Here’s Why Popcorn Pops
Plus: slow-motion footage of the miracle at work.
Adam Voorhes for Reader's Digest
The big bang may still befuddle us, but scientists just took a giant leap toward understanding the smaller (and arguably more important) bang that happens in your microwave. Thanks to a team of French researchers, we now have the most complete picture yet of popcorn’s seed-to-snack transition.
Inside every popcorn kernel’s shell, there’s a tiny droplet of water surrounded by a mesh of mostly starch. At 212 degrees Fahrenheit, the water turns into steam and mixes with the starch to create a hot, doughy mass. Pressure builds in the hull until finally, at 356 degrees, it bursts.
In the next 15th of a second, a lightning-fast circus act occurs: A “leg” of fluffy starch emerges from the fractured hull, kicking it up a few centimeters in a gymnast-like spin. Water vapor bursts from the hull as it does when you uncork a Champagne bottle, emitting that signature popcorn pop. The hull continues to bloom as it flips and cools, finally converting that hot vapor and starch into the popcorn fluff we know and love.
At the end of the show, each inside-out kernel is about twice as large and one eighth as dense as it was pre-pop. Whether you should cover yours in butter or olive oil is a question for another day.
See it all happen in slow-motion, courtesy of researchers Emmanuel Virot and Alexandre Ponomarenko (video via Haaretz.com):