People have been eating popcorn for thousands of years. It was originally discovered by Native Americans in prehistoric times. Popcorn is a type of corn, and has the scientific name Zea mays everta. While it grows in the same way as other types of corn, only popcorn can be popped. This tasty snack is surprisingly nutritious.

Parts of a popcorn kernel
The composition of a popcorn kernel is what enables it to pop. At the center of each kernel is a small amount of water. Surrounding the water is soft starch. Surrounding the starch is an outer hull that does not let water pass through.

How popcorn pops
When a kernel is heated, the water inside expands and turns to steam. The steam cannot simply seep out of the kernel because the kernel's outer hull is waterproof. Instead, pressure builds up inside the kernel. By the time the temperature of the kernel reaches 347 degrees Fahrenheit, the pressure inside will be an astonishing 135 pounds per square inch, and the kernel will explode. The hot starch will inflate and spill out of the kernel, becoming as much as 50 times larger than its original size.

History
The oldest known popcorn was found by archeologists in a cave in New Mexico and is about 5,600 years old. European explorers learned about popcorn from Native Americans in North and South America. Popcorn became popular in the United States in the mid-1800s. In the 20th century, its popularity increased when it was sold in movie theaters.

Benefits
Popcorn may have a bad reputation because it is often cooked in unhealthy oils and topped with gobs of butter. But popcorn itself, without the added fat, is a healthy whole grain, and whole grains are good for the heart. Popcorn eaters may get more than twice as much whole grain in their diet as non-popcorn eaters. The healthiest way to prepare popcorn is to air pop it or to use a healthy fat such as olive oil.

Storage
If popcorn kernels lose their moisture, they won't pop properly. Don't store unpopped kernels in the refrigerator, because that could dry them out. Instead, keep them in a cool place in airtight containers.