Citric acid is a mild natural acid found in many living things but highest in Citrus fruits, hence the name. It is a great antioxidant and can be used as a mild preservative. It is also a natural chelating agent and is used in Shampoo to draw out minerals like Chlorine from hair. It can also be used in combination with Bicarbobate of Soda (Baking soda) in products like bath bombs to create gentle carbonation. It is also used to rectify the pH during manufacture and for finished products.