Why does popcorn pop?

Contributed by: Harrison Z.


Popcorn (a type of maize that is part of the grass family) pops when the kernel is heated to around 212 degrees Fahrenheit. The heat causes the moisture in the kernel to cause so much pressure; it breaks open the airtight shell and flips inside-out. The white fluffy outer coating is actually the starch that was inside the kernel. So if this happens, how come sometimes popcorn doesn’t pop? Well moisture is an important factor in popping popcorn. The kernel must be at least 13% moisture. If it is anything below 13%, it will result in an un-popped popcorn kernel. factor that results in kernels not popping is damage to the shell. If it has even the tiniest hole in it, the shell will not be able to pop. If the shell is in good shape, it will be able to last years and still be able to pop. A 4000 year old popcorn kernel was found in bat cave, NM and still was able to pop. A popcorn kernel is made of three parts, the pericap, the endosperm, and the germ. The pericap is the tough air-tight shell, the endosperm is just carbohydrate in the form of starch and the germ is the part that shoots out and is not that important in popping a kernel. Popcorn was created by Native Americans so the process is at least 5000 years old. It was later made easier by the introduction of popcorn machines. There are two main types of popcorn. Rice popcorn, where the kernel is pointed at the front and back, and pearl popcorn, which the kernel is round and compact.Of the four main types of corn (sweet, dent,[ also known as field] flint[also known as Indian corn] and popcorn) only popcorn pops!

Figure 1- popcorn

Figure 1-popcorn

Rice Krispies. Rice can also be popped. It professional equipment and is much much harder to pop than popcorn, but when it is finished it becomes the cereal rice krispies!


Wheat. You might not know it, but wheat can also be popped. It becomes bread. It is a much slower process than popcorn, but it pops.


Fahrenheit: the temperature scale where water freezes at 32 degrees and boils at 212 degrees
Pressure: the action of a force against an opposing force
Moisture: water that is dispersed through a gas in the form of water vapor or small droplets

“How does popcorn work?” TLC cooking. 2011. Web. September 26, 2011
“Why does popcorn pop and other grains don’t.” A moment of science. 2011. Web. September 26, 2011
Wood, Robert W. Heat FUNdamentals. New York: Learning Triangle Press, 1997. Print.