A polyphosphate is formed by a number of simple phosphate units linked together, and sodium tripolyphosphate contains three such units.
The brief manufacturing processes are as follows (1) :
STPP is commercially produced by the neutralization of phosphoric acid with sodium hydroxide to form the mixture of monosodium phosphate and disodium phosphate.
Then heat the mixture to 500-550 °C. Here is the reaction equation: NaH2PO4 + 2Na2HPO4 → Na5P3O10 + 2H2O
Food grade STPP exists as two forms, and follows the corresponding chemical formula:
STPP Anhydrous: Na5O10P3
STPP Hexahydrate: Na5O10P3 · 6H2O
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| CAS number | 7758-29-4 |
| Appearance | White powder or granular powder |
| Solubility | Soluble in water, insoluble in ethanol |
| PH | 9.1 to 10.2 (1 % solution) |
With the capability of maintaining water, the primary uses of food grade sodium tripolyphosphate are to improve the eating quality in food processing, especially in meat and fish products. It is also applied in pet food (e.g. cat and dog food) for the purpose of binding water and keeping the animal feed fresh.
It may also be used as a food starch modifier.
With the functions of chelating metal ions, suspending, dispersing, emulsifying, pH buffering, and etc, technical grade STPP is widely used in the production of laundry detergents & dishwashing detergents, industrial water softener, industrial cleaner, a grease remover, leather pre-tanning agent, dyeing auxiliary agent and so on.