The Thermodynamics of Baking

I love baking. However, I love eating the food even more than the work that goes into its preparation, so combined with my laziness and need to stop eating junk food after the extremely tasty month of December, I don't bake very often. However, last night my dad did that for me; he made a batch of very yummy biscuits (one of which is pictured here) that even though I had just eaten a large dinner and half a cinnabon I immediately dove into. (I need to learn some self control :-) ) But this morning while considering whether to eat another one, as well as pondering thermodynamics in daily life, I thought, "Hey! Biscuts are full of thermodynamics, at least the baking process anyway." When the oven is turned on, the coils producing the heat begin to heat up the air inside the oven by conduction, which then circulates by convection due to the differing densities between the warm and cool air, eventually bringing the entire oven up to temperature. The heat is prevented from escaping by the walls of the oven which, I would guess, are covered with a high specific heat material and/or a material that is designed to reflect the infrared waves from the hot air and heating coils. Then when the biscuits are put in, they begin to heat up by conduction as well. However, the outside will heat up faster, as it has more contact with a larger heat source than the inside does. Then when the outside begins to cook and get hard, it doesn't allow for the expansion of the biscuit anymore as the temperature goes up, turning an isobaric process into an isochoric process. However, that means that as the temperature of the inside rises, the pressure builds. But the outer layer isn't strong enough to contain the pressure, so it splits and releases the pressure, allowing the inner contents to expand once more, just like this biscuit started to do, but the picture's not good enough to see it very well. But sorry, there can be no more pictures of that biscuit to show the split; notice that the biscuit is sitting on a cutting board. It was eaten with strawberry preserves soon after that picture was taken. Yum!