It’s a bit of an oddity in a pizza crust, isn’t it? The main function it serves is to inhibit gluten formation. Gluten, as you may well remember is a type of protein that’s specific to grains derived from grasses (wheat, barley, rye…those sorts of things). Gluten proteins are long spindly molecules that bond to each other end-to-end and side-to-side to form a mesh that traps and holds gas bubbles. Since we want some gas bubbles but not terribly many in this Chicago-style dough (lest it become bready), we introduce what one might call “gluten inhibitors”, which is to say other starches of a neutral taste that not only have no gluten, but whose very presence interferes with gluten formation. Potato starch fills that bill. Potato also offers the side benefit of being very moist and very able to hold onto that moisture during baking. The upshot is a crust that is dense yet somewhat light, slightly moist and tender…just the way a Chicago-style crust oughtta be.