Why do popcorns pop?

A popcorn kernel is a unique type of corn seed. Unlike other corn kernels, popcorn holds the magic of transformation thanks to its unique structure. This small kernel holds the secret to one of the most delightful snacks, thanks to its unique structure and composition.

• The hard outer shell- pericarp
• Fluffy white part- the endosperm which is the starchy interior
• And, the germ- a tiny seed embryo within the kernel

The tough outer shell and specific moisture content set popcorn apart from other corn types. The pericarp’s strength and the endosperm’s starch type are crucial for the popping process.

The role of water and heat

Maybe you don’t think about it while enjoying a bowl of cheesy or caramel popcorn, but there’s a surprising secret hidden inside each kernel. Water and heat play a crucial role in the making of those tiny seeds into the delicious snacks we love.

Moisture content

For optimal popping, popcorn kernels must contain about 13-14% moisture. This precise amount of water inside each kernel is critical. If the moisture content is too low, the kernels won’t generate enough steam to pop, resulting in a lot of unpopped kernels. If it’s too high, the kernels may burst prematurely, leading to smaller, less fluffy popcorn.

Heating process

When popcorn kernels are heated, the water inside the kernel begins to turn into steam. This process typically requires a temperature around 180°C. As the temperature rises, the water molecules inside the kernel move faster and faster, creating increasing pressure within the kernel.

This pressure continues to build until it exceeds the strength of the pericarp (the tough outer shell). At this critical point, the kernel bursts open, rapidly expanding and turning inside out to form the light and airy popcorn we enjoy.

The science behind the pop

The secret to the pop lies in that tiny drop of water inside the kernel. When you heat the kernel, the water gets hot too. But instead of just getting hotter, it changes completely – it turns into steam. This steam takes up much more space than the water did.

The hard outer shell of the kernel acts like a lid, trapping all that steam inside. As the steam gets stronger and stronger, it pushes against the shell. Finally, with a pop, the pressure becomes too much and the shell bursts open!

The burst releases all the steam, and in the rush, it takes the starchy centre with it. As the steam escapes and cools down quickly, the starchy centre puffs up and solidifies, turning into the fluffy white popcorn we enjoy.