Why Does Popcorn Pop? | The Science Behind Popcorn

Why Does Popcorn Pop
Why Does Popcorn Pop

Are you amazed by seeing popcorn popping? Ever wanted to know why does popcorn pop? Then read this article to find out the answer


Popcorn is also known as a whole grain food, and it represents one of the most popular snack foods.
We all love eating popcorn corn, don’t we? Have you ever thought about how popcorn pop and the science behind it? Well, this article will help you understand everything about popcorn.
Let’s go through every single component that is present inside the popcorn and how the kernel transforms into a fluffy popcorn.

Also have you got popcorn stuck in your throat and ever wondered how to get rid of it, then this article is for you: how to get a popcorn kernel out of your throat


Each kernel is made of a plant embryo, it is a starchy endosperm that feeds the embryo, and it has a hard exterior called the hull.
The popcorn’s ability to pop is based on the kernels, which contain little amount of water stored in a circle of soft starch inside the hard outer casing.
Let us briefly look at what kernel consist of:

  • Endosperm – Endosperm is a tissue produced inside the seeds of the most flowering plants following the process of double fertilization. It surrounds the embryo and provides nutrition in the form of starch though it also contains oils and protein.
  • Germ – The germ is the only living part of the kernel. It is also called the embryo. It consists of important genetic information, vitamins, enzymes, and minerals that are essential for plant growth. The germ accounts for 25 percent of corn oils, and it is a valuable part of the kernel.
  • Pericarp or hull – Pericarp is the outer covering that protects the kernel and helps to maintain the kernel’s nutrient value and moisture content. It is about 91% fiber.
  • Tip cap – The tip cap is the attachment point of the kernel to the corn cob (it is the central core of an ear of corn), where nutrients and water flow, and this is the only part that is not covered by the pericarp.
  • Starch – Starch is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds (it is one type of covalent bond that combines the carbohydrate molecule with another group). This polysaccharide (they are the most abundant carbohydrate found in food) is produced by most of the green plants for energy storage. It is the most commonly found carbohydrate in human diets. It is stored in large amounts in the type of staple foods like wheat, potatoes, maize (corn), rice.
  • Moisture – Popcorn kernels need to have a specific percent of moisture for them to pop. They need 13.5% – 14% moisture to pop successfully. The inside part, which is the soft starch, is surrounded by the kernel’s hard outer surface.

We need to keep in mind that there is a variety of corns such as:

  • Field corn
  • Sweet corn
  • Popcorn

So out of this, popcorn is the corn that pops

How and why does popcorn pop when heated?

The popcorn kernels contain oil and water with starch, surrounded by a hard outer coating. So, when popcorn is heated, the moisture inside the kernel allows it to expand, but it cannot escape through the seed coat ( the popcorn hull or pericarp). The hot oil and steam gelatinize the starch which is present inside the popcorn kernel, making it softer and flexible.
When popcorn reaches a temperature of 180C, the pressure inside the kernel is around 135 psi, which is sufficient pressure to crack the hull and to turn the kernel inside out. The pressure inside the kernel is released very quickly, and it expands the proteins and starch inside the popcorn kernel into a foam, which cools and sets into a puffy popcorn. A popped popcorn is 20 to 50 times larger than the kernel itself.
Gelatinization – Gelatinization in cooking means the gelatinization of starch in which those starch granules swell when heated.

The popping sound

If you are not sure why there is a huge popping sound while cooking popcorn, it is usually the steam that is rushing out of the kernel. Imagine when you are trying to open a soda bottle, the gas tries to escape out of it where we can hear the sound while the gas passes away.

Why do some popcorn kernels not pop?

The popcorn needs to have about 14% water for it to pop, but some kernels contain less. When a kernel doesn’t pop, it means that there wasn’t enough water for the popcorn’s starch and protein coating to expand during popping.
If you find that popcorn kernels aren’t popping and you tried to cook them for a longer time, and still it won’t pop, it could be possible that they may have gotten wet while being stored.
Sometimes, a damaged hull might be the issue because the damaged hull won’t be able to trap moisture as it will have leakage, the pressure won’t build up inside the kernel.
If the popcorn kernel becomes too dry, there won’t be any moisture left to create that pressure for popping.
The ineffective temperature could also be a reason for the kernel not to pop.


Does soaking popcorn make it pop better?

When you soak popcorn kernels in water, the seeds absorb extra moisture. This increased moisture content causes the kernels to pop slightly extra faster. It can cause some kernels to be fluffy.

Why do popcorn pop and other corn doesn’t?

Unlike other regular corn, popcorn has a non-porous (materials in which air or liquid can’t pass through) the kernel’s hull traps the steam.

How to make popcorn pop fluffy?

Soaking the kernels before cooking it can give you fluffy popcorn

Can you pop popcorn with water?

Yes, you can try with boiling water, but you won’t be able to see them pop completely but only half cooked


I hope this content helped you understand how popcorn pops and the science behind it. If you did find this article helpful, don’t forget to share it with your friends and family.

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