Only two chemical preservatives permitted by FPO are

Only two chemical preservatives permitted by FPO are Sodium benzoate and Potassium meta-bisulphate.
Sodium benzoate is best known as a preservative used in processed foods and beverages to extend shelf life. It is an odorless, crystalline powder made by combining benzoic acid and sodium hydroxide.
Potassium metabisulfite, K₂S₂O₅, also known as potassium pyrosulfite, is a white crystalline powder with a pungent odour. It is mainly used as an antioxidant or chemical sterilant.