It’s movie night!
And no matter what you watch, there’s one snack that goes with any kind of film.
Popcorn!
But here’s a curious question: Why does popcorn pop?
Why does popcorn pop?
First, let’s take a look at a piece of un-popped corn, called a kernel.
kernel
A kernel is actually a seed of the popcorn plant – so if you planted one, it could grow into a whole new popcorn plant!
The kernel’s hard outer shell is filled with a soft, white substance called starch.
starch
This starch contains a small amount of liquid water.
When the kernel is heated, the starch becomes hot and gooey, and the liquid water turns into a gas – steam.
The steam tries to escape, but is trapped by the kernel’s shell.
Pressure starts to build up until eventually, the shell cracks and pops open.
In a split second, the starch bursts out, and hardens to form the familiar, puffed-up popcorn shape!
There are many different types of corn.
But only one of them produces kernels with the right amount of water in the starch and the right thickness of shell to pop in this way.
So that’s why popcorn pops:
When heated, liquid water inside the kernel turns into steam.
Pressure builds up, causing the shell to crack.
The starch bursts out, and hardens to form a fluffy piece of popcorn!
Got it? Great – another curious question answered!