Apple #434: Popcorn

I've been liking the popcorn lately.  I don't mean the microwave kind, I mean the kind you heat up in a pot and pop yourself.  Melt the butter and pour it on top, add the salt, and yum.


Bowl of crunchy salty deliciousness that is popcorn.
(Photo from Start Up Blog)

• There are four types of corn that are the most common:

1. sweet (the kind you eat on the cob)
2. field
3. flint (a.k.a. Indian corn)
4. popcorn

• Only popcorn will pop.

• The reason that popcorn does pop and the others don't is that its hull, or outer coating, has the right thickness to burst open when heated.

• Inside the hull is a soft circle of starch.  Inside that circle is a drop of water.   

• I find this espeically interesting, since the way popcorn is harvested, it's allowed to dry in the field.  It isn't even picked until the husks are dry and the kernels are hard.  Then it's packaged and shipped and stored in the grocery and then on your self.  But still, that drop of water remains in the kernel.  

Diagram of a kernel of corn.  The pericarp is the hull.  The germ, I believe, is the starchy part, and the necessary drop of water is inside there.
(Diagram from Democratic Underground)

• When the corn is heated, so is that water deep inside the starch.  The starch begins to soften, and the water expands.  At 212 F, the water turns to steam.  You'd think the kernel would pop here, but no.  The suspense continues. The temperature rises still higher and the steam is going berserk in there, and the pressure inside the starch -- which is now gelatinous -- continues to build.  

• When the pressure inside the grain hits 135 pounds per square inch, then the hull bursts open.  The steam inside the kernel is released, and the soft starch spills out and cools as soon as it hits the air to form that oddball shape we all know and love as popcorn.

Step by step photo of a kernel of popcorn popping
(Image from the Popcorn Board)

• You can watch a slow-motion video of kernels of popcorn popping at the Popcorn Board's website.  It's close up and slow enough, you can see the water escaping as the hull bursts open and the starch expands to turn the whole thing nearly inside out.

• Popcorn was first grown in Mexico.  It was a big part of Aztec culture.  They used popcorn in ceremonial headdresses that they wore during special dance ceremonies, and they made it into necklaces and put them on the statues of their gods.

• The Aztecs's word for popcorn was "momochitl."  The Incas in Peru apparently liked popcorn too.  They called it "pisancalla."

• The Iroquois who lived along the Great Lakes also made popcorn.  They served French explorers who visited them popcorn soup and popcorn beer.
  

• In fact, lots of native people throughout the Americas grew and ate popcorn.  Somehow -- no one seems to be sure how -- people in China and India and Sumatra started growing popcorn after the Aztecs did but before any Europeans showed up in the Americas and found out about popcorn (among other things).

• European colonists liked popcorn so much they ate it with sugar and cream for breakfast.  Technically, this makes popcorn the first puffed breakfast cereal.

• In more recent history, popcorn first became popular in the U.S. when corn was plowed on a widespread scale in the 1800s.  

• But it really took off during World War II when sugar was scarce.  People ate more popcorn as a substitute for sweets, and it became the snack to eat at the movies.

To this day, popcorn remains the quintessential movie-going snack.
(Photo from Your Big Fat Boyfriend)

• In the 1950s when people stayed home to watch TV instead of going to the movies, people also ate less popcorn.

• But then, with the advent of microwave popcorn in the 1990s, it surged back to popularity again.

• The very first use of microwave heating was to make popcorn.  In fact, popcorn was what the microwave's developer, Percy Spencer, used for many of his initial tests.  This took place longer ago than you might think: the 1940s.

• I suspect popcorn is one of those foods about which nutritionists would say, "It's not the popcorn, it's what we do to it that's bad."  I'll show you what I mean.

• Popcorn, air popped, 1 cup: 31 calories, 0.4g fat
• Popcorn, oil popped, 1 cup: 64 calories, 4.8g fat
  
• Pop Secret Butter microwave popcorn, 1 cup: 960 calories, 64g fat
• Movie popcorn, medium (15 cups), no butter: 951 calories, 58g fat
• Movie popcorn, medium (15 cups), plus butter-like liquid: same as above plus 130 calories, 14g fat per pump

• So actually, movie popcorn without butter has fewer calories and fat than microwave popcorn.  But once you add the hot liquid butter-like deliciousness, it's all over.

• If you want to find out how your favorite popcorn product stacks up, check out this page at calorie count.

• If you want to pop the corn yourself (I think it tastes the best this way), here's how.  It looks like a lot of steps, but I'm being super-specific for those youngsters who may never have had popcorn at home any other way except microwaved.
  

• Use a 3- to 4-quart pot with a lid

• Heat the pot and pour in about 1/3 cup of vegetable oil per cup of kernels.  If you're making enough for one person, that's about enough oil to make a sizable circle on the bottom of the pot, but it won't cover the entire floor of the pot.

• As far as what oil to use, I've tried corn oil and olive oil.  Corn oil works a little better because it's heating temperature seems to be closer to that of the kernels.

• Get the oil good and hot. When you see pinpricks starting to form in the oil, that's a sign that it's ready to go. If you want to test it first, drop a single kernel or two into the oil.  When that test kernel pops, pour in the rest of the kernels.

• About one ounce of unpopped kernels yields one quart of popcorn.  In other words, it doesn't take as many kernels as you might think to make a big bowl of popcorn.

• Put the cover on and give the pot a shake to coat the kernels with oil.  

• You're supposed to keep the lid slightly ajar to allow the steam to escape, but most pot covers don't make a tight seal so that happens anyway without even trying.  But if your popcorn turns out soggy, that's because not enough steam escaped during the popping process.

I've seen several pots like this with fancy lids and handles which I don't know what the heck they're for.  That pot you boil spaghetti in -- get that and get out the lid.  That's all you need.
(Photo posted at Soda Head)

• I like to keep shaking every few seconds or so to make sure the kernels don't get too lazy in there and burn instead of popping.

• You'll hear the kernels pop, and you'll also be able to feel the impact of them hitting the inside of the pot.

• When the pace of the popping slows, you can turn off the heat and take the pot off the stove. Don't remove the cover though, because more kernels will still pop in there.

• I like to continue shaking the pot all the way through this process, again, to avoid burning any of the popped kernels.

• After about 30 seconds to a minute longer, the ones that are going to pop probably have, and you can pour them out into a bowl.

• Add butter & salt to your pleasure.

• There always seem to be some kernels that don't pop.  I thought this meant they were old or stale or something, but all it means is the drop of water inside the kernel has finally dried up.

• To re-hydrate the unpopped kernels, save them until you have about 1.5 cups worth.  Then put them in a jar that has a lid with about one teaspoon of water, and screw on the lid.  Make sure it's airtight.  Give the jar a few shakes every couple minutes or so until the popcorn has absorbed all the water.  Then let store them in that jar for about four or five days.  They should be ready to pop.  

• You could also make popcorn by any of these old methods used by native and colonial Americans:

• Put it on hot stones surrounding a fiercely burning campfire.  When the popcorn explodes and shoots off in all directions, you have to dive for it to catch it and eat it.  Makes a great game.

• Put it in an earthen pot and put the pot in a hole of heated sand.

• Shove a stick through a cob of popping corn and pop it while it's still on the cob.

• Put the kernels in a mesh basket with a long handle and heat it over an open campfire.

• Make a closed cylinder of sheet metal, pour the kernels into that, and turn it on an axle in front of the fireplace.
  

• Fill a kettle with lard and pour the kernels into the lard.  Skim kernels off the top of the lard as they surface during popping.

• String the kernels on a tassel (this has got to take some serious needle-work), and boil the tassels in oil.
  

• Pour it into 8-foot wide clay pots called ollas and heat the ollas in great mound-like ovens.

Some companies that make themselves look old-timey, like this one, sell popcorn on the cob.  This company, Victorian Trading Company, will sell you five cobs for $19.95.  Plus shipping & handling, I'm sure.


Of course there's also Jiffy Pop.  Which, though it looked exciting, unfortunately never worked as well as the regular old pot on the stove.
(Photo is supposedly somewhere on this chat page from Free Republic)


Sources
The Popcorn Board, Encyclopedia Popcornica
Iowa State University, Horticulture & Home Pest News, Growing, Harvesting, and Storing Popcorn, July 21, 2000
essortment, What is the history of popcorn?
Rosson House Museum, Popcorn in 19th and 20th Century America
Linda Stradley, What's Cooking America, History and Legends of Popcorn (she claims copyright to a lot of information that's widely available elsewhere)
Paramount Concession Suppliers, Popcorn History
Calorie Count, popcorn
Your Big Fat Boyfriend, Date Smart: At the Movies