Polyphosphates are naturally occurring in all forms of life and may also include other elements, such as sodium, potassium and calcium to form compounds such as sodium polyphosphate (E452(i)), potassium polyphosphate (E542(ii)) and calcium polyphosphate (E542(iv) also 544).

Polyphosphates are legally permitted additives that are widely used to aid processing or to improve the eating quality of many foods, particularly meat and fish products.

Phosphates that are naturally present in muscle tissue play an important role in rigor mortis of meat and fish. Adding polyphosphates to seafood, such as prawns, once caught proves very useful in increasing the quality and shelf life of the product as it improves their water-binding capacity

One outcome of this treatment is a significant gain of weight caused by the retention/uptake of water and natural juice into the fish tissues. The use of phosphates has to be declared but the practice is legal. (Once polyphosphate breaks down, it ultimately does so to naturally occuring monophosphate and so it cannot be easily distinguished from normal phosphate).

To aid in the declaration of polyphosphates we have developed a test that detects the amount of 'added' phosphates in prawns, distinguishing between the naturally occurring levels of phosphates and the level of added phosphates. In prawns, monophosphate is naturally occurring, where as di-phosphate and tri-phosphate are not, therefore the detection of diphosphate and tri-phosphate in prawns would confirm the use of polyphosphates. This newly developed NMR (nuclear magnetic resonance) based in-house validated test can successfully differentiate between the different forms of phosphates in prawns.