Wednesday, July 20, 2011

Biochemical curiosity

The "explosion" of a grain of corn when heated is the result of the combination of three characteristics:
1. The interior of the grain (endosperm) contains, in addition to starch, about 14% water.
2. The endosperm is an excellent conductor of heat.
3. The exterior of the grain (pericarp) has great strength and rarely had flaws (cracks).
When corn is intensely heated, the water in the endosperm undergoes vaporization, creating a high pressure steam within the grain. The pericarp acts like a pressure cooker, avoiding the exit of water vapor up to a certain pressure threshold is reached. At this point, two things occur: the grain explodes, with its characteristic sound (POP!) and starchy endosperm swells abruptly, creating the soft texture.

And even now, did you know that there are no two exactly equal popcorns?

Source: Revista QMC Web

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