What Makes Popcorn “Pop?”

The only thing that may be more fun than eating popcorn is watching it pop. It’s fascinating to see the flurry of corn kernels exploding into a tasty snack. But have you ever wondered what exactly makes popcorn pop? And can any type of corn be used to make popcorn? Let’s explore the science behind popcorn, including why some types of corn pop and others don’t.

Can All Corn Pop?

Unfortunately, when you’re craving some popcorn, you won’t be able to shave kernels off any corn cob, heat them, and make yourself a bowl of popcorn. The only variety of corn kernels that will pop into popcorn is the zea mays everta variety. This strain of corn grows the same way any other type of corn grows, but when it’s used to produce popcorn, the cob is left to grow until it turns brown, and then it is harvested and processed to make popcorn. 

There are different types of corn, including flint corn, pod corn, dent corn, flour corn, and sweet corn. Zea mays everta is a type of flint corn. But what makes this type of popcorn pop is that zea mays everta has a non-porous hull. This difference in the makeup of the hull plays a crucial role in allowing the popcorn kernel to pop.

The Anatomy of a Popcorn Kernel

To understand what makes popcorn pop, you need to understand the anatomy of a popcorn kernel. Each kernel is made up of a hard outer layer known as the hull or pericarp. Directly under that hull are layers of hard starch known as the endosperm. The starch inside the popcorn provides food for the kernel’s germ or embryo. There is also moisture inside each kernel. For the kernel to pop, that moisture must make up about 14 to 15 percent of the kernel. Any kernels that have more or less water will not pop. 

When the kernel is heated, the moisture inside evaporates and turns to steam. The building pressure generated as the water turns into steam is held in by the non-porous hull of the popcorn kernel, allowing it to increase. Because other types of corn have a porous hull, the pressure created by the heated moisture content isn’t allowed to build up. It escapes through the hull of those types of corn, making it impossible for a build-up of pressure to pop the kernel. When the steam in a popcorn kernel reaches about 400 degrees and a pressure of about 135 PSI, it will rupture the kernel’s hull — or, in other words, the popcorn will pop. It was once thought that the hull rupturing is the sound you hear as the kernels pop, but the popping sound actually comes from steam being released into cavities in the kernels. 

As the kernel heats, the starchy layer also begins to soften. After the hull ruptures, the soft starch layers expand outward and cool. It’s these starchy layers that form the puffy parts of the popcorn. A popcorn puff is essentially a popcorn kernel that has turned inside out because of the pressure created when its water content is heated. 

Why Unpopped Kernels Didn’t Pop

This process also reveals why you might see some unpopped kernels left behind while popping corn at home. Popcorn that has been sitting in a cabinet for a long time will be less likely to pop consistently because the kernels have begun to dry out. This is why popcorn should be kept in an airtight container. Additionally, if the temperature is too high when making popcorn, the hull could rupture before the starch can soften enough to puff. But, at the same time, if the temperature is too low, the moisture content of the kernels can evaporate before the pressure inside the kernel is built up enough to rupture the hull. 

Different Types of Popcorn

Several different types of popcorn varieties are cultivated to produce an assortment of popcorn shapes, flavors, and gourmet popcorn. Mushroom popcorn is most commonly used in the flavored and coated popcorn varieties you’ll find in tasty kettle corn and gourmet popcorn gifts. This type of popcorn usually produces a round, bumpy puff ideal for coating and flavoring. When you buy caramel corn or chocolate-covered popcorn, it’s typically made with this type of popcorn. 

The large, fluffy type of popcorn commonly used to produce movie theater popcorn is known as butterfly popcorn. Butterfly popcorn kernels produce a piece of popcorn with a more irregular and less uniform shape, often with sections of puffs that are easy to break off. Popcorn flavor can still be added to these types of popcorn, such as cheddar cheese and butter, but it’s far less common to find them coated with caramel or chocolate because of their less uniform shape.

Satisfying Your Popcorn Craving

Now you know what makes popcorn pop, and after reading all about popcorn, you might now be craving some, too. Whether that craving is for traditional sweet kettlecorn, cheesy golden cheddar popcorn, or decadent chocolate-covered popcorn, Best Darn Kettlecorn has the popcorn for you. If you’re looking for the best caramel corn to buy, check out our Carmel, Caramel Nut Crunch, and Caramel Chocolate Chip varieties. Shop online today to find out why we’re known for making the best popcorn online. Our delicious gourmet popcorn will keep you coming back for more and make mouth-watering additions to gift baskets for any occasion.