CornThe A”maiz”ing Grain

he popularity of corn cannot bedenied. As Dr. Paul Mangelsdorfsays in his book Corn: Its Origin,Evolution, and Improvement: “Itis the most efficient plant that wehave for capturing the energy of

the sun and converting it into food. True, weconsume directly only small amounts of corn:roasting ears, breakfast cereals, Indian pud-ding, and, for a somewhat different purpose, abeverage invented by a Kentucky minister ofthe Gospel, bourbon whiskey. But trans-formed, as three-fourths of it is, into meat,

milk, eggs, and other animal products, it isour basic food plant, as it was of the peoplewho preceded us into this hemisphere. Cornis as important today as it was for our nativepeoples.” Native American legend has it thatcorn is of divine origin—the food of the godsthat created the earth.

But as in many other instances, modernhumanity has managed to stir up controversywith this “perfect” gift. Today, genetically mod-ified corn, gasohol from corn, and even highfructose corn syrup have become sensitiveissues with people taking sides. Meanwhile,industry leaders call corn a future “manufac-turing plant”—pun intended; the list of corn-based products is constantly increasing.

The Spanish called it “maíz,” and thebotanical term became Zea mays. The Englishword was a bad choice, because “corn” refersto different grains in different places. Thename gaining popularity among scientiststoday is “maize.”

In less than a thousand years—cyber-speed by evolutionary standards—tiny “ears”of corn were growing all over Central Amer-ica. Long before Columbus or Cortez arrived,corn had become a major food crop acrossboth American continents. The explorers car-ried ears back home, and within another 100

years, corn spread as far as China. Now, cornis cultivated on six continents and is har-vested in more countries than any other single crop.

We need corn andcorn needs us

Corn has partnered with humans formore than 8000 years. Early Mesoamericanwall paintings tell of the food’s “discovery,” in the flatulence of a fox. In a commonMesoamerican myth, a fox follows an antinside a large mountain or boulder where thefox discovers a cache of maize. After eatingthe grain a vision of a wondrous new food was made evident in the haze of the fox’s flatulence!

There is a legend that old-timers tell of one

particular summer when it got so hot that the

corn in the fields startedpopping right off the

stalks. The cows and pigsthought it was a snowblizzard, and they lay

down and froze to death.

By Gail Haines

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Possibly, a more likelyscenario is that in ancientMexico, people practicedselective breeding on a grasscalled teosinte the old-fash-ioned way. By only using thebest/biggest/sweetest seeds,the ancestors of modern cornevolved over time. Peoplehave been modifying thegenetics of crop plants sincetime immemorial by this typeof selective breeding.

People needed maize tosurvive. Vegetarians, takenote! Combined with beansand squash—the way nativetribes prepared it—corn sup-plies all the amino acidsneeded for a healthy diet. Andcorn needs people, becausethe ears can’t reseed them-selves. Farmers must removethe kernels from the cobbefore they can be planted inthe ground, and the seedlingsmust be nurtured for them togrow.

Consider a typical fastfood meal: hamburger, fries, and a soft drink.The single food that links all these is … youguessed it, corn to feed the beef, corn syrupin the soft drink, the bun, and the ketchup,and corn oil to fry the potatoes. Every day, theaverage American eats around two pounds ofcorn in the form of dairy products and meatproduced from corn-fed cows, not countingroasted ears, muffins, cereal, chips, and the56 quarts of popcorn each of us consumeevery year. Much of it is grown in 12 contigu-ous Corn Belt states around Illinois.

Now for the biologyMaize is a cross-pollinating annual grass,

with a tall stalk, male tassels, and female ears.Seeds consist of an oily germ and anendosperm composed of starch and protein.The outer shell or hull of the seed is the peri-carp. Hundreds of different varieties still growin rural Central America, with kernel colorsranging from white to purple. But most culti-vated strains fall into five types (with the per-cent of commercial crops devoted):

1. Popcorn—the original cultivated corn.Moisture in the starchy core explodeswith heat into, arguably, the world’s old-est snack food (<1%)

2. Sweet corn—more sugar than starch.Add salt and butter (<1%)

3. Flour corn—soft. Makes great tortillas(12%)

4. Flint corn—hard. Grows in colderweather, used industrially and for live-stock feed (14%)

5. Dent corn, a flint/flour cross, accounts fora whopping 73% of commercial crops.The starchy interior feeds livestock andprovides raw materials for the chemicalindustry. In the United States, much of itis genetically engineered.A sixth type of corn called pod corn is

only used for research. Each kernel has itsown husk, so it is too labor intensive to usecommercially.

Genetically modifiedcorn—isn’t thatfrankenfood?

Who eats genetically modified or trans-genic (GM) corn? If you live in the UnitedStates, you do. Cows, pigs, chickens, anddogs do too. Some 70% of the processedfood on grocery store shelves contains geneti-cally modified corn and other plants in usesince the early 1990s. In the United States,GM foods are considered “nutritionally identi-cal” to the ordinary kind, so they are not nor-mally labeled.

How does genetically modified comparewith selective breeding? Well, selective breed-ing is really just a primitive form of genetictinkering. A farmer must choose a male and afemale plant, hoping that the gene responsiblefor a desired trait is transferred to their off-spring. The breeder can only guess, however,that the desired gene is present in the parentplants based on visual inspection; there is noguarantee that the offspring will indeed havethe desired traits. Success in selective breed-ing only comes after a long trial-and-errorprocess.

Genetic engineeringis a more targetedapproach, allowing thebreeder to take selectedgenes from one organ-ism and place them intoanother. The offspring inthis case is called agenetically modifiedorganism (GMO), or a transgenic organism.This is pretty straightforward and direct—plus, it allows something the selective breedercan never accomplish—genes from onespecies can be transferred to another, differ-ent species. Want grape-flavored corn? Not aproblem, but impossible with selective breed-ing. But seriously, although the process is notquite that simple, enhancing flavor, cropyields, and resistance to herbicides are desir-able traits that have already been engineeredinto GM corn. Genetic engineering has alsoallowed the incorporation of a gene that codesfor the Bacillus thuringiensis toxin, protectingcorn plants from insects.

Genetic modification may sound like biol-ogy, but chemistry makes it fly. DNA mole-cules get cut and pasted by chemicals calledrestriction enzymes, and “gene guns” shootgene-coated, microscopic particles of gold ortungsten directly into plant cells. Again, it isnot as simple as injecting a single gene intothe plant’s cells. A combination of genes frombacteria, viruses, andthe gene from thedonating organism isassembled. The bacter-ial and viral genes areused to break downbarriers between thetwo species beingcrossed, and they allowa mechanism for mak-ing sure the desiredgene is incorporated.As the genes areinjected into the plant’scells, it is suspectedthat the injection trig-gers a wound responsewhich helps its DNAintegrate the new gene.With the new genes onboard, one may engi-neer increases in thecorn’s productivity, orprotein concentrationor whatever is desired.

A qualitative test for GM corn. Hybrid cornsamples turn test solution dark blue, whilenormal kernels do not.

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Sounds great … whyisn’t everyone onboard?

Europeans are not fond of GM crops;only within the last two years have GM cropsbeen allowed in Europe, where each productmust display a special GM label. And in spiteof the United Nations official support, manydeveloping nations still are hesitant to con-sume GM crops, including corn. GM agricul-ture has had bad press around the world;some activists call it Frankenfood. Many peo-ple are not interested in eating unnatural food;corn is not supposed to taste like grapes!

Also, there are fears that unpredictableresults may occur when multiple copies of aforeign genetic code are injected into theplant. Critics of genetic engineering fear thatnew pathogens may be created within theplant, including bacteria that will be resistantto available antibacterial drugs.

Experimental attempts to coax corn intoproducing protein-based drugs and vaccinesinside the kernel are called “pharming.” Thisprocess is thought by some to be safer andcheaper than growing drugs in animal cell cul-tures. But in 2002, “pharm” corn that wasengineered to produce a pig vaccine slippedinto food fields by accident. In another case,some untested GM corn was processed intotaco shells before the mistake was caught; noone ate any of the shells and the foods weredestroyed. Still … corn pollen spreads far andwide, riding on the wind and farm machinery.Transgenic strains have been found fertilizingother varieties. Scientists are supposed to testevery new strain for possible allergens. Somepeople are worried that new “superweeds” orresistant insects will develop in response togenetic tinkering with nature.

You don’t want pig vaccine in your taco,and preserving genetic diversity is very impor-tant, but transgenic plants are already con-trolled far more rigorously than other foods.Fear of GM corn is costing lives in a fewAfrican countries that have refused Americanfood donations because they contain GMproducts, which Americans eat every day. Sci-entists try to stay ahead of the game, develop-ing corn strains that are sterile and evenstrains that grow underground, where nopollen can escape.

EthanolEthanol, the chemical name for ethyl

alcohol, CH3CH2OH, is in beer, whiskey, andwine and is one of the first chemicals peoplelearned to make. Corn whiskey was the origi-nal “White Lightning” of Prohibition days. Thelargest volume corn-based product on themarket today is fuel-grade ethanol—4 billiongallons of it is made each year. You alreadyburn some “gasohol” in your tank. All carsnow sold in the U.S. can handle a 15%ethanol, 85% gasoline fuel mix. “Flex-Cars”can burn at least 85% ethanol—E-85. The2007 Indianapolis 500 will run on 100%ethanol fuel made from corn—bringing newmeaning to “lightning fast!”

Ethanol burns cleaner than gasoline, producing little to none of the black, sootysmoke you see pouring out of an old car’sexhaust pipe.

CH3CH2OH + 3 O2 ! 2 CO2 + 3 H2O

Both ethanol and gasoline produce car-bon dioxide when burned, which becomesatmospheric “greenhouse gas” pollution. Butthere is a difference—corn captures CO2 fromthe air as it grows. Petroleum-based fuels, onthe other hand, release tons of CO2, whichhave been trapped underground for millionsof years.

You may have heard gasohol productionuses more energy than it provides. Critics

count every BTU of energy used to producethe gasohol, grow the corn, make the fertilizer,irrigate, and even build the farm machinery.Proponents use the newest technological datafor growth and production, and then they sub-tract coproducts made from corn protein andcorn oil and the energy value of sunshine. Acradle-to-grave analysis of the costs of pro-ducing ethanol would be a useful exercise,perhaps one that might be suggested by yourteacher. What we do know is that, thermody-namically, every energy conversion uses moreraw energy than it produces in fuel. The gainis convenience: coal to electricity, crude oil togasoline, corn to ethanol. Better technologyfavors the proponents, and ethanol already isreplacing gasoline-from-petroleum at an ever-increasing rate.

Oh, the sweet tasteof—corn?

Along with CO2 in your can of soda, thesweetener is almost certain to be pure corn.High fructose corn syrup (HFCS) is corn’smajor refined foodproduct.

Corn syrup,mostly glucose, is notvery sweet. Tablesugar (sucroseC12H22O11)—with eachmolecule composed ofone glucose and onesuper-sweet fruc-tose—has the taste welove. Food chemistsfound ways to get that taste from corn. Theyincreased the fructose level in corn syrup to42% (HFCS-42), 55% (HFCS-55) or 90%(HFCS-90), to make it as sweet as—orsweeter than—table sugar.

The 42% fructose syrup is produced byadding an enzyme that interconverts glucose

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and fructose; the 42% fructose/58% glucoserepresents the equilibrium ratio. The 90%fructose syrup is produced by a partial sepa-ration of the two sugars using a column thathas a high affinity for fructose. The 55% fruc-tose syrup is made from blending the 90%and the 42% and seems to be the standardsweetener for products such as soft drinks.

HFCS is cheaper than sucrose. It also pro-motes browning in bread, makes cookieschewy, prevents freezer burn, preserves cannedfruit texture, enhances flavors, and more. HFCSis in ketchup, hamburger buns, bacon, lunchmeat, whole wheat bread, and products youwould never suspect had sugar at all.

PopcornLong, long before there were movies

there was popcorn. Popcorn thought to be5,600 years old was found in a cave in centralNew Mexico. Today’s typical American eatsover 50 liters of popcorn each year. AndAmericans don’t just eat the stuff — they arethe world’s largest producers. Most of theworld gets its popcorn from the U.S. Midwest:Indiana, Iowa, and Nebraska.

A popcorn kernel is simply a seed withthree parts: the germ is the part that sproutsout of the seed during growth; the endospermis the starch that expands during the poppingprocess; and the pericarp, or outer hull, whichis made partly of cellulose. Now, not all cornhas the potential to pop. The maize must havethe right type of pericarp to produce the fluffyfood. The pericarp needs to keep moisturetrapped inside the corn kernel while it’s beingcooked. As the temperature of the kernelincreases, the pressure exerted by thegaseous H2O inside the kernel also increases.Once the internal pressure exceeds that out-side and the pericarp can no longer withstand

the force, the kernel splits open, turning thekernel inside out.

No one likes chomping down on un-popped kernels. The highest quality popcornhas a pericarp with a highly ordered crys-talline arrangement of its cellulose molecules.The two main reasons why kernels don’t popis they have insufficient moisture, or that thehull leaks. The ideal popcorn has about 14%moisture and must be stored in a tightlysealed container so it won’t dry out.

Eating popcorn is typically considered tobe a healthy act. It is fat-free, low in calories,and provides fiber. And it’s natural — accord-ing to the Popcorn Board (a nonprofit groupof popcorn processors), there is no geneti-cally modified popcorn currently available forsale in domestic or international markets.

Increased use ofHFCS = increasedsize of American?

Now HFCS is getting blamed for makingAmericans fat. Is this true? Or is it “Franken-fat”? Evidence shows today’s average Ameri-can is heavier than previous generations, andthe time frame of the weight increase—sincethe mid-1970s—matches the huge spike inHFCS use. But over the same 30 years,among other things, Americans have super-sized their diets, averaging 300 extra caloriesa day.

Chemically, HFCS-42 and HFCS-55 aresimilar to sucrose at 50–50%, but the bodyhandles extra glucose or fructose differently.Glucose is used directly by the body’s cells;fructose goes first to the liver. Glucose spikesa surge of insulin and also leptin, a hormonethat signals you have eaten enough. Fructosedoesn’t, so you may just keep eating! Fruc-

tose you don’t burn for energy and convertseasily into body fat.

Research is under way. Meanwhile, ifweight is a problem, avoiding those 32-ounce“super” drinks—sweetened with HFCS orsucrose—would be a no-brainer.

Solving controversy can superchargescience. Maize is already a great humanachievement—8000 years and still growing.Watch for further developments.

ChemMatters, DECEMBER 2006 7

In American Indian folk-lore, some tribes were

said to believe thatquiet, contented spiritslived inside of each pop-corn kernel. When their

houses were heated,the spirits would

become angrier andangrier, shaking the

kernels, and when theheat became unbear-able, they would burstout of their homes and

into the air in a disgrun-tled puff of steam.

REFERENCESMangelsdorf, P. Corn: Its Origin, Evolution,

and Improvement, Belknap Press,Cambridge, MA, 1974.

Tandjung, A., et al. Role of the pericarp cel-lulose matrix as a moisture barrier inmicrowavable popcorn.Biomacromolecules, 2005, 6, 1654–60.

Other information courtesy of Linda Stradleyand her web site, What’s CookingAmerica, athttp://whatscookingamerica.net.

Other references may be found in theTeacher’s Guide.

Gail Haines is a science writer and book authorfrom Olympia, WA. Her most recent article,“Honey: Bee Food Extraordinaire,” appeared in theDecember 2005 issue of ChemMatters.

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The ins and outs of popcorn.

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