What Makes Popcorn Pop?

January 15, 2016 | Elizabeth Knowles

popcorn kernels
Photo credit: Wikipedia User:Bunchofgraphes (CC BY-SA 3.0)

Watch the slow motion popping gymnastics!

If just the smell of popcorn makes my mouth water, make sure that you have a bowl nearby when you watch this YouTube video of popcorn popping in slow motion!

One of the exciting things about popcorn is that it covers a vast range of scientific fields: “This phenomenon contains interesting physics from different fields: thermodynamics, biomechanics and acoustics,” aeronautical engineer Emmanuel Virot and physicist Alexandre Ponomarenko told the Los Angeles Times. Virot and Ponomarenko are the authors of a French study on popcorn published in the Journal of the Royal Society Interface.

Davin Rose, a food scientist from the University of Nebraska-Lincoln explains how popcorn pops: As the kernels heat up, the water inside turns to steam once it reaches 212 degrees Fahrenheit (100 degrees Celsius). At that point, the water vapor builds up, and creates a molten mass inside that eventually breaks the pericarp — the hull surrounding the seed. When the pericarp gets too weak to hold the pressure in, it explodes and “legs” of starch materialize. The release of pressure on the legs causes the popcorn to jump into the air — it has nothing to do with the steam. Then, starch cools down and solidifies into the popcorn we know and love to eat. Although it is now twice the size of the original kernel, it is eight times less dense.

SEE ALSO: Scientists Solve Mystery of Chocolate Fountain Curtains

The French team investigated the best temperature at which to pop popcorn. 96 percent of the kernels popped at 356 degrees Fahrenheit (180 degrees Celsius), but only 34 percent popped at 338 degrees Fahrenheit (170 degrees Celsius).

The team furthered their research by examining the popping sound that popcorn makes and determining its origin. They hypothesised that it could come from one of three sources: the hull breaking open, the jumping off the ground, or the release of water vapor. The third option turned out to be the correct one.

“[T]he 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,” the researchers reported in their study.

In terms of corn, popcorn, known as Zea mays everta, is the only type that pops. However, it isn’t the only grain. Millet, quinoa, and amaranth do as well, but not with the same intensity.

Is it time for a snack yet?

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