Reader Charlie writes in with these additional questions:
1) I don’t understand the starch mesh. Are the starch granules burst like in a gravy? If they aren’t heated to that point- aren’t they just swollen starches (individual)?
2) True heat would denature the proteins but wouldn’t over-heating then tighten these same proteins then tighten as with steak or bread?
Regarding #1, though I’ve heard cooks on some cooking shows talk about the way starch granules “explode” when they’re heated in water, that’s really an exaggeration. The reality is more like what I described, with individual molecules steadily breaking loose from their granules like reeds off a bundle. The granules themselves stay more or less intact. That’s good because it’s the semi-intact granules that are mainly responsible for the thickening. They are the “fish” that get caught in the starch molecule “net”, as it were. The more of them that become immobilized, the less the mixture flows and the thicker it gets. What’s especially interesting is that you can overdo this process, which is to say you can heat the mixture until the granules really do break down utterly. At that point there’s nothing left for the starch net to hold and the mixture thins back out again. If you’ve ever simmered a starch-thickened sauce or gravy for too long, you may have had this experience.
Regarding #2, you’re quite right that too much heat could conceivably denature the proteins in the batter to the point that they bunch up and won’t function at all. That would take a heck of a lot of cooking, however. Keep it to three minutes and you should be in good shape.
Thanks for the great questions, Charlie!