Erythorbic acid and sodium erythorbate are chemical isomers of ascorbates, they are effective antioxidants for applications that do not require a nutritional claim for vitamin activity. The efficiency of erythorbates as antioxidants depends upon the particular food system, the compounds to be protected, the amount of metal contamination, and the amount of oxygen to be removed form the system. Sodium erythorbate is not fat soluble and is most useful as antioxidant in aqueous systems. Erythorbic acid and sodium erythorbate are permitted food ingredients in the U.S. Japan and European Union.