Note that the direct contact area between vegetables and water increases many times after cutting vegetables, which will make water-soluble vitamins such as vitamin B, vitamin C, some minerals and some water-soluble sugars in vegetables dissolve in water and lose. At the same time, cutting vegetables will increase the chances of bacterial contamination on the surface of vegetables, leaving health risks. Therefore, vegetables should not be cut before washing, but should be washed before cutting.

1. soaking in light salt water: generally, vegetables are washed with clear water for at least 3-6 times, then soaked with light salt water and washed with clear water 1 time. Cabbage vegetables are cut first, soaked in clean water for 1~2 h, and then rinsed with clean water to remove residual pesticides.

2. Alkali washing: wash vegetables with alkali. First, put a pinch of alkali powder, anhydrous calcium carbonate or ice alkali and crystalline sodium carbonate into water, stir evenly, then add vegetables, soak for 5~6 min, pour out the alkali water, and then rinse with clear water. Baking soda can also be used instead, but it usually takes about 15 min, and the soaking time is appropriately extended.

3. Wash with detergent: dilute the detergent by 300 times 1 time, and then wash with clean water 1~2 times to remove germs, eggs and residual pesticides on vegetables.

4. Boiling water: The best way to remove some residual pesticides is scalding, such as green pepper, cauliflower, beans and celery. You'd better blanch with boiling water before cooking. According to the test, this method can remove 90% of the residual pesticides.

5. Disinfection with sunlight: Using the multi-spectral effect of sunlight to irradiate vegetables will cause some residual pesticides in vegetables to be decomposed and destroyed. According to the measurement, the residual loss of organochlorine and organomercury pesticides reached 60% when vegetables and fruits were irradiated in the sun for 5 min. For vegetables that are convenient to store, it is best to leave them for a while. Oxygen in the air and chromozyme in vegetables have a certain decomposition effect on residual pesticides. Therefore, vegetables should be stored at room temperature for about 24 h after purchase, so that the average disappearance rate of residual chemical pesticides is 5%.

6. Wash vegetables with rice: Washing vegetables with rice can remove some pesticides left in vegetables. At present, most organophosphorus pesticides used in China are methamidophos, phoxim, dichlorvos, dimethoate and so on. These pesticides will lose their toxicity when they encounter acidic substances. Soaking in rice washing water for about 10 min and washing with clear water can reduce the residual pesticide components in vegetables.