Disodium pyrophosphate (CAS 7758-16-9)

Disodium pyrophosphate or sodium acid pyrophosphate (SAPP) is an inorganic compound consisting of sodium cations and pyrophosphate anion. It is a white, water-soluble solid that serves as a buffering and chelating agent, with many applications in the food industry. When crystallized from water, it forms a hexahydrate, but it dehydrates above room temperature. Pyrophosphate is a polyvalent anion with a high affinity for polyvalent cations, e.g. Ca2+.

In leather treatment, it can be used to remove iron stains on hides during processing. It can stabilize hydrogen peroxide solutions against reduction. It can be used with sulfamic acid in some dairy applications for cleaning, especially to remove soapstone. When added to scalding water, it facilitates removal of hair and scurf in hog slaughter and feathers and scurf in poultry slaughter. In petroleum production, it can be used as a dispersant in oil well drilling muds.[citation needed] It is used in cat foods as a palatability additive.[6] Disodium pyrophosphate is used as a tartar control agent in toothpastes.