Some vegetables contain substances that affect human health, which are a type of "toxin" that needs to be removed.
Oxalic Acid
For example, spinach, bamboo shoots, green garlic, onions, water bamboo, and edamame all contain a relatively high amount of oxalic acid. Besides its astringent taste, oxalic acid can bind with calcium ions in food to form insoluble calcium oxalate, preventing the calcium in the food from being absorbed and utilized by the body. At the same time, oxalates also hinder the absorption of iron from food. Long-term consumption of vegetables high in oxalic acid can not only lead to calcium deficiency and anemia but may also cause kidney stones. If these vegetables are cooked with tofu, eggs, or animal liver, the calcium and iron in these foods will form insoluble calcium and iron salts, which cannot be absorbed by the human body. Tip: It's best to blanch these vegetables in boiling water before stir-frying to remove most of the oxalic acid.
Inherent Toxic Substances
In addition, some vegetables contain toxic substances that can cause food poisoning. For instance, beans like kidney beans and green beans contain toxins such as phytohemagglutinin and saponins. When not cooked thoroughly, these toxins remain active. Symptoms usually appear 1 to 5 hours after consumption and include sudden onset of nausea, vomiting, abdominal pain, diarrhea, as well as dizziness, headache, cold sweats, and general weakness.
Reminder: When cooking beans, ensure they are discolored and have no raw bean smell before eating. Do not eat beans that are hard in texture and have a strong bean smell. In canteens at construction sites, workplaces, and at home, beans must be cooked thoroughly. For dishes like braised or stewed beans, ensure they are well-cooked. For stir-fried or cold dishes with beans, they must be blanched and cooked thoroughly.
Pesticides, Fertilizers, etc.
During the vegetable growing process, due to various factors such as soil, fertilizers, and pesticides, nitrates, pesticide residues, parasite eggs, and various bacteria can contaminate vegetables. Therefore, on one hand, one should not blindly follow the trend of eating raw vegetables. On the other hand, these problems are not difficult to solve and are not a reason to be so terrified of "toxins" that you stop eating vegetables altogether. By understanding the nature of vegetables, buying fresh ones, washing them carefully before cooking, and cooking them thoroughly, you can ensure "toxic" vegetables stay away from you and health follows you. Tips for Removing Pesticides from Vegetables:
Since pesticides are mainly attached to the surface of fruits and vegetables during application, effective washing and processing methods can reduce pesticide residues and ensure the safety of the vegetables.
Soaking and scrubbing with clean water can reduce pesticide residues, and the longer the soaking time, the fewer the residues. Experiments have shown that soaking vegetables in tap water for 10-60 minutes followed by light scrubbing can remove 15%-60% of pesticide residues. Using a special fruit and vegetable detergent for soaking is more effective at reducing pesticide adhesion. Diluting the detergent at a ratio of 1:200 with water and soaking fruits and vegetables for 10-60 minutes can reduce pesticide residues by 50%-80%. Especially in the first 10 minutes of soaking, the reduction in pesticide residues is very significant, reaching about 50%. Then, after light scrubbing, rinsing with clean water can basically remove the pesticide residues.
High-temperature heating can also decompose pesticides, such as blanching in boiling water or stir-frying in oil. Experiments have shown that for some heat-resistant vegetables like cauliflower, beans, green peppers, and celery, washing them and then blanching in boiling water for a few minutes can reduce pesticide residues by about 30%. Subsequent high-temperature stir-frying can remove 90% of the pesticides on the vegetables.
In addition, washing vegetables with rice water and appropriate exposure to sunlight can also help reduce pesticide residues. It's best to use the first or second batch of rice water, as the surface of the rice contains potassium, making the initial batches of rice water weakly acidic. After that, it becomes alkaline, and pesticides only lose their toxicity in acidic substances. Sunlight exposure can decompose and destroy some pesticides on vegetables. According to measurements, exposing vegetables to sunlight for 5 minutes can reduce the residues of organochlorine and organomercury pesticides by about 60%.
Peeling vegetables can also reduce pesticide residues, but it leads to a loss of vitamins and minerals in the peel. Therefore, the best way to remove pesticides is to first soak fresh fruits and vegetables in a detergent for 10-15 minutes, or in tap water for 30-60 minutes, and then rinse them thoroughly with clean water.