How does popcorn “popped”?

Whether popcorn can be successfully “popped” out depends on the firmness of its skin, and whether it can effectively transfer external heat to the starch inside the grain. When the temperature rises, the moisture inside the kernels turns into steam and is gradually pushed toward the husk. When the pressure exceeds 200 degrees Celsius (400 degrees Fahrenheit), the husk bursts, and the starch and steam inside it expand and explode as the pressure inside and outside equalizes.

Scientists have also found a way to double the size of the corn kernels that eventually pop. If a vacuum pump is used to reduce the pressure of the air inside the pump while heating the kernels, when it bursts, it can burst more than it normally does.

Today, popcorn also enjoys a healthy reputation. While you may think of popcorn as a sweet, salty, butter-filled snack reserved for special occasions like movies or carnivals, it’s actually a whole grain food, low in fat and salt before it’s seasoned.