A team of French scientists have been busy examining one of the world’s most popular snacks: popcorn. For this, they have determined the critical temperature at which popcorn bursts. The outcome of their examinations is that when popcorn reaches a threshold of 180 degrees Celsius (or 356 degree Fahrenheit) the outer shell of the corn will burst open to reveal its crunchy glory, regardless of the size and shape of the grain.
The scientists additionally revealed the way that popcorn jumps as it breaks open, together with the sound emitted as water vapor is suddenly released (the marvelous “pop” sound.) This all happens very, very quickly, with the temperature threshold to pop sound occurring in a hundredth of a second.
Popcorn is a type of corn (maize, Zea mays var. everta) that expands from the kernel and puffs up when heated. As a highly popular snack, popcorn is the official state snack food of the U.S. state of Illinois (the snack was officially ratified by Governor Blagojevich in 2003.)
For their analyses, the physicists studying the popcorn process deployed high-speed cameras, capable of recording at 2,900 frames per second. According to the BBC, by playing back the footage, slowly, the scientists observed popcorn as it was heated in an oven. Running the study several times, the scientists increased the temperature at increments of 10 degrees over a period of five minutes.
Through this, it was observed that the moisture inside the corn began to turn to steam as the temperature passed 100 degrees Celsius (212 degrees Fahrenheit). As the temperature reached 180 degrees Celsius (356 degrees Fahrenheit), the pressure inside the corn rose to 10 times the atmospheric pressure at sea level. This pressure causes the outer shell of the corn to burst and the starchy inner material to rapidly expand, forming popcorn.
The outcome of this tasty research inquiry has been published in the journal Royal Society Interface. The research paper, written by Emmanuel Virot and Alexandre Ponomarenko, is titled “Popcorn: critical temperature, jump and sound.”
