What it does
Natural cheese will not simply melt into a smooth mass, because its calcium is locked into the casein structure. Emulsifying salts exchange that calcium for sodium, which releases the casein and lets it hydrate, disperse and act as an emulsifier for the fat already present. The product is not emulsified by the salt; it is emulsified by the casein the salt set free. Different salts also buffer to different pH values, and the pH reached decides the firmness and the melt.
Where it works
Processed cheese, cheese spreads, and analogue cheese systems where casein is present.
Where it does not
There is nothing for them to do in a system without casein, so a fully plant based analogue gets no benefit. They also carry a phosphate or citrate declaration, which some positioning will not accept.
What it interacts with
Calcium, which is the whole mechanism. pH, decisively. The cheese itself: a young cheese and a mature one need different salt systems for the same result.
