What You Need to Know
The pastry dough layers trap steam during baking, creating a puffed, flaky structure. The Maillard reaction between sugars and proteins in the crust and egg glaze produces melanoidins that give the golden color and savory aroma. Egg proteins denature upon heating, forming a glossy, firm surface that seals moisture inside.
The Science
Primary Reaction
Maillard reaction and steam generation