ELI5: Why does hot pizza so easily burn the roof of your mouth, even after resting, when we eat many other hot baked things that don't?

It's the cheese. It retains heat very well, compared to other foods. It also spreads easily along the mouth, giving a bigger surface area.

There are not many cheese foods we eat that are as hot as pizza. Pizza ovens are 600 to 700 degrees Fahrenheit. Fondue is 200 to 400.

[removed]

[removed]

Most baked items are airy, so a hot bite can equilibrate to your mouth temp quickly because the hot mass (temperature times mass times heat capacity of the material) is actually small.

Pizza contents have more heat capacity: protein, tomato sauce, cheese, oil. When these touch your mouth, the mass heat is quite larger and cause the burn.

Whenever someone says that that would love to die in a vat of molten chocolate should think again: it would be like burning the top of your mouth over your entire body!

It's because pizza contains more water than most baked dishes. And water is one of those substances that involve a relatively lot of energy to increase/decrease their temperature, and also to change phase (between liquid to gas, especially).

You might notice that a bowl of soup will cool longer compared to a block of fresh-from-the-oven brownie. Another good example is a plate of fried noodle cools faster than a bowl of soup noodle.

You'll also have to remember that heat will flow from the higher to the lower temperature. The temperature of something hot exposed to something cooler will eventually be in balance, that is, the hotter one will cool off, and the cooler one will be hotter.

So if hot pizza, or any other meal that contains lots of water, is exposed to your mouth which has much lower temperature, it will cool down, by releasing much energy (since water is hard to cool off, and needs to release much energy). And you feel the heat released by pizza in your mouth.

Try also to burn your mouth with lasagna, or freshly-baked apple pie.