Why does corn pop?

In this guide, we will address and answer the query, “why does corn pop?” and answer other similar related questions like “What factors influence the ‘pop’ of the popcorn?” and “Why does popcorn turn white after it pops?”

why does corn pop?

The kernels of popcorn contain water. When the kernels are heated, the water inside them turns to steam. The pressure from the steam causes the kernels to explode and turn inside out, creating the popcorn.

The water in the kernel is what causes a build-up of steam building up pressure that finally makes the corn explode.

What is the composition of the corn kernel?

Let’s look at the make-up of a kernel to understand why the corn pops. Corn is generally made up of layers, the pericarp, the endosperm, and the germ.

The composition of sweet corn kernels varies depending on the variety of corn, but all sweet corn kernels contain approximately the same amount of water, starch, sugar, protein, and fiber. 

Water: Sweet corn kernels are about 80% water. This is what mainly contributes to the pressure build-up that causes the kernel to explode.

Sweet corn kernels contain about 10% starch. Sweet corn kernels contain about 9% sugar. Sweet corn kernels contain about 1% fiber.

 Lastly, Sweet corn kernels contain small amounts of vitamins and minerals, including phosphorus, potassium, folic acid, vitamin B6, niacin, thiamin, and vitamin C.

What factors influences the ‘pop’ of the popcorn?

The amount of water in the kernel, the amount of heat, the type of kernel, and the presence of any chemicals on the kernel can all affect how well the kernel pops.

The amount of hull strength also affects the top of the popcorn in two ways. First, it affects the amount of pressure that builds up inside the kernel. The more pressure that builds up, the more forcefully the popcorn will explode. 

Second, it affects the size and strength of the popcorn kernel. A strong hull will result in larger, stronger popcorn kernels that will pop more evenly and forcefully.

Heat. Heating up popcorn means that all components are being heated most especially water which occupies 80% of the total components. As the heat builds up, the water starts to evaporate.

 As the moisture evaporates, the water changes state from liquid to gas and become steam. The steam now begins to build up to a point that the kernel cannot hold anymore and the kernel therefore explodes.

Why does popcorn turn white after it pops?

The popcorn turns white because the water inside the kernels turns to steam and expands. The pressure from the steam causes the kernels to explode and the popcorn to turn white. 

Another reason why popcorn turns white after it pops is because the starch inside the kernels gelatinizes and turns white. This happens when the kernels are heated to a high enough temperature.

Lastly, the popcorn may turn white due to the Maillard Reaction. This is a chemical reaction that occurs between the sugars and amino acids in the popcorn. This reaction creates new flavor compounds and causes the popcorn to turn brown or white.

Is it healthy to eat popcorn?

Yes, popcorn is a healthy snack because it is a whole grain. Whole grains are a good source of fiber, which can help with digestion and may even reduce the risk of some chronic diseases such as heart disease and type 2 diabetes.

 Additionally, popcorn is relatively low in calories and fat, making it a relatively healthy snack option when compared to other unhealthy alternatives such as chips or candy.

Why does unpopped corn have a dark spot at the center?

The dark spots on unpopped corn are usually caused by impurities in the kernel. These impurities can be anything from dirt to rocks and even insects. The impurities absorb heat from the popcorn kernel, causing the kernel to darken.

The other reason why unpopped corn may have dark spots is because of the way it was stored. If the kernels were stored in a humid environment, they may start to grow mold. This mold will cause the kernels to darken.

If you notice any dark spots on your unpopped corn, you should discard the kernels. Eating kernels with impurities or mold can cause sickness.

For more details on how to make perfect popcorn. Click here.


In this brief guide, we have addressed the query, “why does corn pop?”  We have also discussed, “Why does unpopped corn have a dark spot at the center?” and “Why does popcorn turn white after it pops?”

Hope you found this blog useful, if you have any questions, please let us know



Hi, I am Charlotte, I love cooking and in my previous life, I was a chef. I bring some of my experience to the recipes on this hub and answer your food questions.