Disodium Hydrogen Phosphate (DSP)

About This Product

Disodium hydrogen phosphate, usually called disodium phosphate or DSP, is authorised as food additive E339(ii) in the EU and UK. It is traded in several forms: anhydrous (CAS 7558-79-4, Na2HPO4, 141.96 g/mol), dihydrate (CAS 10028-24-7) and dodecahydrate (CAS 10039-32-4). The anhydrous and dihydrate forms are white powders or granules, while the dodecahydrate is a coarse crystal that loses water in warm, dry air. Its solutions are mildly alkaline, around pH 9 at 1 %.

DSP is a buffer, a stabiliser and an emulsifying salt. In evaporated and condensed milk, UHT dairy drinks and coffee creamers it buffers the milk and binds calcium, which prevents gelation and coagulation during heat treatment and storage. In processed cheese and cheese sauces it is one of the emulsifying salts that make the casein disperse and emulsify the fat. It is also used in quick-cooking cereals and instant puddings, in meat brines, and as a sodium and phosphorus source in nutrition products. Use levels are low, typically a few tenths of a percent in dairy drinks, while emulsifying salt blends in processed cheese typically total about 2 % to 3 %.

The form matters for dosing and handling. On a phosphate basis 1 kg of anhydrous DSP corresponds to about 1.25 kg of dihydrate and about 2.52 kg of dodecahydrate, so confirm which form a recipe was written for. The anhydrous form suits dry blends and gives the most phosphate per tonne transported; hydrated forms dissolve easily but are more sensitive to caking and water loss in storage. Dipotassium phosphate (E340(ii)) does the same job without sodium and is more soluble, which is why it is often preferred in creamers and protein drinks.

Specifications normally cover the assay on the dried basis, P2O5 content on the anhydrous basis, pH of a 1 % solution, loss on drying for the declared form, water-insoluble matter, fluoride and heavy metals. The grade should meet the E339(ii) purity criteria in Regulation (EU) No 231/2012 and its GB equivalent, or FCC or JECFA for other markets.

Phosphates are authorised by food category under Annex II of Regulation (EC) No 1333/2008 and the UK retained equivalent, mostly with a group limit for E338 to E452 expressed as P2O5, so account for every phosphate in the recipe and check the current annex for your category. Foods for infants and young children follow separate, stricter provisions. Declare it by function, for example stabiliser: sodium phosphates, or emulsifying salt: E339.

Store sealed in a dry place at stable temperature; hydrated forms can effloresce and then cake. Dust irritates eyes, so use eye protection. When you enquire, state the form (anhydrous, dihydrate or dodecahydrate), particle size, application, purity standard, pack size, annual volume and destination, and the approval documents you need.