Why Does Popcorn Pop

Popcorn is a special type of corn with a very hard outer shell. Each kernel has a tiny drop of water inside it. When the kernel is heated, the water turns to steam. The steam builds up pressure until the kernel explodes and turns inside out. That is how popcorn pops!

The Science of Popping

Each popcorn kernel contains a small amount of water inside its starchy center. When the kernel is heated to about 356 degrees Fahrenheit, the water turns into steam. The steam puts pressure on the hard shell. When the pressure gets too high, the shell bursts open. The starchy inside puffs up into the fluffy white shape we eat.

Why Not All Kernels Pop

Sometimes kernels do not pop. These are called old maids. A kernel will not pop if its shell has a crack that lets steam escape. It also will not pop if it has dried out and lost its water. Fresh popcorn with uncracked shells pops the best. About 98 percent of kernels should pop if the corn is stored properly.

Fun Facts

• Americans eat about 15 billion quarts of popcorn every year.
• Popcorn can pop up to three feet in the air.
• People have been eating popcorn for over 5,000 years. Ancient popcorn was found in caves in New Mexico.

Did You Know?

Popcorn is the only type of corn that pops. Regular sweet corn and field corn do not have the right kind of hard shell to trap steam inside!