Popcorn pops due to the unique internal structure of its kernels. Here's the process:
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The Kernel's Interior: A popcorn kernel consists of a hard, non-porous outer layer called the pericarp (or hull) that surrounds the starchy endosperm. The endosperm contains moisture, typically around 14-20%.
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Heating Process: When heat is applied (whether through a popcorn machine, stovetop, or microwave), the moisture inside the endosperm turns into steam.
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Pressure Build-Up: The hull's strength prevents the steam from escaping, causing pressure to build inside the kernel.
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The Pop: Once the internal pressure reaches approximately 135 psi (pounds per square inch), the hull can no longer contain it and ruptures.
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Expansion and Cooling: This sudden release of pressure causes the starchy endosperm to explode and expand rapidly. The steam is released, and the starch cools and solidifies, forming the familiar fluffy popcorn shape. The kernel can expand to 20 to 50 times its original size.
In essence, popcorn "making" (the popping process) isn't about manufacturing the corn itself, but about applying heat to a special type of corn kernel that has the right moisture content and a strong hull that allows it to pop.
