Big grains, thin shell
Potato starch grains are large. Many are over 30 microns wide. Cornstarch grains are about half that size. Big grains swell and dry into a thin, brittle shell.
No gluten, no chew
Wheat flour has gluten. Gluten makes a bready, chewy crust. Pure starch has none. So it shatters instead of bending.
It changes again in liquid
Potato starch thickens at a low heat, near 60C. In hot broth it turns clear and slippery. That is why agedashi tofu feels silky.
Ryota says:
I fried the same tofu in three powders. Potato starch won on crunch and on the silky edge.
