It's a favorite at movie theaters and home theaters alike, comes in varieties from plain to buttered to kettle, and only takes a few minutes to prepare. Although it's a snack food Americans have enjoyed for years, only few have asked, what makes popcorn pop?
The science of popcorn is fairly simple. Each tiny kernel contains a little bit of water surrounded by starch, all wrapped in the hard casing that we see. When the kernels are heated to 450° F, the water becomes steam and increases the internal pressure. Once enough pressure builds up, the hard outer shell can no longer stay together . After breaking, the starch puffs out rapidly as the inner pressure escapes. The internal heat also cooks the starch during the popping process, leaving us with a delicious snack.
As for those unpopped kernels that we find at the bottom of the bag, they most likely do not have enough water inside to build up the pressure needed for popping.
Now go enjoy some popcorn!