Cooking popcorn might be as delightful as eating it. The whole operation lasts just few minutes and implies three entertaining moments when the pan gets heated: the kernels burst open, jump, and emit an iconic ‘’pop’’ sound.
While early studies have focused on conditions required for successful popping of popcorn, aeronautical engineer Emmanuel Virot and physicist Alexandre Ponomarenko have gone into the physics of popcorn popping in greater detail than ever before.
In their study, recently published in the Journal of the Royal Society Interface, the two French scientists report new insights into the source of the popping sound, the forces that make kernels jump and the ideal temperature to pop the most corn.
It is well known that when the kernel is heated above 100 degrees Celsius, its water content (moisture) turns into water vapor and expands against the hull, which then fractures into a billowy, white flake. Using thermodynamic analysis Virot and Ponomarenko found that 180 degrees Celsius (356 °F) is the perfect temperature to pop the most corn. Using a high-speed camera, the pair observed that when the critical temperature is reached, the first thing that protrudes from the grain is a structure like a leg. As the ‘’leg’’ heats up, it jumps into the air where it spins an average of 490 degrees before settling back down. The two researchers observed the popcorn kernel performs a maneuver like a running gymnast turning a somersault which dismantles previous theories of a rocket effect.
As regarding the source of the popping sound Virot and Ponomarenko found that this does not come from the hull fracturing or the flake hitting the plate, as many of us may think. Instead, the sound comes from the release of water vapor as the kernel opens, which turns the flake into an “acoustic resonator”- much like the pop from a champagne bottle when the cork is removed.