholesterol and further protects cardiovascular health.
Anti-inflammatory
Certain compounds in bok choy have anti-inflammatory effects and help alleviate inflammatory diseases such as arthritis and gastritis, among others.
Formaldehyde is a common indoor air pollutant, mainly released from formaldehyde in building materials such as decoration and furniture, and it is one of the carcinogens assessed by the World Health Organization, which will cause harm to the human body.
Formaldehyde is a colorless, pungent odor gas, the chemical formula is HCO or CHO, at room temperature, formaldehyde can exist in gaseous form, and can be soluble in water, formaldehyde is not easy to decompose at room temperature, so it can exist in indoor air for a long time.
The harm of formaldehyde is mainly manifested in the following aspects:
1.Stimulation:Formaldehyde will have an irritating effect on ** and mucous membranes, causing people to have symptoms such as tearing, coughing, and sore throat.
2.Sensitization:Formaldehyde is also easy to cause allergies, erythema, itching and other symptoms.
3.Carcinogenicity:Long-term exposure to formaldehyde increases the risk of cancers such as lung, nasopharyngeal, and leukemia.
Formaldehyde cabbage, as the name suggests, refers to the cabbage sprayed with formaldehyde solution on the cabbage, formaldehyde is a common chemical substance, which has the effect of antiseptic and disinfection.
In hospitals, the commonly used solution is a formaldehyde aqueous solution with a concentration of 35% to 40%, which is used to preserve organs and tissues, and in agriculture, formaldehyde is also often used as a soaking disinfectant, with a concentration of 01% to 05%。
However, this functional attribute of formaldehyde is not suitable for the preservation and preservation of fruits and vegetables, driven by economic interests, some unscrupulous businesses began to use the method of spraying formaldehyde to keep cabbage fresh.
They believe that this can prevent the cabbage from spoiling during transportation, and the cabbage after spraying formaldehyde has white roots and excellent appearance, which is easier to attract consumers.
However, this practice is extremely dangerous, formaldehyde is a toxic substance, long-term consumption of food containing formaldehyde may cause harm to the human body, and even cause cancer, therefore, consumers must pay attention to check whether it contains formaldehyde when buying cabbage.
Cabbage that looks very bright
In the process of buying vegetables, we all want to choose the freshest and highest quality ingredients, however, sometimes too bright colors may cause us to be alarmed, because some merchants may use some improper means to extend the shelf life and improve the appearance of vegetables. Taking cabbage as an example, when we see cabbage with particularly bright colors, we may think that it is a high-quality product, however, in fact, some merchants will spray formaldehyde in order to keep cabbage fresh. After spraying formaldehyde, the color of the cabbage will become particularly bright and it will remain for a longer time, however, this brightness does not represent the freshness and quality of the cabbage. On the contrary, it may mask the improper tactics used by merchants in pursuit of appearance. 
The smell is pungent
In the process of buying cabbage, the sense of smell is a very important sense, and before picking a cabbage, it is first necessary to judge its freshness and quality by smelling the taste of the cabbage.
High-quality fresh cabbage, which should smell like a fresh, natural vegetable, without any other peculiar smells. This natural smell is unique to the cabbage itself, and it is reassuring.
However, if you smell a pungent smell when buying cabbage, you need to be more vigilant, and this pungent smell is most likely caused by chemicals such as formaldehyde spraying onto the surface of the cabbage. 
There is rot in the roots of cabbage
Cabbage sprayed with formaldehyde usually has a significant feature, that is, their roots are prone to rot, which may be due to the formaldehyde solution penetrating into the cabbage, causing damage to the tissues of the cabbage, causing the roots to gradually become soft, black, and eventually rot. In cabbage sprayed with formaldehyde, rot usually occurs in the part where the roots come into contact with the soil, because the formaldehyde solution is more likely to penetrate into the roots of the cabbage and destroy its cell structure.
This prevents the cabbage from absorbing water and nutrients properly, and over time, this damage gradually worsens, eventually leading to rot of the cabbage roots.
Increased risk of cancer
Formaldehyde is assessed by the World Health Organization as one of the carcinogens, and long-term intake of vegetables containing formaldehyde, especially leafy vegetables, will increase the risk of cancer, especially nasopharyngeal cancer and esophageal cancer.
A compromised immune system
Formaldehyde has a toxic effect on the immune system, and long-term intake can lead to a decrease in immune function, making people more susceptible to diseases.
Liver damage
Formaldehyde is mainly metabolized and excreted in the body through the liver, and long-term intake of vegetables containing formaldehyde will cause damage to the liver, which may lead to hepatocyte degeneration, necrosis and cirrhosis.
Neurotoxicity
Formaldehyde has a toxic effect on the nervous system, and long-term ingestion may cause symptoms such as memory loss, difficulty concentrating, headache, and dizziness.
Observe the color and appearance of the cabbage
Fresh cabbage should be bright green with a smooth surface with no visible spots or breakage, if the cabbage is dull in color or has significant breakage on the surface, then it may not be fresh anymore.
Smell the cabbage
Fresh cabbage should have a refreshing taste with no odor or foul smell, and if the cabbage smells foul or foul, then it may have gone bad.
Pick a well-sized cabbage
Moderately sized cabbage is generally easier to preserve and cook, too large may be too old and hard, and too small may not be ripe enough.