Sorbic Acid can restrain effectively the activity of mould, yeast and aerophile bacteria. Restrain growth and reproduction of the pernicious micro organism as pseudomonas, staphylococcus salmonella action to restrain growth is more powerful than killing. Meanwhile, it can not restrain useful microorganism growth as Anaerobic spore-bearing bacilli, acidophil therefore to lengthen food store period and remain food original flavor. The preservative efficiency of sorbic acid is 5-10 times sodium benzoate.