Pop goes the kernel

One of my favorite activities involves seeds and plants and visiting second-graders from the Jim Thorpe Area School District. Our entire day is focused on the importance of seeds and plants.

During my activity, each part of the seed is explored to learn what its purpose is. At the end of the activity I tell the boys and girls we are going to explode some seeds. And then we are going to eat those exploded seeds. Which sounds really exciting, doesn’t it? I mean, who doesn’t enjoying exploding something once in a while? Of course, “exploding” popcorn kernels isn’t as chaotic as it sounds! I like to eavesdrop as the students try to figure out what kinds of seeds “explode” that we are going to explode and eat.

If you are anything like me, you haven’t really given popcorn kernels too much thought, but after doing this activity over the years, and after explaining to children that no other seeds “explode,” I became rather curious about corn and wanted to learn a little more about this common grain. And I learned a few things I never knew.

There are four main types of corn: field, sweet, decorative and popcorn. I thought that all corn was sort of the same, but that’s not the case. Each type of corn has its own distinguishing traits and uses. You can’t pop sweet corn, and you wouldn’t want to eat boiled field corn.

Sweet corn is what comes to mind when we think of corn on the cob. It is almost all soft starch and will never pop. It contains more sugar than other types of corn, and unlike other corn types that are picked when the kernels are dry and mature, sweet corn is picked and eaten while the ears are in the milk stage and the kernels are tender.

Dent corn, or field corn, is widely grown in the U.S. It is used for livestock feed, but it is also used in some food products. It contains a mix of hard and soft starches that become indented once the corn is dried.

Flint corn is “Indian corn” and is distinguished by its wide range of colors and grown mostly in Central and South America for decoration in the fall. Flint corn is one of the oldest varieties of corn that Native Americans taught the early colonists how to cultivate. Its kernels, which come in a range of colors including white, blue and red, have “hard as flint” shells, giving this type of corn its name. Despite its tough exterior, this type of corn can be consumed by livestock and humans, and is used in such dishes as hominy (grits) and polenta.

Popcorn is a type of flint corn but has a hard exterior shell or “seed coat” and a soft starchy center. When heated, the natural moisture inside the kernel turns to steam and builds up enough pressure to split the seed coat and the kernel “explodes.” Other types of dried corn may burst open slightly when heated, but not like popcorn. Popcorn is unique in its taste and “popability.”

Early Native Americans believed a spirit lived inside each kernel of popcorn. The spirits wouldn’t usually bother humans, but if their homes were heated, they would get angrier and angrier, until eventually they would burst out of their homes, and flee into the air as disgruntled puffs of steam.

I have a less charming but more scientific explanation for why popcorn “pops.” Popcorn is different from other types of corn because the seed coat has just the right thickness to allow it to burst open.

As the kernel heats up, the water begins to boil, and at 212 degrees the water turns into steam. As the kernel continues to heat to about 347 degrees, the pressure inside the kernel will reach 135 pounds per square inch before finally bursting the hull open.

As it explodes, steam inside the kernel is released. The soft starch inside the popcorn spills out, cooling immediately and forming into the odd shape we know and crave.

A single kernel can swell to 40-50 times its original size and pops with such force that it can be propelled up to 3 feet in the air. I know this for a fact! My 38-year-old air popper has had those last few popping kernels explode into the bowl rather forcefully, causing them to bounce out and into the air in an astonishing display.

The schoolchildren stare as the “exploding” popcorn kernels come out of the popper and into the bowl. Comments from “Wow!” “That’s so cool!” and “I never knew popcorn could do that!” make the lesson all the more enjoyable knowing that kids can still be excited by a few simple activities.

All this writing about popcorn has me thinking about making some popcorn and watching a scary movie.

The Carbon County Environmental Education Center is located at 151 E. White Bear Drive, Summit Hill.