Sodium Acid Pyrophosphate (SAPP).

White powder or granular; Relative density 1.86g/cm3; Soluble in water and insoluble in ethanol; If its aqueous solution is heated together with diluted inorganic acid, it will be hydrolyzed into Phosphoric Acid; It is hygroscopic, and when absorbing humidity it will become into a product with hexahydrate; If it is heated at a temperature above 220℃, it will be decomposed into sodium metaphosphate.

As a leavening agent it is applied to roast foodstuffs to control the fermentation speed; When applied to instant noodles, it can shorten water resetting time and avoid stickiness and mushiness of the noodles; When applied to crackers or cakes, it may shorten fermentation time, lower the breakage, make the porous space in good order and therefore lengthen the shelf life.