Disodium pyrophosphate
{{Chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 443830049
| ImageFile = Disodium pyrophosphate.png
| ImageName = Disodium pyrophosphate
| IUPACName = Disodium dihydrogen diphosphate
| OtherNames = Diphosphoric acid, disodium salt
Disodium dihydrogen pyrophosphate
Disodium diphosphate
Sodium acid pyrophosphate, SAPP
|Section1={{Chembox Identifiers
| PubChem = 24451
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = H5WVD9LZUD
| ChEMBL = 3184949
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 22859
| SMILES = [Na+].[Na+].[O-]P(=O)(O)OP([O-])(=O)O
| InChI = 1/2Na.H4O7P2/c;;1-8(2,3)7-9(4,5)6/h;;(H2,1,2,3)(H2,4,5,6)/q2*+1;/p-2
| InChIKey = GYQBBRRVRKFJRG-NUQVWONBAI
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/2Na.H4O7P2/c;;1-8(2,3)7-9(4,5)6/h;;(H2,1,2,3)(H2,4,5,6)/q2*+1;/p-2
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = GYQBBRRVRKFJRG-UHFFFAOYSA-L
| CASNo = 7758-16-9
| CASNo_Ref = {{cascite|correct|CAS}}
| EINECS = 231-835-0
}}
|Section2={{Chembox Properties
| Formula = {{chem2|Na2H2P2O7}}
| Na=2|H=2|P=2|O=7
| Appearance = White odorless powder
| Density = 2.31 g/cm3
| MeltingPt = > 600 °C
| BoilingPt =
| Solubility = 11.9 g/(100 mL) (20 °C)
| RefractIndex = 1.4645 (hexahydrate)
}}
|Section3={{Chembox Structure
| CrystalStruct =
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| FlashPt = Non-flammable
| LD50 = 2650 mg/kg (mouse, oral)
}}
|Section8={{Chembox Related
| OtherAnions = {{ubl|Disodium phosphate|Pentasodium triphosphate|Sodium hexametaphosphate}}
| OtherCations = {{ubl|Calcium pyrophosphate|Dipotassium pyrophosphate}}
| OtherCompounds = Tetrasodium pyrophosphate
}}
}}
Disodium pyrophosphate or sodium acid pyrophosphate (SAPP){{cite web|url=http://www.lallemand.com/BakerYeastNA/eng/PDFs/LBU%20PDF%20FILES/1_12CHEM.PDF|title=Lallemand Baking Update: Chemical Leaveners Volume 1 / Number 12 |author= |date=1996 |website=www.lallemand.com |publisher=Lallemand Inc. |accessdate=6 January 2018}} is an inorganic compound with the chemical formula {{chem2|Na2H2P2O7|auto=1}}. It consists of sodium cations ({{chem2|Na+}}) and dihydrogen pyrophosphate anions ({{chem2|H2P2O7(2−)}}). 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. {{chem2|Ca(2+)}}.
Disodium pyrophosphate is produced by heating sodium dihydrogen phosphate:
:{{chem2|2 NaH2PO4 → Na2H2P2O7 + H2O}}
Food uses
Disodium pyrophosphate is a popular leavening agent found in baking powders. It combines with sodium bicarbonate to release carbon dioxide:
:{{chem2|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.John Brodie, John Godber "Bakery Processes, Chemical Leavening Agents" in Kirk-Othmer Encyclopedia of Chemical Technology 2001, John Wiley & Sons. {{doi|10.1002/0471238961.0308051303082114.a01.pub2}}
File:Tin, food product (AM 2015.4.24-2).jpg
Disodium pyrophosphate and other sodium and potassium polyphosphates are widely used in food processing; in the E number scheme, they are collectively designated as E450, with the disodium form designated as E450(a). In the United States, it is classified as generally recognized as safe (GRAS) for food use. In canned seafood, it is used to maintain color and reduce purge{{Clarify|date=January 2010}} during retorting. Retorting achieves microbial stability with heat.http://www.foodproductdesign.com/articles/1994/08/in-the-can.aspx -Retorting, Accessed 2010-11-27 It is an acid source for reaction with baking soda to leaven baked goods.{{cite book | author = Ellinger, R.H. | year = 1972 | chapter = Phosphates in Food Processing | title = Handbook of Food Additives | edition = 2nd | publisher = CRC Press | location = Cleveland | pages = 617–780}} In baking powder, it is often labeled as food additive E450.{{Cite web|url=http://www.food-info.net/uk/e/e450.htm|title = Food-Info.net : E-numbers : E450 Potassium and sodium di-phosphates}} In cured meats, it speeds the conversion of sodium nitrite to nitrite ({{chem2|NO2−}}) by forming the nitrous acid (HONO) intermediate,{{clarify|reason=Conversion of sodium nitrite to nitrite?|date=December 2013}} 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.
Disodium pyrophosphate can leave a slightly bitter aftertaste in some products, but "the
SAPP taste can be masked by using sufficient baking soda and by adding a source of calcium ions, sugar, or flavorings."
Other uses
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|date=May 2014}} It is used in cat foods as a palatability additive.{{cite magazine |last=Roach |first=Mary |date=2013-03-25 |title=The Chemistry of Kibble |url=http://www.popsci.com/science/article/2013-03/chemistry-kibble |magazine=Popular Science |quote=Pyrophosphates have been described to me as "cat crack." Coat some kibble with it, and the pet food manufacturer can make up for a whole host of gustatory shortcomings. |access-date=2016-02-16}}
Disodium pyrophosphate is used as a tartar control agent in toothpastes.
References
External links
- {{Commons category-inline}}
{{Phosphates}}