is curdling a chain reaction?

Question

or, like in general reactant-product reactions, will the reactants get used up if there arent enough, and the curdling stop? like, if the milk is just introduced to a tiny but adequate amount of acid to start the curdling, will all of the colloids come out of suspension?

Answer 1

Yes, it is like what you refer to as "reactant-product" reactions. It isn't a "chain reaction", but will terminate once the "reaction" is complete. Curdling is essentially a physics-chemical process, and because the chemical nature changes, it is considered irreversible.