Things related to corn: nixtamalization, planting techniques (the milpa), and journeys in North America

by Hari Balasubramanian

CorncobsThere are techniques of processing food that ancient cultures everywhere seem to have arrived at through an unstructured process of trial and error, and without a formal understanding of chemistry. This is how wheat grains turned into bread loaves, milk to cheese, soybeans to tofu, fruits to alcohol. As the techniques traveled in space and time, there were adaptations to the template, the creation of new variants. Much of what we call ‘cuisine' is precisely this ongoing process of collective experimentation.

This piece is about a millennia-old method of preparing corn which I discovered this year and which led me to other, unexpected links in history. In May I'd purchased a few pounds of corn grains. Not fresh corn on the cob that can be eaten grilled or steamed, but grains of corn that, like grains of wheat or barley or rice, have been kept dry for months after harvest. Naively I thought that cooking them should be easy: either soak them, like one soaks beans, and then, after they've softened a little, boil or pressure cook them. But the outer skin of each corn grain – the hull – was very tough. Even many hours of soaking and then cooking did not produce satisfactory results. While the cooked grains were softer, they still were somewhat difficult to chew. Something was clearly off.

I was missing an important step, a chemical process called nixtamalization. The word nixtamal comes from an indigenous Mexican language, Nahuatl. It refers to the process of cooking dried corn in an alkaline solution. This can be done easily at home. All you need is to boil corn, water and lime (not the citrus lime but the powder calcium hydroxide) together for fifteen minutes, then let it rest. After a few hours, the tough outer skin loosens, peels off easily on rinsing, leaving the kernels. The kernels can then be ground and made into a dough or masa. And it is masa that gives the remarkable aroma and taste to the freshly made tortillas, tacos, and tamales that Mexico and other Central American countries are famous for. If you mill whole corn grains without nixtamalizing them, then not only is the milling process harder because of the tough hull, but the resulting flour may not form into a dough. So much for the new fad of eating whole and unrefined grains!

But there's more to it than convenience and taste. Nixtamalization may have evolved for a specific reason. Niacin, a source of Vitamin B3, which remains trapped and inaccessible if the corn is not nixtamalized, becomes more available if it is. This vital fact, however, remained unknown for a long time. As we'll see, cultures around the world that took up a diet high in corn but without nixtamalization paid a heavy price.


Until my mid twenties, I used to think that the crops and vegetables that I knew had always been available in all parts of the world, in the same way that that air and water are everywhere. I also believed that agriculture had been humanity's primordial condition. Only after reading books like The Columbian Exchange and Guns Germs and Steel – what a thrill it was to be reoriented to this new way of looking at the world! – did I realize that each grain has a specific place of origin; that the organized cultivation of grains is relatively recent; and that the surpluses stored after harvest – the nutritional energy tightly locked in dried grains can be used months or years later – changes the structure of society itself.

Maize, known in the United States as corn (I'll use maize and corn interchangeably from here on), was cultivated about nine or ten thousand years ago, somewhere in south-central Mexico, from a wild ancestor called teosinte. Advances in the farming of maize fueled the great empires of Mexico and Central America: the Olmecs, the Mayans, the Aztecs. The organized societies that emerged in this part of the world before Spanish arrival are referred to as the Mesoamerican cultures. The Mesoamerican cultures discovered the alkaline process to treat corn – what came later to be called nixtamalization – using naturally occurring sources of slaked lime (calcium hydroxide) and ash (potassium hydroxide). How and where this happened is hard to trace, but the earliest archaeological evidence dates to 1200-1500 BC in coastal Guatemala [1].

After Columbus' arrival in 1492 inadvertently connected the long isolated Western and Eastern hemispheres, corn jumped the oceans and reached other continents. Along with wheat, rice and potatoes, it became one of the star crops of the world, with relatively high yields per acre. From Africa to Europe to China, maize farming became popular among the poor. But knowledge of nixtamalization does not appear to have traveled with the crop, though the Spanish were certainly aware of it. Nixtamalization was ignored probably because it was not considered of any value. This meant that there were populations around the world with diets that relied heavily on unprocessed corn.

A terrible disease called pellagra affected some of these populations. Pellagra resulted in a range of symptoms, from the visible degradation of skin (image of a patient), to diarrhea, to dementia. It was common in Northern Italy where the peasant population consumed polenta, a porridge made of corn flour, on a regular basis. In the early 20th century, the disease took on epidemic proportions in the southern United States, affecting millions of people. There too it affected people on the lower end of socioeconomic status, those who ate corn regularly and did not have the luxury of a varied diet. While pellagra was clearly linked to the consumption of corn, the precise details of this epidemiological mystery took were not unraveled until the 1930s. By this time the disease had consumed innumerable lives all around the world, 100,000 in the southern United States alone [2].

In the late 1930s, the reason became clear. Pellagra was due to a lack of niacin, which is linked to Vitamin B3. Corn happens to be relatively deficient in niacin, and without the chemical changes that nixtamalization brings about, what niacin that exists in the grain cannot be released. A diet heavily reliant on unnixtamalized corn without other food sources that could compensate for the niacin shortage can therefore cause pellagra. This simple but invaluable discovery lead to two equally simple solutions: either eat a varied diet that covers all nutritional needs; or, if corn remains a major part of the diet since the economic means for a varied diet aren't there, then have it nixtamalized. The incidence of pellagra dropped dramatically from the 1940s onwards.

It's fair, then, to hypothesize that in the millennia before Europeans arrived, pellagra outbreaks were common in Mesoamerica too, where corn was a staple – until the discovery of nixtamalization solved the problem.


IMG_20160105_122209_748There is also another interesting way in which niacin deficiency appears to have been addressed by the Mesoamerican cultures. In modern agriculture, we are used to acres of land dedicated to a single crop. The Midwestern states are famous for large scale mechanized agriculture: tracts of land dedicated to growing row upon row of corn. But in Mesoamerica, maize was not cultivated in isolation. It was one crop among many – beans, squash, avocadoes – that were simultaneously grown in a field called milpa. From Charles Mann's 1491:

"Milpa crops are nutritionally and environmentally complimentary. Maize lacks digestible niacin, the amino acids lysine and tryptophan, necessary to make proteins and diets with too much maize can lead to protein deficiency and pellagra, a disease caused by lack of niacin. Beans have both lysine and tryptophan, but not the amino acids cysteine and methionine, which are provided by maize. As a result, beans and maize make a nutritionally complete meal. Squashes, for their part, provide an array of vitamins; avocadoes fats."

Milpa has other effects too. While maize takes out nitrogen from the soil, the beans make it available, thus ensuring that the soil is not too depleted and can be used for future cultivation. Maize, which is grown first, provides the shoots which the vines of bean use as support to ascend. Meanwhile, the low-growing squash reduces the possibility of weeds gaining sunlight, and by covering the ground it keeps the soil from becoming dry. Thus the three as a team achieve what each crop individually might not have been able to on its own.

Like nixtamalization, milpa appears to have emerged through a slow process of collective experimentation, without a centralized or coordinated effort. Maize, squash and beans were each domesticated at different moments in time, and for them to come together into the same field took at least a few thousand years. But once the basic templates of milpa and nixtamalization had been perfected, they proved to be powerful. Radiating outwards from Mexico, they eventually influenced food and cultivation practices in the distant corners of North America. I'll turn to this next.

The Massachusetts Connection

From Oaxaca in southern Mexico, one of the centers of maize and milpa cultivation, to Amherst in western Massachusetts, where I now live, it's a distance of about 3000 miles by land. Today, Massachusetts isn't considered corn country. Except for the sweet corn stalls in rural parts or corn grown as feed for cattle, there's not the deep knowledge of or reverence for corn that exists in Oaxaca. When I looked around supermarkets and grocery stores in Amherst, I could not find slaked lime, calcium hydroxide, that I needed to nixtamalize the dried corn grains I'd purchased. No one knew what I was talking about; I had to order it online. Which makes sense: in Massachusetts, you are more likely to find artisanal bakeries, discussions about yeast and what to do with wheat and rye flour, than tortillerias and how to make masa. In other words, it's a culture largely based on adaptations to the European template rather than the indigenous North American one.

But it need not have been this way. Let's go back, for a moment, to November 1620. The group of 102 colonists that would later be called the Pilgrims have just arrived, after an arduous journey in a cramped ship called the Mayflower. After a terrible winter of sickness, only 47 of the them are alive. In March 1621, they are approached by Massasoit, the Wampanoag chief. The Wampanoag are one of the numerous Algonquin speaking people of New England. For his own reasons, Massasoit makes the decision to ally with the Pilgrims. An intermediary, Tisquantum, known by the popular name Squanto, helps the Pilgrims. Among other things, he teaches them indigenous methods of farming. The settlers gain a foothold, paving the way for the European settlement of the American Northeast.

So what exactly are the indigenous methods of farming that Tisquantum taught? Planting corn, beans and squash in the same field, exactly the idea of a milpa! So here we have a native of coastal Massachusetts who knew how to cultivate an agricultural package that was first perfected in faraway Mexico. I find this detail remarkable: it tells us how the knowledge of agriculture can transmit itself across long distances, moving from one network to the next in a relay. It tells us also how interconnected trade networks must have been in North America before European arrival.

Cahokia-illustrationThrough a slow process of dispersion – crops have to be adapted to changes in weather and seasons as they move north – corn, squash and beans made it from Mexico to Hohokam and Pueblo cultures the southwestern United States; to the American south, where it led to a flowering of the Mississippian chiefdoms and the 12th century urban center Cahokia near modern day St. Louis (right image presents an artist's recreation); to coastal Virginia, where the Jamestown settlers in 1607 encountered the expanding agricultural societies of the Tsenacomoco; and finally, a few hundred years prior to the arrival of the Pilgrims, to New England.

Contrast the hot and dry and mountain valleys of Oaxaca with the brutal winters, snows, the variations in the length of the day, the limited spring and summer growing seasons of Massachusetts, and we get a sense of the long journey that the Mesoamerican crops made. Equally striking is the fact that along with corn, the knowledge of nixtamalization traveled too. Among the dozens of North American indigenous cultures, including the Algonquin Northeast, corn was consumed after some form of alkaline treatment using naturally occurring substances such as hardwood ash and lye [3].

Thus, while the the Massachusetts that I live in today seems not so steeped in milpa and nixtamalization, it certainly was prior to European settlement. Fields of corn, squash and beans surrounded every home and towns sprawled along the major rivers of Massachusetts. While this Algonquin agricultural past – a use of the land different from the European style: fire was used creatively to burn selected portions of the landscape – is not mainstream anymore, traces of it have persisted. In the early 20th century, an ancient corn field that dated back at least to 1654 was discovered fifteen minutes from where I live, close to the meandering path of the Connecticut River [4]. And the descendants of the Wampanoag in Chilmark, Massachusetts, still teach old methods of planting corn, squash and beans to their children in grades 3-6.

Had the trajectory of American Indian development in the northeast not been interrupted by a deluge of European immigrants and wars after the arrival of the Pilgrims, had there been an intermingling of the cultures rather than a displacement of one by the other, perhaps indigenous perspectives might have been more mainstream in Massachusetts.


As it happens, nixtamalized corn is now returning to the United States. If at one time Mesoamerica exported its ideas of cultivation north, today people from that part of the world themselves have immigrated north in large numbers, bringing their culinary practices with them. An interesting fact, though of no practical relevance, is that the mixed race (mestizo) and indigenous immigrants of Mexico and Central America, who have changed the demographic in many American states, also happen to be the closest genetic relatives of the North American Indians.

20170716_131644Even in rural western Massachusetts, there's a Mexican family that sells corn tortillas made from scratch. And walking distance from my apartment, there's a Salvadorian restaurant called El Comalito. My favorite dish there is the pupusa, which unlike the tortilla, is thicker and is stuffed with mashed beans and cheese. At El Comalito, the pupusas always take longer than other dishes – you can hear the dough getting patted in the kitchen soon after the order has been placed, then placed on the hot griddle. Once the dish arrives, there's that unmistakable aroma and taste that I'd always enjoyed and which – thanks to my own attempt at cooking corn – I now recognize can come only from nixtamalization.

What long and complicated histories are hidden in the things we eat!



1. Staller, John E.; Carrasco, Michael (2009). Pre-Columbian Foodways: Interdisciplinary Approaches to Food, Culture, and Markets in Ancient Mesoamerica. Berlin: Springer-Verlag. p. 317.

2. Bollet, Alfred Jay. "Politics and pellagra: the epidemic of pellagra in the US in the early twentieth century." The Yale journal of biology and medicine 65.3 (1992): 211.

3. Briggs, Rachel V. "The Hominy Foodway of the Historic Native Eastern Woodlands." Native South 8.1 (2015): 112-146. Also check out Rachel Briggs' excellent website: All Things Hominy.

4. Delabarre, Edmund B., and Harris H. Wilder. "INDIAN CORN‐HILLS IN MASSACHUSETTS." American Anthropologist 22.3 (1920): 203-225.

5. Image credits: The first image is from here; the second is a picture of a milpa that I took at the Ethnobotanic museum in Oaxaca City; the third is an artistic rendition of Cahokia from here; and the last is a picture of pupusas that I took at El Comalito.