After vegetables are shredded, the direct contact area with water increases by many times, which will cause water-soluble vitamins such as vitamin B, vitamin C, some *minerals and some water-soluble sugars to dissolve in water and be lost. At the same time, after vegetables are shredded, the chance of being contaminated by *bacteria on the surface of vegetables also increases, leaving health隐患s. Therefore, vegetables should not be cut before washing, but should be washed before cutting.