Sodium benzoate is an acidic preservative, which has no bactericidal or bacteriostatic effect in alkaline medium; its best antiseptic pH is 2.5-4.0, and the bactericidal effect of a 5% solution at pH 5.0 is not very good. Sodium benzoate has high lipophilicity, easily penetrates the cell membrane and enters the cell body, interferes with the permeability of the cell membrane, and inhibits the absorption of amino acids by the cell membrane; it enters the cell body to ionize and acidify the alkali storage in the cell, and inhibit the activity of the respiratory enzyme system of the cell. Prevent the condensation reaction of acetyl-CoA, so as to achieve the purpose of food preservation