Popcorn is a variety of corn kernel, which forcefully expands and puffs up when heated.
A popcorn kernel’s strong hull contains the seed’s hard, starchy endosperm with 14-20% moisture, which turns to steam as the kernel is heated. The pressure continues building until it exceeds the hull’s ability to contain it. The kernel ruptures and forcefully expands, allowing the contents to expand, cool, and finally set in a popcorn puff 2 to 5 times the size of the original kernel.[1]