Many people like to soak vegetables for a period of time when washing them, thinking that this makes them cleaner and safer to eat. In fact, soaking vegetables for a long time before washing does not necessarily remove more pesticide residues and may even increase the formation of carcinogenic nitrites.
First, soaking is not more effective for removing pesticide residues. Dai Yunqing, an associate professor at the College of Food Science at China Agricultural University, pointed out that the main component of pesticide residues is organophosphorus, which is not water-soluble. In contrast, soaking with tap water and dishwashing detergent followed by rinsing is more effective at removing pesticides.
Second, soaking vegetables for a long time also increases their nitrite content. After soaking in clean water for 20 minutes, the nitrite content in vegetables is higher than in vegetables washed with dishwashing detergent and then thoroughly rinsed. Research suggests this may be because soaking creates an anaerobic condition, which helps increase the activity of nitrate reductase and decrease the activity of nitrite reductase, thereby increasing the nitrite content in the vegetables. Finally, prolonged soaking can also damage the vegetable leaves, leading to greater nutrient loss.
Therefore, when washing vegetables, it is crucial to control nitrite levels. It is best to rinse vegetables under running water 3 to 4 times, and soaking should be avoided as much as possible. If soaking is necessary, the time should not exceed 20 minutes. When preparing cold dishes with vegetables, adding minced garlic and lemon juice can help reduce the risk of nitrite poisoning.