How Does Popcorn Pop?

My mom used to tell me a story about her upbringing on a farm. The primary crops were lots and lots of apples, sprinkled with a few peach and pear orchards. Her family also maintained a more limited vegetable field for fresh food for the family. Anyway, one year, they decided to plan a sizable field of corn. Imagine their surprise when the resulting corn was … lousy. Yep, you guessed it: somehow, the desired sweet corn seeds got mixed up with the popcorn variety. Anyone need a field of popcorn? Final score: Mom and Dad: not particularly pleased. Kids: Ecstatic. And that leads us to today’s topic: how does popcorn pop?

Pop History

Corn has been around 75 percent of forever, likely originating in the South and North Americas. Some pollen specimens dating back 80,000 years have been discovered with a striking similarity to what we find in today’s corn. Even popcorn dates back thousands of years. Preserved ears of popcorn have been found that are over 5,000 years old.

In the 17th century, European settlers were introduced to the Native Americans’ style of popcorn, cooked and popped in clay jars heated in sand. Word has it that at least some Native American tribes used the popped kernels in soup.

By the late 19th century, popcorn caught fire, pardon the pun, and became an affordable snack treat. Often served by street vendors, it made its way into movie theaters when moving pictures burst on the scene. Eventually, thanks to industry promotion, the popcorn habit arrived in the home, too. Indeed, the invention of the microwave had something to do with today’s 40+-quart-per-capita consumption of blown-up fruit-veggie-grains. Yes, you read that right: corn is a whole grain, which puts it in the veggie family, but the kernel comes from the “flower,” so it’s also a fruit. Whatever. It’s delicious.

Pop vs. Regular Corn

You might be wondering … is popcorn regular corn prepared differently or a different plant altogether?

While it’s a member of the corn family, it’s more like field or Indian Corn than the sweet corn we butter up in the summer. Four significant corn groups are Dent (field), Flint (Indian), Popcorn and Sweet. The first three have starchy kernel exteriors and are harvested after the kernels become mature and hard. Sweet corn is harvested earlier in the cycle, while the kernels are soft and yummy. That’s what we normally boil and eat. If you drop Dent, Flint or Popcorn in the pot, you’re going to not enjoy a lousy meal.

The primary difference between the two groups is that tougher, starchier exterior of the field, Indian and popcorn.

Culinary Explosion: How Popcorn Pops

By this brief explanation of the popcorn kernel, you might already be guessing how popcorn pops. The hard outer shell encloses moisture in the center of the dried kernel. When heated, the moisture turns to steam, and it begins to expand after turning to gelatinous mush. Pressure builds and eventually blows the kernel up, turning it inside out in a violent transformation.

There is some preparation involved. Tossing a freshly picked popcorn ear in a hot pan probably won’t do much. Farmers and processors strip the husks and carefully dry the popcorn cobs until there’s a remaining moisture level of about 14 percent. That’s prime popping territory. Then, kernels are removed from the cob, filtered to separate them from other corn junk, and polished to remove any excess material from the outside of the kernel. That’s why the contents of a bag of unpopped corn looks so neat and tidy.

When it arrives at your home or the neighborhood movie theater, microwaves, hot air, or a rotating hot pan raise the temperature of the kernels to around 400 degrees, and they subsequently explode, creating the basis of one of our favorite snack foods.

As for the great family farm popcorn incident? Let’s just say my mom and her siblings were well-stocked for movie nights. If they’d only planted some sarsaparilla to go with…