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Why Popcorn Pop Sound - For decades many food lovers have grappled with the question of why popcorn makes that popping sound. Now a new study claims to have solved the mystery.
The study was published on Wednesday in the Journal of the Royal Society Interface by French engineers Emmanuel Virot and Alexandre Ponomarenko.
They arrived at their findings by using high speed cameras recording at 2,900 frames per second, along with sound recordings and the theory of thermodynamics.
Researchers discovered that "popcorn bursts open, jumps and emits a 'pop' sound in some hundredths of a second."
"By synchronizing video recordings with acoustic recordings, we propose that the familiar 'pop sound' of the pop corn is caused by the release of water vapor."
Popcorn kernels contain about 14% water, and at a 100 C it vaporizes and some of the moisture trapped inside starts to turn into steam. However, it doesn't pop till it reaches the breaking point.
Regardless of the grain, popcorn kernels will pop at a temperature of 180C as vapor is expelled. The inner cavity acts as an 'acoustic resonator' which results in the 'pop sound'.
"We found that the critical temperature is about 180 C, regardless of the size or shape of the grain," said Virot, an aeronautical engineer at the Ecole Polytechnique.
Researchers also found that before the 'pop' the popcorn kernel forms a 'leg' of starch with which it jumps like an animal or an acrobat somersaulting.
"A piece of popcorn has a singular way of jumping, midway between explosive plants such as impatiens, and muscle-based animals such as human beings, " the research read.
The popcorn pop sound is made from the release of vapor in the same way volcanoes erupt and champagne corks pop.