The skin is forming because of proteins, just like if you cook milk or anything else that's got a coagulant protein in it.
Alton BrownI canโt talk about anything or write about anything if I donโt understand it. So a lot of the stuff that I go through and a lot of the time that I spend is understanding.
Alton BrownWhat tends to happen is that people will go - they've got hot broth, you know, they've added some liquid to their drippings, they've brought that up to heat. And then they try to add in a big clump of just kind of a handful of flour, and of course, it turns into library paste.
Alton Brown