Have you ever wondered how popcorn pops?  It all has to do with the corn kernel’s hard outer shell. In this article, we’ll take a close look at why popcorn pops plus lots of other interesting facts about the world’s favorite snack!

What makes popcorn pop?

A tiny droplet of water is housed inside the kernel which gets heated during cooking. This liquid turns into steam, causing it to expand. Soft starch that protects the water turns into a jelly-like substance. As the kernel continues to heat up, the hull bursts open due to the extreme pressure. During the explosion, the soft starch inflates and immediately cools, creating popped popcorn.

Moisture levels in the grain must be 13.5-14% to pop. Anything less and the corn won’t pop. You can test this by placing some unpopped kernels in the oven on low heat for an hour. Drying out the kernel will stop any popping action. Test it for yourself.

To pop, the kernels need to be heated to 347° F (175°C). At this point, the internal pressure will reach 135 pounds per square inch, causing the hull to burst open.

The stages of popcorn popping

Stages of popcorn popping

1. Raw Kernel

One tiny droplet of water and some soft starch core is encased within the tough hull of the kernel.

2. Steam pressure

Heat from the cooking process turns the water inside to steam which can’t escape the dense hull.

3. Bursting Hull

Steam creates intense pressure inside the kernel which causes the hull to burst. The popping sound is gas escaping.

4. Propulsion

The kernel gets jettisoned as the cooked starch explodes from the hull.

5. Starch explosion

Steam force causes the starch interior to greatly increase in size.

6. Edible Popcorn

In a fraction of a second, the starch sets and the resulting white texture is crisp and delicious.

3 reasons popcorn doesn’t pop

There’s nothing worse than unpopped popcorn. Accidentally stick one in your mouth and the result could be a broken tooth. The unpopped grains are referred to as old maids or spinsters. Good quality popcorn will usually pop 98% of the bag and the remaining 2% will be spinsters.

  1. Lack of water: Within the kernel, water is necessary to create steam which builds pressure and causes the kernel’s explosion.
  2. Damaged shell: If the shell is cracked, damaged, or isn’t hard enough, the pressure can easily be released before popping.
  3. Lack of starch: The kernel must contain a starchy center. If the popcorn kernel lacks this starch due to age, quality, or genetic reasons it won’t pop.
Unpopped popcorn
Unpopped kernels are commonly called spinsters or old maids.

Nutrition Breakdown of Popcorn

Unflavored popcorn has good nutritional value for a snack. It’s high in protein, minerals, and vitamins as well as fiber and antioxidants. Adding butter, sugar, and other toppings will increase the carbohydrates and fat.

Air popped (one cup)Nutrition
Saturated Fat0g

Does popcorn go bad?

To get the best shelf life out of popcorn store it in an airtight bag out of direct sunlight and away from heat sources such as the stove. A pantry or cupboard are both excellent options, whether the popcorn is unpopped or popped.

Type of popcornShelf life in pantry
Unopened, unpoppedIndefinitely
Unopened, popped2-3 weeks

Next time you’re putting together a survival kit with food to last through a long-term disaster, be sure to add popcorn. It’s a robust food that won’t get eaten by vermin thanks to its ultra-hard exterior.

Choosing the best popcorn

Popcorn kernels all look the same in their bag, no matter what brand you choose. But we researched the mainstream brands and found the quality of popcorn varies more than you may think.

Successful popping often comes down to the hardness of the outer shell. Popcorn kernels need to withstand heat so that the starch can cook before popping. Also, if you’re cooking popcorn with oil, grains that absorb the oil prematurely will result in undersized, unpleasant popcorn.

The ideal kernel will have a round shape that encourages even cooking. Oval or elongated kernels usually produce a higher number of unpopped and overcooked popcorn pieces.

Are you looking for a trusted popcorn brand that has been producing non-GMO certified products for decades? We recommend trying Orville Redenbacher’s Gourmet Popcorn as an affordable option. The large jug format is not only economical, but it’s also convenient and easy to use. No more spilling kernels everywhere thanks to this innovative packaging. Best of all, their kernels are top quality and there are very few leftover hard kernels.

When you’ve finished making popcorn, the jug fits conveniently into the cupboard for next time.

Tips for cooking perfect popcorn

1. Use a deep pan

A popular method for cooking popcorn is to use a deep pan with oil. It isn’t as quick as using a microwave but the results are better. There’s also something satisfying about listening to the corn popping into the lid of the pan.

2. Leave the lid slightly off

During cooking, leave the lid slightly off the pan so that the steam can escape. Steaming them will produce slightly soggy popcorn without that delicious crispy texture.

3. Choose the right oil

Use an oil variety with a high smoke point so that it can withstand the high heat without burning. Oils such as olive and unrefined flaxseed oil will turn black and leave an unpleasant taste on your food. Vegetable, canola, peanut, safflower, and avocado oil are your best options. They can handle temperatures above 400F.

4. Add salt to the pan

For salted popcorn, add the salt to the oil rather than adding it at the end. This provides an even coating of salt over all the popcorn.

Recommended microwave popcorn popper

The Salbree Microwave Popcorn Popper is a simple, yet effective option for cooking perfect popcorn every time. You can buy kernels in bulk to save money and reduce the impact of packaging on the environment.

It is a fantastic tool because the unit collapses after use so it uses up virtually no space in the cupboard! This popper is also made of silicone so you’ll get years of use out of it.


  • Makes popcorn that is cooked to perfection.
  • A wide range of colors to choose from.
  • An easy-to-use kitchen tool that takes up minimal space in the cupboard.
  • BPA-free silicone materials are durable and dishwasher safe.
  • A set of handles make it easy to shake through the salt or other seasoning.


  • Requires some experimentation to establish the correct cooking time.
  • Hand washing can be a bit tricky as it folds up when trying to clean it.

Fast Facts

  • The corn kernel is made up of four parts: internal germ, endosperm, pericarp (outer shell), and tip cap.
  • Popcorn is a special kind of flint corn, also known as Indian corn.
  • In the United States, around 70% of all popcorn is eaten at home.
  • Other varieties of kernel such as sweet corn, field, flour, and pod will not pop.
  • Popcorn’s scientific name is Zea mays everta; it comes from a type of wild grass and is classed as a cereal grain.
  • Popcorn is America’s favorite snack by volume.

Final Words

When it comes to snack food, popcorn is hugely popular in the United States and many other countries around the world. Kids love listening to the kernels popping, as they transform into a delicious and nutritious snack.

The science behind how popcorn pops is remarkable: as the internal moisture content gets heated, the pressure inside builds, causing the hull to burst and the soft starch inside to expand into popcorn. This explosive chemistry can result in the original grain expanding by up to 40 times its original size!

If you enjoyed this article, be sure to check out our awesome guide to making ice cream or discover the many different types of donuts that exist in this world.

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