Reactions of Proteins and Polyphosphates

One of the early qualitative tests to determine whether or not a substance was an orthophosphate or a condensed phosphate was to mix the phosphate in question with a protein such as egg albumin. If the phosphate reacted with the protein and precipitated, it was likely the phosphate was a condensed phosphate. The text was not foolproof, but was a good indicator. Many polyelectrolytes precipitate proteins. If one knows that the substance under test is a phosphate of some description, then this narrows the room for error. 

The interaction of gelatin and polyphosphates is tenacious and the coascervates are refractory enough to form solids that can remain in moist conditions for extended periods. This action is readily observed in the precipitation of gelatin in leather with short-chain polyphosphates. 

Howard J. Buttery of the Encapsulated Products Division of the 3M Company is a leading scientist in the chemistry of encapsulation. I am indebted to him for the following account of the reactions of gelatin and polyphosphates. 

Phase separation can be induced by several processes. Simple coacervation results from introducing an overall water deficiency by the addition of a more hydrophilic agent to a concentrated solution of the macromolecule. Complex 

Gelatin coacervates have received the most attention both academically and commercially. However, many other aqueous and nonaqueous systems have been studied for various applications, such as encapsulation. Coacervation equilibrium has been applied to fractionation of polymers.  

---