Monosodium phosphate

Monosodium phosphate (CAS 7558-80-7), abbreviated MSP and designated E339i in food applications, is an inorganic phosphate salt. Also known as sodium phosphate monobasic.

Where is Monosodium phosphate used?

• Water treatment: controls scale and corrosion in boiler and cooling systems by sequestering calcium and magnesium ions
• In water treatment, acts as a corrosion controller, and when paired with polyphosphates it obstructs scale formation.
• Food: buffering and emulsifying agent in processed cheeses, cured meats and beverage formulations
• In food, used as a leavening agent.
• Pharmaceuticals: buffer solutions for parenteral formulations, oral dosage forms and laxative preparations
• Fermentation media: nutrient source supporting microbial growth
• It buffers pH and sequesters metal ions.
• Often mixed with another solution, for example one containing potassium dihydrogen phosphate, to make a Sörensen buffer.

Good to know: Anhydrous and hydrated versions serve distinct formulation requirements. Food and pharmaceutical grades meet purity specifications.

Typical specification

• Monobasic Sodium Phosphate contains not less than 98.0% and not more than 103.0% of monobasic sodium phosphate (NaH2PO4), calculated on the anhydrous basis.
• Often comes in crystal and powder forms.
• Available in a dihydrate form containing water in its structure, suitable for processes where moisture is critical.

Regulatory status

• The safety of monosodium phosphate was re-evaluated by EFSA in 2019, establishing an acceptable daily intake (ADI) of 40 mg/kg body weight expressed as phosphorus.
• Due to adverse kidney reactions, sodium and phosphorus-based laxatives have been discontinued in some countries.

Frequently asked questions about Monosodium phosphate

In which food applications is monosodium phosphate used as an acid component?

It is used as an acid component in dry powdered soft drinks, effervescent powders, and lactasites.

What function does monosodium phosphate serve in instant puddings?

It is used as a gelling accelerator in instant puddings to preserve egg yolk color before cooling.

What is the role of monosodium phosphate in dried meats?

In dried meats, it is used as a curing salt and sequesters water to maintain moisture while deterring spoilage.

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