Have you ever wondered why popcorn pops? A popcorn kernel is a seed comprising of following four layers
- ThePericarp (outermost cover): It’s a hard outer shell
- The Endosperm: This starchy portion occupies the bulk of the kernel. Apart from starch, it is having smaller amounts of protein, fat, minerals and water. It is this water that plays a vital role in popping the popcorn.
- TheGerm (embryo): It is the half developed plantlet within the seed which later grows into a full plant.
- Tip Cap: the part where the kernel is attached to the cob.
For popping the corn, you need to heat it. When you heat the kernel is heated to about 200 degrees Celsius) the residual water (around 13-14%) stored inside the endosperm is converted into the vapor. This makes the endosperm to expand which in turn puts pressure on the hard starch present in the endosperm. Eventually, the outermost hard cover or pericarp also comes under stress and explodes (with a pop sound) flipping itself inside out letting the steam to escape. This exposes the soft white fluffy starch better known as popcorn.
It sounds easy but there are some critical factors for a popcorn to pop.
Firstly, the water concentration must be around 13-14%. It is interesting to know that while harvesting moisture content in the kernel is around 16-19%. While making the popcorn ready for popping the moisture content is reduced by drying/ curing them under controlled conditions. Too little moisture will not produce enough steam for popping and too high moisture will let the steam out prematurely and the fluffy core will not be exposed fully.
The hard outer shell should be hard enough to withstand the steam pressure upto the point where the inside starch is fully cooked and hard enough to burst the outer shell fully.
In case the pericarp is having any crack or damage the steam will escape prematurely without cooking the starch inside.
Last but not the least, the cooking temperature must be above 150 Degree Celsius. Otherwise, the total process will be incomplete.
In case you are interested, you may watch the video below showing popcorn popping in slow motion:
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Author: Technology and Beyond
