Why Popcorns Pop?

Everybody loves popcorn. Its smooth texture, crispiness makes us crave for more. Apart from being a snack, Popped corn is used in many decorative and experimental applications too. As its name suggests, 'popcorn' if made out of corn. Corn is heated up slowly until they pop out these 'flakes'. This happens because..


Corn seeds contains a small amount of water inside. When they are heated, water becomes steam and tries to expand. But, because the shell(hull) is thick and sealed, steam is trapped and built up inside. With rising temperature, inside behaves like a pressure cooker and melts the starch, protein and fibre in it. Pressure rises until the hull is cracked open. The molten kernel is pushed out of the hull and expands rapidly, releasing the pressure built in. As they expose to the colder air outside, they cool down returning to solid state. This process gives the characteristic shape, texture and crispiness of a flake. Plus, Corn does have some oil in it, so oil may influence the shape and the flavour of flakes as well.

Required Factors For Popping

For popping (also called puffing) to happen, Typically these factors should be met.
  1. Hard, sealed, water impermeable shell
  2. Some water content inside the seed
  3. Starchy kernel

Other Varieties/Types of Grains That Pop

Puffed Rice

This sort of popping is not limited to corn(Maize). Several other grass varieties(Yes, corn is a grass) can pop under similar conditions.

Examples:

• Amaranth varieties
• Rice
• Wild Rice
• Wheat

See more on Puffable Foods on wikipedia

But, none of them pop as good as corn. This is because their hulls aren't sealed as tight.

References

Popcorn; Popping Mechanism
Why Popcorns Pop
How Popcorns Pop