What each one does
Phosphate raises pH, dissociates actomyosin, stabilises the emulsion, improves yield and chelates the metals that drive oxidation. A replacement system addresses those separately: an alkaline material for pH, something to carry water mechanically, an emulsifying protein, and an antioxidant.
What decides it
Whether the brief is clean label or cost. If it is clean label, the question is only how well the five functions can be rebuilt. If it is cost, phosphate is almost always cheaper and the project should be questioned.
Where the obvious answer is wrong
The obvious answer is to find the one material that replaces phosphate. There is not one. The projects that stall are the ones run as a substitution, and they stall at the fourth function rather than the first.
