Sodium benzoate is a commonly used food preservative in China's food industry. It has a sweet and astringent smell, is stable in the air, and can absorb moisture when exposed in the air. It naturally exists in blueberries, apples, plums, cranberries, prunes, cinnamon and cloves. Its bactericidal performance is weaker than benzoic acid. In acidic environment, sodium benzoate has obvious inhibitory effect on a variety of microorganisms. When pH is 3.5, 0.05% solution can completely inhibit the growth of yeast, but when pH is above 5.5, it has poor effect on many molds and yeasts. It has little effect in alkaline solution. In the process of biotransformation, sodium benzoate combines with glycine to form uric acid, or combines with glucuronic acid to form glucosidic acid, and all of them are excreted from the urine. In the normal dosage range, it has no toxic effect on human body and is a safe preservative. It can be used for carbonated drinks, concentrated fruit juice, margarine, gum base, jam, jelly, soy sauce, etc.