Have you ever stopped to think about what happens so that the grain of maize turns a popcorn? Once again physics has the answer and it is related to the vapor pressure.

In fact, the popcorn popping process had been without exact explanations for quite some time. It was through videos with high-speed cameras that it was possible to understand what happens in this transformation of maize. For easy explanation, first check out this video of a popcorn bursting into super slow motion:

Instead of the popular belief, the popcorn popping noise is not caused by breaking the grain or its impact on the surface. In fact, 14% of the core is composed of water, which evaporates when it reaches 100°C. However, the shell only breaks at 180°C, which means that until then the steam is contained inside the shell, which ends up functioning as a pressure cooker. It’s precisely when the shell breaks off, releasing the pressurized steam, that the famous “pop” can be heard. In addition, the ruptured grain itself functions as a speaker, amplifying the sound.

Another very interesting point to observe is that when this overflow occurs: the steam escapes through the crack taking also the interior made of starch and fibers. This is how the grain of maize turns into popcorn as we know it.

Isn’t so cool to see how physics is present even in popping popcorn? Check out our blog and discover several ways in which physics is present in our lives.