The Science of Popcorn

popcorn popping how and why does it pop


The folklore of some Native American tribes told of spirits who lived inside each kernel of popcorn. The spirits were quiet and content to live on their own, but grew angry if their houses were heated. The hotter their homes became, the angrier they would become, shaking the kernels until the heat was too much. Finally, they would burst out of their homes and into the air as a disgruntled puff of steam. (How Does Popcorn Pop?, n.d., US Department of Agriculture)

Beyond Folklore, popcorn is not only a tasty snack but also fascinating to watch and hear pop. But, why would a corn kernel pop and suddenly change appearance. Why would would it go from being one thing to something else in a blink of an eye? And what is with that sound? Let's dig a bit deeper into all these questions to find the answers about your popped corn.

Popcorn is actually a special variety of corn, and it is the only one that pops. The key to popcorn is the unique design of its kernels. Corn is made up of various layers. Most importantly, its kernel consists of a very hard, mostly nonporous outer shell. Inside the kernel there is not only the seed for a new corn plant but also water and soft starch. While you’re heating popcorn, you’re not only heating the outer shell you are heating the water and starch inside.

As the popcorn heats and gets hotter and hotter the water trapped inside starts to turn into steam. If the kernel is heated to a high enough temperature, this steam will start to evaporate. When moisture evaporates it expands. Due to the hard outer shell the expanded evaporated moisture has nowhere to go.  It's trapped and this results in a buildup of pressure inside the kernel. At some point, the hull won’t be able to resist the pressure anymore. At that moment the popcorn pops! This POP turns the hull inside out. What's more,originally the characteristic popping sound was thought to come from the cracking of the hull. However, it actually results from the vapor release after the kernel has cracked.

So there you have it in a "corn" shell. While, it's certainly fascinating to understand, it's much more enjoyable to eat! 

What's your favorite way to eat popcorn? Plain, Buttered, Salted? Covered in Caramel or Cheese? However you enjoy it one things for sure, it's a crowd pleasing snack that is irresistible to almost anyone!




How Does Popcorn Pop?, n.d., US Department of Agriculture

Why Does Popcorn Pop, 10/14/2020,