Have you ever wondered how popcorn pops? There is actually a popping mechanism, and unless you’ve bothered to watch it pop with a special type of camera, there is a good chance that you don’t know how it works. Although it might seem mysterious, the popping process is actually very simple.
How Popcorn Pops
It’s important to understand that every kernel contains oil and moisture. Popcorn is actually a type of grain, but it’s different from other grains because it has a hull that is both impervious to moisture and very strong.
Also, the starch found inside of the hull is made almost exclusively of very dense material. So, what happens when you apply heat? When intense heat is applied to the kernels, the water and oil around the hull cause the moisture inside of the kernel to transform into a pressurized and superheated steam.
These extreme conditions cause the starch inside of the kernel to soften and gelatinize, which forces the kernel to become pliable. As pressure continues to build, the hull will eventually reach its breaking point.
This level of pressure ends up being about 135 PSI, and the temperature rises to about 180 degrees Celsius. The kernel’s hull ends up rupturing, and the rupture process takes place extremely rapidly, which causes a massive release of pressure from the inside of the kernel.
As the hull ruptures, the proteins and starch also expands rapidly, and this result is airy foam, which ends up being the fluffy white part that we all know and love. The reason why the starchy mixture goes from liquid to the fluffy material is because it cools very rapidly. There are some varieties that are made for improved yield.
The Expansion Process and Yield
Although this title might sound slightly boring, it’s really an interesting process. The popping results that you get from a batch are dependent on how quickly the kernels are heated.
If you were to heat the kernels too quickly, it would cause the hull to rupture before the starch in the center of the kernel has a chance to gelatinize. This results in kernels that are only partially popped and hard centers.
However, if you heat the kernels too slowly, you’ll basically end up with un-popped kernels. Whoever said popping the stuff isn’t hard work! When you heat kernels too slowly, steam can escape out of a tiny opening in the tip before it ever has a chance to build up enough to rupture the hull.
How to Determine Quality?
Have you ever wondered what sets OK product apart from GREAT popcorn? The two major factors that are used to determine quality is the percentage of kernels that actually pop and how much each kernel expands. Both vendors and consumers should care about how much kernels are able to expand. Consumers like bigger pieces because they’re normally a lot more tender and tasty than smaller kernels that have minimal expansion.
Vendors, distributors and growers care about how much kernels expand because it affects their profits. An establishment like your favorite movie theater purchases kernels based on their weight and sells the finished product based on volume.
For example, the theater sells small, medium and large tubs, and this type of pricing is based on volume, so it makes sense why establishments like movie theaters and circuses care about kernel expansion. It’s possible to make it pop if it has been freshly harvested, but unfortunately, it doesn’t pop well.
The high moisture content in freshly harvested product doesn’t produce great expansion and causes the finished product to be chewy. All kernels that have very high moisture content are vulnerable to mold growth. This is why distributors and growers dry their product until it reaches the ideal moisture content that guarantees great expansion.
Most growers aim to sell their product when it reaches a moisture content of about 15 percent by weight. However, it’s possible for kernels to become too dry, and like too much moisture content, a kernel that doesn’t have enough moisture content will not pop very well.
In the industry, the leftover kernels that don’t pop when you apply heat to them are called old maids. These kernels normally don’t pop because they simply don’t have enough moisture content in them. Kernels that don’t have enough moisture in them can be hydrated before popping, which almost guarantees they will pop.