Thought you were talking about the original use of Pie crust. Back in the middle ages (1300 to 1500's) The crust was just to preserve the contents of the pie. Before eating the contents- you discarded the crust. It used to be rock hard and inedible- but would keep the contents clean and edible for weeks. Think McD's still have the recipe for the crust but they use it round some inedible contents.