What Happens If You Crack Popcorn Kernels?

You may already know that the way popcorn works is that when you heat the popcorn kernels, the water inside turns to steam.

Kernel and popped popcorn

Popcorn kernel and Popped Popcorn (Photo credit: Wikipedia)

This in turn builds up enough pressure to crack the kernel and let the soft, fluffy corn inside pop out.

But, how do you prove it?

What would happen if you cracked the kernel, just a little bit, before heating it up?

Would it release the steam before popping the kernel?

Would it pop out faster?

Would it come out more slowly?

Would it be smaller?

Would it come out at all?

Here’s an experiment that helps you find out.


  • 50 kernels of popcorn
  • Vegetable oil
  • Pan with see-through lid, glass or plastic
  • 2 small bowls
  • Measuring spoons
  • Pair of pliers
  • Stove
  • Hot pad


  • Count out 25 kernels of popcorn into each of two small bowls
  • With the pliers, crack each of the kernels in one bowl. Do not crush; just apply enough pressure to hear a crack.
  • Pour one tablespoon of oil into the pan
  • Pour the bowl of cracked popcorn kernels into the pan
  • Set the pan on the stove
  • Turn the heat on under the pan to medium.

What Should Happen?

In about five minutes, the popcorn kernels should have oozed open, fluffed open a little or burned.

Using a hot pad or glove to pick up the handle of the pot, and another one to take the top off, dump the hot oil and popcorn kernels onto a paper towel on a wooden cutting board or counter.

The pot will still be very hot.

Put it on a safe surface and let it cool off for five minutes, then wash with hot, soapy water.

Repeat the experiment with the uncracked popcorn kernels.

Within about five minutes, all the kernels should be popped open and fluffy.

Why Is This Happening?

Heating the hard shell with a high starch interior combines to convert the water in the starchy corn to steam that breaks the shell and fluffs up and releases the soft interior.

Would It Work with Any Other Grains?

Theoretically, since the requirement for popping is hard-shelled grains with starchy interiors, amaranth, quinoa and millet should also pop.

As I happened to have these healthy whole grains on hand, I decided to try.

Since these grains are very small, I measured one teaspoon of each instead of counting them.

25 popcorn kernels are about one teaspoon.

And, also, because they were very small, popped kernels were very small, about the size of a grain of salt.

The results follow in the table below.

                                      Results of Heating 3 Whole Grains








4 minutes to start popping; 6 minutes toasted

2 dozen popped grains



6 minutes toasted

Shaken while cooking

No popped grains



5 minutes to start popping, 12 minutes toasted

4 dozen popped grains


I stopped when the grains that weren’t popped were toasted.

They taste like light nuts when toasted and will end up on tonight’s salad!

Thanks to thenakedscientists.com for this activity.


Carol Covin, Granny-Guru

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers

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