Tetrasodium pyrophosphate is used as a pH buffer (a substance
which maintains a particular acidity level), and as a dough conditioner
in soy-based "meat alternatives". It promotes binding of proteins to
water, binding the soy particles together, and is used for the same
purpose in chicken nuggets and imitation crab and lobster products.
It is an emulsifier, and a source of phosphorus as a nutrient.
It is used in toothpastes, as a buffer, an emulsifier, and a
detergent aid. It is the "tartar control" agent. It removes
calcium and magnesium from the saliva, so they can't deposit
on the teeth.
It is a thickening agent in instant puddings.
It is a water
softener in detergents, and an emulsifier to suspend oils and
prevent them from redepositing on clothing in the wash. As a water
softener, it combines with magnesium to sequester it from the
detergent, without precipitating it onto the clothing.
As a detergent additive, it can also "reactivate" detergents or
soaps that have combined with calcium to make an insoluble scum.
The TSPP sequesters the calcium, replacing it with sodium, which
reactivates the detergent or soap, and yet keeps the calcium
from precipitating out of solution.
Because phosphates cause "eutrophication" of water (algae grows
because of the fertilizing power of phosphates), it is seldom
used as a detergent additive, except in toothpastes.
Tetrasodium pyrophosphate: InChI=1/4Na.H4O7P2/c;;;;1-8(2,3)7-9(4,5)6/h;;;;(H2,1,2,3)(H2,4,5,6)/q4*+1;/p-4/f4Na.O7P2/q4m;-4