What Makes Popcorn Go 'Pop'?

We know we love popcorn, but may not have known why it makes its distinctive popping sound … until now.
Here are a few of the things most of us know about popcorn:

1. We love the way it tastes and smells.

2. We especially love it while we’re watching a movie.

3. Sometimes, when we’re feeling decadent, we like it with butter.

4. Other times, when we’re feeling more virtuous, we enjoy it more or less straight up.

5. There’s nothing quite so distinctive as the sound it makes when it pops.

Here’s one thing you probably didn’t know: why it makes that distinctive popping sound when it pops.

A team of French scientists recently provided an answer. According to their study, published in the Journal of the Royal Society Interface and noted on Consumerist, it takes just hundredths of a second for a piece of popcorn — once it has reached a critical temperature of 180 degrees C (356 degrees F) — to go through its transformation from unpopped kernel to fully popped “flake.” In that time, it “bursts open,” jumps due to the compression of a “leg” of starch — sort of like an explosive plant or an animal using its muscles to leap, the researchers explain — and emits a popping sound.

To pinpoint the source of that sound, the researchers synchronized video recordings with audio recordings of popcorn popping and determined that the sound is made not by the rupturing of the hull of the kernel, which they found to be more or less soundless, nor by the popcorn rebounding off a surface, because the sound occurs before popcorn makes its dramatic jump. Instead, they concluded, the sound is made by the release of water vapor within the popcorn at the key moment of expansion.

“More precisely,” the researchers write, “the pressure drop excites cavities inside the popcorn as if it were an acoustic resonator. Such a scenario has been applied to volcano acoustics and to the ‘pop’ of champagne bottle cork.”

So it’s like a mini celebration in every piece of popcorn? How very festive!

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