Given that Thanksgiving is right around the corner and grilling out has given way to cooking (or ordering) in, I thought it might be fun to consider the weather indoors rather than outdoors this week. Before I begin, I wish to give credit to Harold Morowitz for writing the book "The Thermodynamics of Pizza," a collection of 52 essays on science in every day life. It's a fabulous book and served as the inspiration for today's blog.
Okay pizza lovers! Quick quiz! If you take a bite out of a slice of piping hot pizza, what part of your mouth is most likely to get burned?
Is it A) the tongue or B) the roof of your mouth?
It's okay if you wish to take 30 minutes to formulate your answer, I'll wait.
Now that you have your pizza, give it a try!
Although most of you were thinking "tongue" before you took that bite, that area along the roof of your mouth just behind your teeth is suddenly feeling a little numb.
Look at your pizza very closely. It is basically three layers, a doughy bottom (crust), a thick paste (tomato sauce) and a solid (cheese) that has undergone a complex transition involving protein de-naturation and lipid rearrangement. (That means it melted!) For now we will neglect toppings.
Heat is always transferred from high temperature objects to low temperature objects. This is why your kitchen doesn't freeze over when you put a glass of ice on the counter. Instead, the heat from the warmer room is transferred to the colder ice, melting it, and warming it until the resulting liquid is at the same temperature as the room.
Your hot pizza transfers heat too! But, why does more heat exit the top of the pizza than the bottom?
The key is the crust! The dough bakes into bread, a substance with a large number of non-connecting air spaces. Air is a poor conductor of heat. This is why you are told to dress in layers when it is cold outside. By dressing in layers, you trap air between the layers. Because air is a poor conductor of heat, you stay warmer. Pizza crust is an excellent insulator because of the unconnected air spaces throughout. That means the crust doesn't transfer heat very well.
Do you want to convince yourself that the air spaces in bread are poor conductors of heat? Try to burn a piece of toast! Again, I will wait.
Yes, I know, you burned it on the outside! But break open that toast and look at the inside! Is it burned inside? Of course not! This is why when you burn toast you simply scrape off the burned particles on the outside and salvage that piece of toast.
(Advice from your Fox Weather kitchens = a hand-held cheese grater works perfectly for this toast-scraping task! You can also salvage burnt grilled cheese sandwiches with this same technique!)
The inside of the toast survives because of the air spaces in the bread and their inability to transfer heat effectively. That takes us back to the pizza.
Your pizza vendor likely cooked the pizza in an oven that was over 900F. (This is why frozen pizza in your home oven never works as well as pizza from your favorite pizza place. Your local fire department does not allow you to have the capability to heat something to 900F in your kitchen!) That 900F pizza transfers a lot of heat. Because of the insulating crust on the bottom, most of the heat gets transferred through the top.
The result? When you take a bite, most of the heat goes up, burning the roof of your mouth in the process.
One more note. Have you ever noticed anything interesting about the construction of that box your pizza was delivered in? Check it out and let's talk about your observations on this topic in the comment section below!
Blogger's Anecdotes:
Morowitz also wrote "Mayonnaise and the Origin of Life." I am still searching for the mustard version.
Thanks to a memory prompt from an avid reader, I have finally finished this blog. (Thanks for the note TexasWeatherGirl!)
