Popcorn is one of the world's favorite snacks, but have you ever wondered why only certain corn kernels explode when heated? Food scientists have revealed the fascinating science behind this everyday phenomenon.
According to experts, popcorn is made from a special variety of corn known as Zea mays everta. Its kernels have a tough, moisture-resistant outer shell and contain starch along with about 13–15% moisture inside.
As the kernel heats up, the trapped water turns into steam. Because the hard outer shell prevents the steam from escaping, pressure builds rapidly inside the kernel.
Eventually, the pressure becomes too great, causing the shell to burst. The hot starch expands instantly, cools within seconds, and forms the fluffy popcorn we eat. A single kernel can expand to 30–40 times its original size.
Scientists also explained that some kernels fail to pop because they contain too little moisture or have tiny cracks in the shell, allowing steam to escape before enough pressure can build.
