It’s a corny time of year, this pause between summer and fall, what with all the fresh-picked local corn around. (Eat it quickly — half its natural sugar can turn to starch within 24 hours.) Then there are all the earnest “spirit-of” festivals and fairs and their incumbent corn dogs, corn-on-a-sticks slathered in yellowish oil, kettle corn, and the endless treats spun from corn syrup.
Corn, more properly called maize, has become a very political creature in the food activist world, sucking up, as it does, endless tracts of fertile farmland and converting them to petrochemical-laced monocultures.
But it also has a more innocent and fundamental side, steeped in pre-history alongside wheat and rice as the three cereal grains that have kept humankind in its caloric frenzy.
There are five main kinds of corn, and a handful of others. Dent corn, so-named for the dent on top of the kernel, is softer and usually grown for animal feed and milled corn products, such as grits and corn meal. The flour corns, including blue corn, are easy to grind; sweet corn is the variety we eat.
But popcorn is the most playful corn, and possibly the source of all modern corn varieties, via the primal corn ancestor, a messy looking grass plant called teosinte . Popcorn is a special type of flint corn, so named for their hardness. All flint corn (also called Indian corn) has relatively large amounts of storage protein surrounding the granules of starch.
In a nutshell — or a kernel — the simple take on how popcorn pops is heat makes the moisture inside the kernel expand. But this belies the fascinating science beneath the hull, so to speak. And for this I turn to Harold McGee’s wonderful book, On Food and Cooking .
Some varieties of flint and dent corn will “pop”, but they expand far less than true popping varieties, which are generally smaller and contain more hard, translucent endosperm inside the hull (the endosperm is the fleshy white or yellow bit that makes up most of the kernel).
Popping varieties, and there are many — for instance, microwaveable popcorn is a different variety than movie popcorn — have another built-in feature that makes them pop better. Because the popcorn hull is denser, it conducts heat several times faster than the hulls of other corn. And because they are denser and thicker (ergo so annoying when you get them stuck in your gums), they can also withstand more steam pressure before they give way and the kernels explode.
So here’s the scoop on how that hard little kernel morphs from something you can break a tooth on into a puffy little snack. As the temperature inside the corn kernel passes the boiling point, the protein and the starch granules soften, and the moisture in the granules turns into steam. The steam then softens the starch even more, and thousands of little steam pockets exert a growing pressure against the hull.
When the pressure reaches about seven times the external pressure of the atmosphere, the hull finally bursts open and the soft protein/starch mixture puffs up and then stiffens as it cools — a mini-application of corn starch at its finest. It’s also one delicious enough to lure the average North American into eating 58 quarts of popcorn a year.
As far as flavour goes, the heating process also sets other chemical reactions in motion, one of them creating compounds that are shared by basmati rice.
McGee warns that if the popping is done in a tightly covered pot or pan with no way for the water vapour to escape, the endosperm will retain some of the moisture and be tough and chewy. Likewise if you leave a bag of kettle corn lying around and the humidity gets to it.
Conversely, if you don’t store your popcorn properly and it dries out, it won’t pop, not because it’s stale but rather that it no longer has a moisture content of 13-14 per cent.
As much as we movie- and fair-goers love our hot, fresh popcorn, it isn’t some kind of modern invention. It’s been found in archeological digs in Mexico dating back to pre-historic times. In fact, popping kernels in a fire may have been one of the earliest ways of cooking corn.
Much later, in the 19th century, Americans served popcorn as a breakfast cereal and made it into porridge, amongst other things. Now they were on to something. My favourite breakfast “treat” when I was a kid — and what a rare treat it was — was Sugar Pops, now simply called Corn Pops to assuage good parents’ fears of too much sugar so early in the day.
An overly cheerful prairie dog with peppermint stick six-shooters and too big a head lured kids in with his merry jingle: “Oh the Pops are sweeter and the taste is new. They're shot with sugar, through and through. Kellogg’s Sugar Corn Pops (pop, pop)… Sugar Pops are tops!" Get it… six shooters… POPcorn…?
Given corn is a good source of B-complex vitamins, including B 12 , and does contain some protein, it wouldn’t have taken much to convince me back then that Sugar Pops, or at least popcorn, qualified as one of the five main food groups.
But you wouldn’t want to overly depend on it in your diet. First of all the protein it contains is not complete (it lacks two essential amino acids). Plus corn-based diets in Africa and the Americas are often related to pellagra, which is caused by a niacin deficiency. (Sufferers are poorly nourished, weak and underweight and can even suffer dementia or death.)
Cows and the like do okay with getting the niacin out. However, we humans with our single stomachs do not.
But people have figured out strategies for getting around this. One method in countries such as Mexico and Guatemala is processing the corn in an alkaline solution (made variously from lime, ashes or burned mussel shells, as one Mayan group used to do) for tortillas and the like. This makes the niacin available to our human digestive systems.
Hominy, used in that delicious Mexican soup, pozole, is made from whole corn kernels, preferably white corn, that’s been cooked for 20-40 minutes in a solution of lime or lye, then the hulls and alkaline solution are washed off.
Corn Nuts, another North American favourite, are made from corn with the largest known kernels — Cuzco gigante, from Peru. They’re also treated with alkali then soaked in warm water for hours before being fried. And here you thought it was corn on steroids.
Like Sugar Pops, Cracker Jack also has roots reaching back to pioneering America, when early settlers made a treat by mixing popcorn with molasses. Corn dogs aren’t quite that historic — the first one rolled off the rack at a state fair in Minnesota in 1941.
As for corn-on-a-stick, it’s pretty easy to picture someone in a pre-Mayan world, jabbing a tiny cob, likely a popcorn cob, onto the end of a stick and roasting it over an open fire. The native Americans who first developed sweet corn would have approved — they thought its flavour was best when the corn was parched by the sun.
Glenda Bartosh is an award-winning freelance writer who
can’t stand a movie without popcorn.
