Being a scientist is not just about solving big problems like curing diseases or fixing global warming. Scientists are very curious, even when it comes to ordinary things that others take for granted.
A pair of scientists in France was curious about why popcorn jumps and pops. They caught the stages of the pop with a high speed camera and sound recordings, and then they watched it in slow motion. The scientists learned that popcorn jumps and somersaults like a gymnast, and that the mysterious pop sound is like a champagne bottle getting uncorked.
Compared with sweet corn like you eat for dinner, popcorn kernels have a thicker outer shell and a softer, starchy center. The tough shell stays together while the soft inside heats up. When the temperature is above 100 C (212 F), the water inside the kernel boils. This creates pressure inside the kernel causing the shell to break and the fluffy white center to expand out. The scientists found that the best temperature for making popcorn was 180 C (356 F), the point where the shell can no longer withstand the pressure.
There is no rocket effect from the steam escaping as one might think. Instead, what happens is a ‘leg’ of starch emerges from the kernel and pushes off the surface, causing the popcorn to jump and do somersaults in the air. The scientists learned that the physics of the jumping popcorn is very much like a gymnast using their legs to jump and somersault.
The pop sound comes before the jump, right when the steam gets released. The researchers explain that the sound comes from the inside of the popcorn due to the sudden drop in pressure, like when the cork comes off a bottle of champagne.
Can these scientists tell us how to make a better batch of popcorn? According to the scientists, if kernels stay at the bottom of a hot pan too long their shells get damaged—so make sure to keep shaking the pan. Thanks, Science!
For a great video on the science of popcorn, Click Here!