Sunday, February 15, 2009

Why popcorn pops

By Viliam Kanis

Have you ever wondered how those corn kernels turn into popcorn? Like the name suggests, popcorn is simply corn kernels that have popped through heating and converted into popcorn.

When corn is cut off the cob, it is stored and preserved. Each kernel has a little water or moisture locked inside of them. So when you start to heat the popcorn the pressure builds up inside the corn to the point where it has no where to go. The moisture inside the kernel converts into steam and the pressure increases exponentially. The pressure builds up and the starch starts to expand to the point where the kernel explodes. This explosion gives birth to the tasty treat we call popcorn.

Large, tender and tasty popcorn is in demand. How do we guarantee our corn kernel produces these tasty treats? Unfortunately this is out of hands and the responsibility is squarely placed on the farmers.

Farmers that grow corn usually harvest their crop when the moisture content of the corn is approximately 16-20%. Once the corn is harvested, the farmer then dries the corn until the moisture content reaches 12-15% of its body mass.

Not every corn pops. Different conr means different moisture content. Little or no water content will result in no popcorn. popcorn is formed through the expansion of water into gas which increases the pressure in the corn. The pressure needs to be released which subsequently gives birth to the tasty popcorn.

The anatomy of the corn kernel is quite simple. The corn kernel contains 3 main parts which play a significant role in the production of popcorn. The pericarp, which is the hull or simply the outer covering, the germ which is the part that sprouts and the endosperm which contains the starch that expands.

So how does the popcorn withstand the build up of pressure? Pericarp is strong and acts as a cover of the corn kernel. This strong, protective layer acts like a seal, just like a sealed plastic bag would inflate when micro waved. The steam within this cover builds up to the point where it expands and eventually explodes. Prior to heating or cooking, if the pericarp has been cut or damaged the steam will be vented resulting in no popcorn.

The expansion or popping of the corn takes place in the tightly packed endosperm. Endosperm development determines the dimension and also taste of the popcorn. The shell of the corn explodes after the inner pressure exceeds about 9 athmospheres. The gelatinized starch granules found in the endosperm do not explode, but expand into the cooler room temperature and solidify into the thin, fluffy like bubbles that we call popcorn.

Different varieties of corn have been genetically engineered for the purpose of producing popcorn. The white hull-less and yellow hull-less are the most common and are usually packaged in the microwave bags. Any corn kernels that can preserve and contain 10-15% moisture content are suitable for producing popcorn.

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