Hi. I am on the hunt for improved pie crusts (i.e., nothing can possibly go wrong). I found something interesting in my voluminous box of recipes which mentions to "rub the pie crust with egg white [before prebaking for a pumpkin pie]". What would be the purpose of this? We are to prebake the crust at 450 degrees for 5 minutes, then put the custard mixture in and bake the whole thing. Thanks for your help!