E452iv - Calcium polyphosphate

Calcium polyphosphate is a glassy, long-chain phosphate — many phosphate units strung together rather than the two of a diphosphate — carrying calcium as its counter-ion. It is made by melting calcium phosphate at high temperature and cooling it fast enough that it sets as a glass rather than a crystal.

Long chains make it a strong sequestrant: it grips calcium, magnesium and iron ions tightly, which stops them clouding a drink, discolouring a canned food or catalysing fat rancidity. It also disperses proteins, which is what makes polyphosphates useful in processed cheese and in reformed meat.

Processed cheese, canned and cured meats, some fish and seafood products, powdered drink and dessert mixes, and dietary supplement tablets where it doubles as a calcium source.

Polyphosphates are authorised in Great Britain as E 452, with calcium polyphosphate specified as E 452(iv).

EFSA re-evaluated the whole phosphate group in 2019 and set, for the first time, a group acceptable daily intake of 40 mg per kg of body weight per day, expressed as phosphorus, covering E 338–341, E 343 and E 450–452 together. The Panel added two caveats worth knowing: the ADI does not apply to people with moderate to severe reduced kidney function, and estimated intakes already exceed it for infants, toddlers and children.

• FSA Register of Food Additive Authorisations — E 452
• EFSA (2019), Re-evaluation of phosphoric acid–phosphates – di-, tri- and polyphosphates (E 338–341, E 343, E 450–452)
• Assimilated Regulation (EU) No 231/2012 (specifications, E 452(iv))