The science behind why pepperoni curls on pizza

There are several hypotheses, which, according to Serious Eats, can be summarized in three ideas: the thickness of the pizza, the contraction of the pepperoni crust during cooking, and the fluid dynamics of the filling. Although it may seem complicated, the answers are surprisingly simple, according to Meat+Poultry, and a good curl gives the pepperoni its much-loved flavor and texture.

The first explanation is thickness. The top of the pizza is exposed to the oven's air, so it heats up faster than the base, which is covered in cheese and pepperoni. As a result, the top cooks faster and shrinks more, as does the pepperoni. The effect is greater with a thick slice, according to Home Kitchen Talk, because there's more food between the top and bottom.

The second hypothesis concerns the wrapping. There are three types: natural, collagen, and unwrapped, according to Slice Pizzeria. According to Meat+Poultry, if the wrapping is removed before baking, the pepperoni will be flat. If the wrapping remains during cooking, it will shrink and its edges will curl.

The third explanation points to the meat's moisture content. The collagen sheath doesn't stretch as much as the fibrous one, and the meat, pushed toward the center and stuck to the sides of the slice, affects the curl pattern. This downward flow of meat and fat would cause the pieces to curl more with collagen than with fibrous, according to Meat+Poultry.

Fans have put these ideas to the test. According to Home Kitchen Talk, the temperature difference between the top and bottom of the pepperoni affects how much it curls, and the thickness also determines whether it curls up or down. Pepperoni stuffed in natural or collagen casings curls more than uncased pepperoni.

Removing the wrapper before putting the pizza in the oven doesn't alter the crust, according to Meat+Poultry. In short, the first and third hypotheses seem to be true, while the second has little basis.