Popcorn, like all grains, contains water. About thirteen and a half to fourteen percent of each kernel is made up of water. So when a popcorn kernel is heated above the boiling point of 212 degrees Fahrenheit, this water turns to steam. This steam creates pressure within the kernel, causing the kernel to explode and turn itself inside out.
But, if the water inside a piece of popcorn is what makes it pop, why don't other grains pop as well? Wheat and rice contain water, so why don't we sit down to watch a movie with a bucket of popped rice or popped wheat?
The answer lies in the differences between the outer coverings, called hulls, of popcorn and other grains. Unlike rice and wheat, and unlike even regular corn, popcorn has a non-porous hull that traps steam. With the porous hulls of other grains, steam easily passes through, so no significant pressure is produced. These grain...
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