Are starch-thickened mixtures gels?

Good question, reader Nils, the answer to that is yes, though it’s a different sort of gelling process relative to a protein gel. In a protein gel the molecules that make up the network are bonded to each other chemically. The individual molecules bond end-to-end and side-to-side with one another inside a watery medium. The result is restricted flow and thickening. Starch gelling is a bit different. As starch molecules separate from the flour granules from which they came they get tangled up with each other. That tangle also restricts the flow of the water molecules around them and creates thickening. The key difference is that the starch molecules aren’t bonded to one another, or if they are only very weakly, and will wash away if the heating process goes on too long. In that case the flour granules in the mixture dissolve completely and the whole network collapses. Great question!