Sodium tripolyphosphate

Sodium tripolyphosphate (CAS 7758-29-4), commonly known as STPP or E451i, is a polyphosphate salt used in detergent manufacturing, food processing, and industrial treatment.

Where is Sodium tripolyphosphate used?

• Detergent and cleaning products: builder that softens water by sequestering hardness ions, boosting surfactant performance in household and industrial cleaners
• Food: moisture-retention and texture agent in processed meats, seafood, and dairy products
• Water treatment: controls scale formation and disperses mineral deposits in industrial cooling and boiler systems
• Ceramics and paper: deflocculant that reduces slurry viscosity and improves material processability
• It binds calcium and magnesium ions as a sequestrant, builder, and dispersing agent.
• In meat products, increases water holding capacity by sequestering calcium and magnesium ions.

Typical specification

• Freely soluble in water and insoluble in organic solvents.

Regulatory status

• Maximum permitted dose in processed cheese and similar products is 20 g/kg expressed as P2O5.
• Maximum permitted dose in sterilized and UHT milk is 1 g/L expressed as P2O5.
• Maximum permitted dose in sports drinks and prepared table waters is 0.5 g/L expressed as P2O5.
• Considered a technological coadjuvant and food additive under EU Regulation 1333/2008.
• Purity specifications for E 451 i (sodium tripolyphosphate) are aligned with the JECFA (FAO/WHO) Codex Alimentarius standards.

Storage, packaging and handling

• Slightly hygroscopic and can cause caking if not stored properly.
• Store in a dry, cool place with the container closed.

Frequently asked questions about Sodium tripolyphosphate

How does STPP interact with proteins in meat processing?

In food, STPP extracts actinin and myosin proteins during maturation and fermentation, which then bind the product upon cooking or drying.

What are the typical specifications for tripolyphosphate content and pH?

Tripolyphosphate content as Na5P3O10 is 94% with a tolerance of +/-0.5%, and the pH of a 1% aqueous solution is 9.5 with a tolerance of +/-0.5%.

What forms and grades of STPP are available?

STPP exists in anhydrous and hexahydrate forms, and technical grade is used for detergents and ceramics.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.