Now reading All Nixt Up

All Nixt Up

Behind nixtamalization, the process that turns corn into masa.

This story comes from Lucky Peach #10: The Street Food Issue. For more great stuff like this, subscribe to the magazine!

Readers of Lucky Peach Issue One may remember how the alkaline salt kansui, or sodium carbonate, makes ramen noodles sturdy, chewy, and exceptionally delicious. Subjecting dried corn to an alkaline treatment is similarly transformative. The process of steeping corn in an alkaline solution, called nixtamalization, was developed by ancient Mesoamericans and is employed today in the creation of every single tortilla, tamale, gordita, and huarache, whether from a factory or a grandmother’s hand press. And it’s culinary genius.

Nixtamalization, from the Aztec word nixtamalli (a combination of the words for ashes and dough), benefits those who work with and consume corn in four significant ways.


1. Grinding

As early as 1500 BC, pre-Columbian civilizations across what would become Central America, Mexico, and the American Southwest—Incas, Mayas, Aztecs, and others—soaked dried corn kernels in water mixed with ashes and lime to break them down and make them more easily digestible and nutritious. Some cultures used lime (calcium hydroxide, or “cal”), which was made by burning limestone, while others used potassium carbonate, also called potash—the result of charring marine shells to ashes. Both substances have the effect of raising the pH of the water from neutral to alkaline.

Cooking and soaking corn in an alkaline solution partially dissolves the cell walls of the kernels, separating the pericarp, or hull, from the kernel and making it easier to grind the corn for consumption.

In an era when a fancy home blender can liquefy a cell phone, it’s hard to grasp the importance of this transformation. But Dave Arnold, the owner of culinary lab and cocktail bar Booker and Dax in Manhattan (and a guy who nerds out about cooking techniques for a living), has spent a great deal of time researching and experimenting with nixtamalization. He notes that Europeans placed just as much focus on grain grinding, and, in fact, had wind- and water-powered grain mills well before the native populations of the Americas.

“Grinding of grains in early agriculture, up until the Industrial Revolution, was extremely important in how labor is divided. If you have to spend hours grinding corn”—in your kitchen, every day—”it’s kind of a big deal.” Hence, the importance of making corn easier to process.

2. Pliability

The alkalizing process also links the corn’s proteins to one another, turns some of its oil into emulsifiers, and gelatinizes a portion of the starch. In normal-people language, that means it can be made into a soft dough called masa. Masa can then be made into all manner of wonderful foodstuffs, including tamales, tortillas, and all their permutations: chips, arepas, gorditas, and more. Any corn product that needs to stick together and be pliable has been nixtamalized or “wet-milled.” Un-nixtamalized, or dry-milled, corn products include grits (though those were once nixtamalized), polenta, cereal, beer, and anything made from cornmeal or corn flour, like cornbread and corn muffins. (The hominy used to make pozole and corn nuts is also nixtamalized, though it’s not ground into masa.)

3. Nutrition

Niacin (vitamin B3) is an essential organic compound. If you eat a varied diet with enough chicken, beef, fish, whole grains, leafy greens, nuts, legumes, tofu, fruits, and/or dairy, you’re good on niacin. Eat a diet founded on un-nixtamalized corn, like the poor people of Europe or the southern U.S. in the mid-eighteenth through the mid-twentieth centuries, and you will learn some hard truths about pellagra.


Pellagra is a gruesome and ultimately deadly disease with symptoms that include diarrhea, dementia, hair loss, confusion, swelling, and grotesque lesions. The disease was first documented in Spain in the mid-eighteenth century. It ran rampant throughout Europe for a couple hundred years, and arrived in the United States around the first quarter of the twentieth century. Observers quickly pointed to corn consumption as the cause—a gentleman named Théophile Roussel even led a campaign to remove corn as a staple of the French diet in the 1800s, and mostly eradicated the disease there—but it wasn’t until the severe outbreaks in orphanages, mental institutions, and prisons in the American South that scientists finally figured out exactly the cause: niacin deficiency.

The Mesoamericans, who had been eating corn as a staple for a thousand-plus years, didn’t experience the same prevalence of pellagra. Their nixtamalization process unleashed the bound niacin in corn, making it absorbable through human digestion, while also adding dietary calcium, improving the accessibility of six amino acids, and reducing poisonous substances produced by fungi called mycotoxins. In a case of cosmic irony, when the Europeans, with their powerful grain mills, imported corn cultivation from the New World, they didn’t bother bringing the corn-treatment process.

4. Flavor and Aroma

To Arnold, a constant tinkerer, the previous three benefits of nixtamalization are interesting intellectually. But the most compelling byproduct of the process, the one that makes it a topic worthy of study and passion, is the flavor and aroma it yields.

Anyone who has walked the streets of Mexico City, or been inside a restaurant that makes its own masa, or inhaled deeply while opening a bag of fresh tortillas knows the heady and subtly funky, intensely corn-y smell. Harold McGee, food scientist emeritus, breaks it down thusly in his essential tome On Food and Cooking:

“Alkaline processing gives rise to yet another set of distinctive aroma molecules, including one that is a breakdown of a product of the amino acid tryptophan, and a close chemical and aromatic relative of a characteristic note in concord grapes and wood strawberries (aminoacetophenone, related to the fruits’ methyl anthranilate). Masa can also have violet-like and spicy notes (from ionone and vinylguiacol).”

Arnold writes on his site, Cooking Issues, that cooking corn with cal “saponifies (the process by which fats are turned into soap) some of the fat in the corn germ,” adding to the distinctive taste and texture.

visited a traditional molino, or corn mill, and a tortilleria on a recent trip to Mexico City.

The Aranda molino, a small open garage in a dirt alley, among rows of raw-chicken vendors near the San Juan Market, has been around for more than a hundred years. It’s a bare-bones operation. A stockroom in the back of the space holds the cal and the corn—about seven tons at the time of my visit. The main room has a counter with a telephone and a scale on one side—that’s where business is done—and, on the other, vats for steeping and rinsing the corn, a cylinder for heating up the water, and an ancient-looking molino, or milling machine, that churns out masa. There is a larger, shinier, more modern mill that is currently being used as a sort of storage rack. “The automatic is a lot more efficient,” says miller Frederico Antonio Carrera, gesturing to the newer mill. “But my father never wanted to do it the modern way.” More important, he can fix the manual machine himself when it breaks, without having to call a mechanic.

To make masa, Carrera takes about a ton of dried white Mexican field corn at a time, adds cal (his brand of choice is called Nixtacal), and covers the combo in near-boiling water, at ninety degrees Celsius. The mixture steeps all day, covered by a tarp. Every hour, he stirs the corn with a large prehistoric-looking paddle, to circulate the corn through the solution. After a day of steeping, he rinses the corn in cold water in a new vat, removing the cal and the corn kernels’ seed coats. If he wants white-corn tortillas, the corn will go straight to the mill. For yellow, he doses up the cal after the rinse.

Carrera couldn’t explain the chemical process behind why adding more cal at this stage made the tortillas yellow—he said it was just an aesthetic thing, but that added cal does change the flavor. (My perception was that it was deeper and more bitter.)

The large molino contains two giant volcanic rocks, one with hand-carved indentations (“teeth”), which Carrera sharpens with a chisel whenever they get dull. Carrera feeds the corn into the mill by hand, slowly grinding the kernels into masa, which will be sold warm to tortillerias, restaurants, street vendors, and—as evidenced by the little old lady who stopped by during my visit to pick up a pound—locals cooking at home.

Next door at tortilleria La Caprichosa (“The Whimsical”), Raymondo Herrera takes on the dangerous and fast-paced task of running the tortilla press. His coworker, who lost the tip of his finger to the crushing volcanic stone rollers of the machine, mans the cash register. Standing to the left of the machine, Herrera works his masa through the rollers, watching for the right consistency and adjusting the grind and water content, then shepherds the soft but not too sticky dough through a second set of rollers that feed into a cutter. The tortillas barrel out onto a conveyor belt where, if they are not tossed for being imperfect—torn, too sticky—they’re cooked on one side, flipped onto a lower belt, cooked on the other side, flipped onto a cooling belt, then fed out the end. A female relative waits by the end chute, collecting the warm, cooked tortillas that barrel out of the machine, and packaging them for customers—to the tune of about eleven thousand tortillas a day.

Compared to the chill vibe of the molino, where a majority of the job involves watching corn steep, the tortilleria is a wild, noisy place, dominated by the churning of the rickety tortilla machine.

Eating tortillas made from hours-old masa at a tortilleria in Mexico City is the Platonic ideal of tortilla consumption. Achieving that freshness and flavor at a home or restaurant level is a fairly difficult proposition. Masa is temperamental. Alex Stupak, chef and owner of Empellón and Empellón Cocina in New York, says, “Masa is an artisanal, inconsistent thing. It’s a little different every day depending on if it’s raining out or dry. It’s also volatile. Ideally, it should never be refrigerated. Refrigeration affects the aroma and texture in an adverse way. But the kicker is that if you don’t refrigerate it, it will take on an orange hue and go rancid in a few hours.” He hopes his restaurants will one day demand the supply to justify the construction of a dedicated tortilleria the way certain French restaurants have their own boulangeries. Until then, he’s content to buy masa.

Many chefs in the U.S., Mexico, and elsewhere will either buy masa from a mill (and hand-press their tortillas) or buy tortillas made fresh from a tortilleria. Cities like Chicago and LA are lousy with fresh masa producers. Tortilleria Nixtamal, a well-known source for fresh masa and tortillas in New York City, sells about two hundred pounds of tortillas every day.

Danny Bowien, who opened his Lower East Side restaurant Mission Cantina in November, decided not to outsource. Says Bowien, “It’s hard, it’s really hard. You can make it, but it’s not going to be as good as the best tortillas you have in Mexico City—the same way old Italian grandmothers can make the sickest pasta like it’s nothing to them.” Sue Torres, who makes masa in-house and employs a full-time tortilla-maker at her Manhattan restaurant, Sueños, shares the sentiment: “The first time I tried to make a tortilla by hand in Mexico it was an utter and complete disaster. And some of these women don’t even use a tortilla press. It’s about the consistency. It’s about how it feels in your hand. If it has too much moisture, it’s going to stick to your hands. If it’s too dry, you can’t knead the dough. You can’t leave the dough alone, and the dough has to be warm. There’s an art to making it.”

Bowien’s setup in the corner of his open kitchen at Mission Cantina is about one-fifth the size of the molino and tortilla press I observed in Mexico City. It took him weeks to get the masa to a place where he felt comfortable serving it, and his machinery broke three times in the first month. “We got the volcanic rocks. And those are broken,” he says. “We didn’t know how to properly sharpen them until the other day. And we didn’t know we had to sharpen them. We thought they were just rocks that rub together. The way we’re making it is probably way wrong, but we’re happy with the way it’s coming out.”

On the other end of the difficulty spectrum are restaurants making tortillas made from masa harina, familiarly known by the misnomer Maseca (Mexico’s most famous brand of the stuff). To make masa harina, factories nixtamalize corn on a massive scale, make masa, flash-dry it, and pulverize it. McGee writes that because it’s made with less water than normal masa and then dried, “masa harina has less masa aroma and an added browned, toasty aroma, and produces a softer texture than fresh masa.” Compared to fresh masa, which, when refrigerated, stays fresh for a day at most, masa harina holds the promise of fresh tortillas whenever the mood dictates. Just add water, knead, and go. Torres admits it works on the fly but says it’s “the equivalent of giving an Irish man boxed potatoes.”

Today, using Maseca is the most common way of making “fresh” tortillas. Just don’t serve them to Dave Arnold. “The flavor of a freshly done one is just so far superior,” he says of tortillas made from fresh masa. “It’s kind of a pain in the ass, but no one in a good restaurant would use stock that they bought from somebody else. I think there was a fundamental lack of respect for Mexican cuisine and most Mesoamerican cuisines until fairly recently. People just haven’t seen it as something that’s worth thinking about in a very hardcore way, and I think that’s really sad. I think it’s a cuisine that’s worthy of great respect. So I think it’s going to change.”

Of course, as with any complex cooking technique, certain experimental and avant-garde chefs hope to push nixtamalization to the next level. Both Arnold and Noma chef René Redzepi have played around with nixtamalizing rye. Stupak has experimented with a number of heirloom grains, most recently buckwheat groats. When I was in Mexico I visited chef Enrique Olvera’s Pujol, a restaurant focused on applying sophisticated cooking techniques to traditional Mexican ingredients, and ate both nixtamalized papaya and nixtamalized chilacayote (green squash). They were good. But not as good as his tortillas.