Currently, a variety of seasonal vegetables are maturing and coming to market. However, the Hefei Municipal Agricultural Committee recently found in inspections that the pesticide residue rate in bok choy reached 20%, while the rate for 7 other samples, including cabbage, eggplant, crown daisy, and green pepper, was also 4.4%. In response, Jiang Weibo, a professor at the College of Food Science at China Agricultural University, reminded everyone to be sure to wash vegetables thoroughly before eating them.
"Many people are in the habit of soaking vegetables in water for one or two hours after buying them, thinking that the longer they soak, the cleaner the pesticides will be. In fact, this method is not scientific," Jiang explained. "When vegetables are soaked in water for a long time, residual organochlorine and organophosphate pesticides break down in the water, forming a certain concentration. The vegetable, soaking in it, will then have pesticides on its surface. This is especially true for leafy vegetables like cabbage and spinach; long-term soaking does little to remove pesticides. While salt water can help dissolve pesticides quickly and has a sterilizing effect, soaking vegetables in it for too long can be counterproductive. Some people also like to cut vegetables into small pieces before soaking, which is completely unnecessary and will only cause the vegetables to lose nutrients."
So, how should vegetables be washed correctly? Jiang said that different vegetables can be washed using different methods. For stem and gourd vegetables like cucumbers, green peppers, carrots, and bitter gourds, you can add dishwashing detergent and soak them in warm water for 1-2 minutes, then scrub them with a soft brush, paying special attention to the凹陷 areas, before rinsing with clean water. If necessary, you can also peel them.
For head vegetables like Chinese cabbage and cabbage, you can remove the outer leaves, soak the inner leaves in warm water, and then rinse them one by one under running water. For small-leafy greens like spinach, crown daisy, chickweed, and bok choy, you can cut off the roots, shake them in water to clean, and then rinse them with the roots pointing up under a faucet. The force and vibration of the water will help remove any residual pesticides.
In addition to washing, other methods can also help remove pesticide residues from vegetables. Jiang noted that leaving freshly picked vegetables in the air for 24 hours can allow some pesticide residues to break down into harmless substances, so vegetables that are not easily perishable, like winter melon, can be left to sit for a while. Furthermore, exposure to ultraviolet light can also cause some pesticide residues to break down and become inactive. For vegetables like beans and cauliflower, you can blanch them in boiling water after washing to remove any residual bacterial pesticides.