Food Ingredients 95% Sodium Acid Pyrophosphate, SAPP 28

Disodium pyrophosphate is produced by heating sodium dihydrogen phosphate:

Disodium pyrophosphate is a popular leavening agent found in baking powders. It combines with sodium bicarbonate to release carbon dioxide:

Na₂H₂P₂O₇ + NaHCO₃ → Na₃HP₂O₇ + CO₂ + H₂O

It is available in a variety of grades that affect the speed of its action. Because the resulting phosphate residue has an off-taste, SAPP is usually used in very sweet cakes which mask the off-taste.

It is designated in the United States as generally recognized as safe (GRAS) for food use. It is used in canned seafood to maintain color and reduce purge^{[clarification needed]} during retorting. Retorting achieves microbial stability with heat. It is an acid source for reaction with baking soda to leaven baked goods. In baking powder, it is often labeled as food additive E450. In cured meats, it speeds the conversion of sodium nitrite to nitrite (NO₂) by forming the nitrous acid (HONO) intermediate,^{[clarification needed]} and can improve water-holding capacity. Disodium pyrophosphate is also found in frozen hash browns and other potato products, where it is used to keep the color of the potatoes from darkening.