Sodium Phosphate

In chemistry, a salt is a compound that forms when an acid and base react to neutralize one another.  Sodium phosphate is a term used to describe the various salts of sodium and phosphate.

Trisodium phosphate hydrate.jpg
Trisodium phosphate hydrate“. Licensed under Public domain via Wikimedia Commons.


Sodium phosphate is used for a lot of different purposes. In food, they can:

  • act as a leavening agent in baked goods
  • control the even melt of processed cheese
  • control the pH of foods
  • modify textures
  • act as an emulsifier
  • change the surface tension in liquids (such as evaporated milk)

Sodium phosphates are added to food all over the world. They are approved food additives in Canada1, the USA2, Europe3 and Australia4.


Sodium phosphates are made from mined phosphate rock.  The rock is crushed and mixed with sulfuric acid.  Phosphoric acid is then extracted from the mixture.  To produce food grade phosphoric acid, arsenic, fluorine and other impurities are removed.  Finally, the acid is combined with a sodium base.

Sodium phosphates are common food additives.  They are also used in water treatment, soaps and other cleaning products, and as a flux used when soldering medical grade copper.

Common Uses:

Some specific examples of sodium phosphates in food include:

Health Issues / Side Effects:

Sodium phosphates are commonly used as food additives because they are cheap and have no related side effects.

They may sometimes be used in medicine to relieve constipation or in enemas prior to surgery.  In these cases, some people might develop kidney problems5.  Many oral sodium phosphate drugs have been discontinued in the United States6.


Sodium phosphates have an E Number of 339.  They are classified as emulsifiers and acidity regulators.


  1. Canadian List of Permitted Food Additives
  2. FDA Food Additives Status List
  3. Current EU Approved Food Additives
  4. Australia New Zealand Food Standards Code
  5. Acute phosphate nephropathy
  6. MedlinePlus

Further Reading

Applications and Functions of Food-grade Phosphates – Wiley Online Library

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