The Gooey Science of Melting Cheese

Find out why in this edible experiment that’s perfect to do with kids on a rainy afternoon (or for a school science fair!). 

Don’t use fresh mozzarella, mild cheddar cheese, or finely grated Parmesan cheese. You can swap the flour tortilla for corn tortillas or even small slices of bread.

1. Adjust oven rack to middle position and heat oven to 200 degrees.

2. Use chef’s knife to cut tortilla into 3 equal wedges.

3. Arrange tortilla wedges on rimmed baking sheet. Use masking tape and marker to label baking sheet “Mozzarella” by left tortilla wedge, “Cheddar” by center tortilla wedge, and “Parmesan” by right tortilla wedge. 

4. Sprinkle mozzarella in even layer on left tortilla wedge. Sprinkle cheddar in even layer on center tortilla wedge. Sprinkle Parmesan in even layer on right tortilla wedge.

5. Make a prediction: Do you think these 3 cheeses will melt the same way? Why do you think so?  

6. Place baking sheet in oven and bake for 10 minutes.

7. Use oven mitts to remove baking sheet from oven and place on cooling rack (ask an adult for help).

8. Observe your results: Do the 3 melted cheeses look the same? In what ways do they look different? Which would you choose for your grilled cheese sandwich or pizza? 

9. Eat your experiment: Snack on any (or all) of your cheesy creations. What do you notice about their flavor? Their texture?

When we conducted this experiment in the ATK Kids Recipe Lab, our mozzarella melted into gooey perfection, our cheddar was melty but greasy, and our Parmesan didn’t really melt at all. 

The way a cheese melts has a lot to do with the cheese’s age and how much water it contains. But before we get to that, let’s talk about melting in general: Cheese doesn’t melt the same way ice does—it doesn’t go straight from a solid to a liquid. That’s because ice is made of just one “ingredient” (water) while cheese is made up of a whole bunch of things, including protein, fat, and water.

Cheese is made of a network of proteins, like lots of tiny cages, surrounding bits of fat and water. When cheese heats up, the fat turns from solid to liquid. Then its proteins loosen up, which makes the cheese “flow” like a thick liquid. 

As cheese ages, it loses water through evaporation (this also concentrates the cheese’s flavor!). Cheeses with less water don’t melt well because their proteins cling together tightly and they need more heat to melt. Plus, aged cheeses are less flexible when they melt. Instead of flowing smoothly, they squeeze out tiny droplets of fat. 

Parmesan is the oldest of our cheeses. It can be aged for more than one year and it barely melts at all, but it packs a TON of flavor. 

Sharp cheddar is our middle-aged cheese—it’s aged for six to 12 months. While sharp cheddar does melt, it leaks greasy melted fat (this is called “breaking”). 

Mozzarella is our youngest cheese—it isn’t aged at all, which means that it still contains lots of water and is excellent at melting. 

Young cheeses, such as mozzarella, mild cheddar, and Monterey Jack, are your best bet for adding gooey melted cheese to dishes, while aged cheeses add tons of flavor but keeps things crispy. See this cheesy science at work in the recipes below.