Trisodium phosphate

Trisodium phosphate (CAS 7601-54-9), abbreviated TSP and approved as food additive E339iii, is an inorganic phosphate salt used for pH control and sequestration. Also known as tribasic sodium phosphate.

Where is Trisodium phosphate used?

• Industrial cleaning: heavy-duty degreaser for metal and concrete surfaces
• Food and beverage: buffering and sequestering agent in processed cheeses, cured meats and cereal products
• Water treatment: adjusts pH and inhibits scale in boiler and cooling water systems
• Textile and paper processing: scouring aid and flame-retardant formulation aid
• It controls acidity and binds metal ions that would otherwise accelerate spoilage.
• In processed meat and seafood, acts as a pH regulator and moisture retainer, improving water retention by about 15% in poultry.
• In instant noodles, optimizes starch gelatinization, reducing breakage during frying by 30–40% compared to phosphate-free formulations.
• Used for surface preparation before painting.
• Breaks the gloss of oil-based paints and opens the pores of latex-based paint to provide a more suitable surface for the next coat to adhere.

Good to know: Anhydrous and dodecahydrate forms are both commercially available. Food-grade material meets purity thresholds required for direct food contact applications.

Formulation notes

• For each 1 m³ of make-up water with a hardness of 0.18 mol/m³ (1°dH), 68 grams are added.
• A 2023 study found that cheeses with 0.3% trisodium phosphate retained 92% of emulsified fat during cooking, compared to 78% in untreated samples.
• A 3-5% solution (3-5 kg per 100 L) is prepared in a dosing container for water treatment.
• Clean label trends are driving manufacturers to replace trisodium phosphate in cereal coatings and snack products with alternatives such as fermented dextrose or rice starch.

Typical specification

• Dodecahydrate is available in a food-grade, pure form with a purity of 98% or higher.
• Moderately soluble in water, with a solubility of 14 g/100 ml at 25°C.
• Available in technical grade.

Regulatory status

• Registered under the REACH Regulation and manufactured and/or imported in the European Economic Area at 10,000 to 100,000 tonnes per year.
• EFSA and Codex Alimentarius permit trisodium phosphate with specific limits ranging from about 0.3% in processed cheeses to 0.5% in various meat products.
• EFSA has set an acceptable daily intake of 70 mg/kg body weight.
• Use in detergents is now banned in some countries, including Switzerland.

Storage, packaging and handling

• Should be stored in a cool, dry, well-ventilated place, away from sunlight and incompatible substances such as strong acids.

Frequently asked questions about Trisodium phosphate

How does trisodium phosphate function in seafood during freezing?

It prevents protein degradation during freezing in seafood, keeping shrimp firm and fish fillets intact after thawing.

What role does trisodium phosphate play in processed cheese melting?

It enables uniform melting in processed cheese by chelating calcium ions that cause graininess.

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