E451(i) – Pentasodium triphosphate

General Information

Additive E451(i) — pentasodium triphosphate is a subtype of the food additive E451, belonging to the group of polyphosphates. Other common names include sodium tripolyphosphate, STPP (from English Sodium Tripolyphosphate). The chemical formula is Na₅P₃O₁₀.

Industrial production of sodium tripolyphosphate is based on the reaction of sodium dihydrogen phosphate (NaH₂PO₄) and disodium hydrogen phosphate (Na₂HPO₄) followed by dehydration at about 450 °C:

2NaH₂PO₄ + 3Na₂HPO₄ → Na₅P₃O₁₀ + 4H₂O

Sodium tripolyphosphate is a white crystalline powder, highly soluble in water. It has a strong ability to bind calcium and magnesium ions, which softens water and stabilizes the texture of food products. Compared to additive E451(ii), E451(i) differs by higher solubility and wider use in meat processing.

In the food industry, E451(i) is used as a moisture-retaining agent, stabilizer, and emulsifier. It is added to sausages, seafood, frozen meat, and fish to preserve juiciness, prevent weight loss during heat treatment, and improve consistency. E451(i) is also used in processed cheese production.

More detailed information about the triphosphates group, their properties, and effects on the human body can be found in the article about food additive E451.