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The Deal

• $10 for $20 worth of gourmet popcorn

Popcorn: Edible Explosives

There are many varieties of corn, but only one has a husk capable of creating a delicious pop. Groupon made a study of the starchy snack to tell you how it happens.

Popcorn may end up as a deliciously benign treat, but it only gets that way as a result of a catastrophic process—one that mimics the rupture of an exploding water boiler or gas tank. Each kernel’s hull contains starch and a little bit of water, the latter of which expands as it’s heated. Once the internal temperature reaches around 450 degrees, the water becomes steam, creating intense pressure. This pressure builds and builds until—POP!—the kernel explodes with enough force to turn itself inside out, expanding to 40–50 times its original size. The starch solidifies into the familiar fluffy shape, and—aside from getting topped with butter or strung together to feed a Christmas tree’s squirrels—the corn’s transformation is complete. Not all kernels have sufficient moisture content to burst, however, which is why almost any bag, carton, or tub of popcorn includes at least a handful of unpopped kernels at the bottom.

Popcorn has been erupting for centuries, if not millennia, and methods of popping have evolved over the years. Early popcorn enthusiasts brought corn to the desired temperature by mixing kernels with sand that had been heated in a fire. Cooking approaches evolved with technology, but it wasn’t until the late 19th century that portable poppers made it possible for vendors to travel with crowds, stoking demand for a crunchy snack.