Tetrasodium Pyrophosphate (TSPP) — Frequently Asked Questions

Muscle proteins hold least water near their isoelectric point, around pH 5.0 to 5.5. TSPP is strongly alkaline, so it raises meat pH, and it also helps split actomyosin into actin and myosin. Together with salt, this lets more protein be extracted and more water be held in the meat structure, which improves cooking yield, bind and juiciness. It is usually part of a blend with other phosphates.

Some potatoes darken after cooking because iron forms a coloured complex with chlorogenic acid as the potato cools. TSPP, often together with sodium acid pyrophosphate, chelates the iron and prevents the grey discolouration in chips, fries, dehydrated potato and other potato products. The treatment is normally applied during blanching or as a dip, within the phosphate limit for the category.

Both are sodium diphosphates, E450, but they behave very differently. Tetrasodium pyrophosphate is fully neutralised and strongly alkaline, and is used for water binding, dispersion and chelation. Sodium acid pyrophosphate, E450(i), is acidic and is best known as a slow-acting leavening acid in baking powders and as a partner to TSPP in potato processing. They are not interchangeable.

TSPP dissolves slowly and only to about 6 to 7 g per 100 ml at room temperature, and salt makes dissolution harder. Add the phosphate to the water first, with good agitation, and allow it to dissolve completely before adding salt, cure and other ingredients. Chilled water slows dissolution further, so pre-dissolve in part of the water if necessary. Undissolved phosphate can crystallise on the meat surface.

TSPP is rarely used alone. Total added phosphate in cooked meat and poultry products is typically in the order of 0.3 % to 0.5 % of meat weight, with TSPP making up part of the blend. The legal limit is a group maximum for all phosphates expressed as P2O5, set per category in Annex II of Regulation (EC) No 1333/2008 and the UK retained equivalent, so check the current annex and include phosphate from all sources.

It is not highly toxic, but as a strongly alkaline powder it irritates the eyes, skin and airways. Wear eye protection and gloves, control dust when tipping and mixing, and wash off splashes promptly. Store it dry and sealed away from acids. The safety data sheet gives the classification, exposure controls and first-aid measures for the grade supplied.