E450ii - Trisodium diphosphate

Trisodium diphosphate is one of seven diphosphate salts specified under E 450 in Great Britain. “Diphosphate” means two phosphate units joined by a shared oxygen — a pyrophosphate — and the sodium count in front of it sets how acidic or alkaline the salt behaves in a mix.

Diphosphates earn their place in two jobs. In baking they are the acid half of a chemical raising system, reacting with bicarbonate to release carbon dioxide, with the particular salt chosen to control when that gas arrives — at mixing, or in the oven. In meat and fish processing they raise pH slightly and unwind muscle proteins so they hold on to water, which is why brined chicken and frozen prawns lose less weight when cooked.

Baking powders and scone or cake mixes, processed and reformed meats, brined poultry, frozen prawns and other seafood, canned soups, potato products and some cheese products.

Diphosphates are authorised in Great Britain as E 450. The assimilated specifications list seven named forms — (i), (ii), (iii), (v), (vi), (vii) and (ix) — of which trisodium diphosphate is E 450(ii).

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.

Added phosphates in meat and fish are also a water-retention aid, so part of what is being paid for by weight is water. Labels must declare the additive, but not how much of the pack weight it holds.

• FSA Register of Food Additive Authorisations — E 450
• 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 450(ii))