Sodium acid pyrophosphate (SAPP), or disodium pyrophosphate, is a condensed phosphate formed when sodium orthophosphate is heated to remove the water. It is an inorganic compound consisting of sodium cations and pyrophosphate anion. It is used in food mainly for its two properties: It is a leavening acid that combines with baking soda to release carbon dioxide to improve the texture and volume of baked goods. It is a chelating agent to chelate iron to prevent discolouration in processed potatoes. It is extensively used in food processing, such as in canned seafood, cured meat, and potato products, to adjust the pH, maintain colour, improve the water-holding capacity, and reduce purge during retorting. However, little is known about its toxicity[1].
Disodium dihydrogendiphosphate [7758-16-9], disodium diphosphate, acidic sodium pyrophosphate, Na2H2P2O7, Mr 221.97, d 2.31. Its solubility in water is 13g Na2H2P2O7/100g H2O at 20 °C, and 20g at 80°C. The pH of a 1% aqueous solution is 4.1. The usual commercial product is the anhydrous, nonhygroscopic salt in powder form. The hexahydrate, Na2H2P2O7.6H2O, d 1.85, crystallizes from aqueous solution below 27 °C. Above this temperature, it is converted to the anhydrous form. Disodium diphosphate is used as a (tropically stable) acid carrier in baking powder, for improvement of flow properties in flour, for pH regulation, and in dental care products for prevention of tartar formation.
Sodium Pyrophosphate Dibasic is anhydrous form, pyrophosphate salt used in buffers.
Sodium Pyrophosphate is a leavening agent, preservative, sequestrant, and buffer which is mildly acidic with a ph of 4.1. It is moderately soluble in water, with a solubility of 15 g in 100 ml at 25°c. It is used in doughnuts and biscuits for its variable gas release rate during the mixing, bench action, and baking process. It is used in baking powder as a leavening agent. It is used in canned fish products to reduce the level of undesired struvite crystals (magnesium ammonium phosphate hexahydrate) by complexing the magnesium. It is used to sequester metals in processed potatoes. It is also termed sapp, sodium acid pyrophosphate, acid sodium pyrophosphate, disodium diphosphate, and disodium dihydrogen pyrophosphate.
Disodium dihydrogendiphosphate is produced from sodium dihydrogenmonophosphate by heating at 200-250℃：
Na2CO3+2H3PO4→2NaH2PO4+H2O+CO2↑
2NaH2PO4→Na2H2P2O7+H2O
The APP (amyloid precursor protein) gene is mapped to human chromosome 21q21.3. It encodes a integral membrane protein. APPα is a soluble protein generated by sequential cleavage with α and γ secretase.
Flammability and Explosibility
Non flammable
Amyloid precursor protein α is an α-secretase-cleaved soluble protein that has been shown to have neuroprotective properties. It is derived from amyloid precursor protein. The protein consists of 612 amino acids. Several G protein-coupled receptors are known to activate α-secretase-dependent processing of APP. It has neuroprotective, neurogenic and neurotrophic functions. Amyloid precursor protein a also stimulates gene expression and protein expression.
Poison by intravenous
route. Moderately toxic by ingestion and
subcutaneous routes. An irritant to skin,
eyes, and mucous membranes. When heated
to decomposition it emits toxic fumes of
POx, and Na2O.
[1] Yasmina M. Abd-Elhakim . “Effects of the food additives sodium acid pyrophosphate, sodium acetate, and citric acid on hemato-immunological pathological biomarkers in rats: Relation to PPAR-α, PPAR-γ and tnfα signaling pathway.” Environmental toxicology and pharmacology 62 (2018): Pages 98-106.
