Alkaline flour, that is, edible alkali, is mainly composed of sodium carbonate, which is used to neutralize excess acidity in traditional flour dough. This process is called "alkali leaching". It can also be used to remove pesticide residues in vegetables: Because most organophosphorus pesticides can be rapidly decomposed in alkaline environment, soaking in alkaline water is one of the effective methods to remove pesticide residues in vegetables. Add 5- 10g edible alkali into 500ml clean water to make alkaline water, put the preliminarily washed vegetables into alkaline water, add enough alkaline water according to the amount of vegetables, soak for 5-10min, and then rinse the vegetables with clean water.