Vegetables are prone to produce nitrite. Such as Chinese toon, spinach, celery and other green leafy vegetables. . I suggest buying vegetables now. Nitrite can react with amine, an intermediate metabolite in protein, to produce nitrosamine, a carcinogen. Long-term small intake may also be harmful to health. Because nitrite is easily soluble in water, more than 70% of nitrate and nitrite can be removed by boiling water, and green leafy vegetables can be cooked for 5 ~ 10 second.
Vegetables containing natural toxins. Such as kidney beans, lentils, long beans, fresh daylily, etc. It is suggested to remove the tips and filaments at both ends of beans, soak them in water for 5 minutes, and then blanch them in boiling water for 5 minutes to make them lose their original green color. In addition, colchicine contained in fresh day lily is also easy to cause poisoning. It is recommended to cook for 5 minutes before cooking.
Vegetables that are not easy to clean. Such as broccoli and cauliflower. These vegetables are not easy to wash or peel, and boiling water can better remove pesticide residues. Organophosphorus pesticides and carbamate pesticides commonly used in China have thermal instability, and the degradation rate increases with the increase of temperature. It is suggested to boil water 1 ~ 2 minutes before cooking, and the time should not be too long, so as not to destroy the anticancer component isothiocyanate.
Meat. Different meats have different blanching methods. Fish and shrimp are suggested to be blanched with boiling water 1 ~ 2 minutes, and then marinated with salt, cooking wine, etc. This will not only help to remove the fishy smell, but also keep the fresh taste of fish and shrimp, so that the fish will be more complete when stewed.
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In order to maintain the color of vegetables, or to remove off-flavor, astringency and oxalic acid, some vegetables must be blanched before cooking. But from a nutritional point of view, blanching will increase the loss of water-soluble nutrients. When Chinese cabbage was scalded in 100℃ water for two minutes, the loss rate of vitamin C reached 65%. After scalding for more than 10 minutes, vitamin C is almost lost. Therefore, appropriate methods should be adopted to minimize the loss of nutrients.
Try to keep the vegetables intact before blanching and reduce the contact area between heat and water. In the case of more raw materials, it is necessary to feed them in batches to ensure that the raw materials are at a higher water temperature.
After blanching, the temperature of vegetables is relatively high, and after leaving water, they contact with oxygen in the air to produce hot oxygen, which is the continuation of nutrient loss. Therefore, vegetables after blanching should be cooled in time. The common method is to use a lot of cold water or cold air to cool down and dissipate heat. The former, because vegetables are put in water, soluble nutrients are lost due to the action of water; The latter is better because there is no such factor.
CCTV-Which ingredients need to be blanched before cooking?
Baidu Encyclopedia-Longshui