Nixtamalization: The Ancient Process Behind Better Tortillas

Most people assume a tortilla is simply corn flour, water and a hot pan. It isn’t, and that assumption is exactly why so many tortillas taste and behave the way they do: dry, prone to cracking, faintly flat in flavour. The difference between those tortillas and a proper one usually comes down to a single step most producers skip entirely: nixtamalization.

Nixtamalization is the process of cooking and steeping corn in an alkaline solution, traditionally water and calcium hydroxide (known in Spanish as cal), before it is ground into masa. It sounds technical, and in a sense it is, but it is also one of the oldest food technologies in the Americas, developed long before anyone had a word for chemistry.

Where Nixtamalization Comes From

The practice originated in Mesoamerica, the cultural region stretching from central Mexico down through parts of Central America. Archaeological evidence suggests nixtamalization has been in use for several thousand years, with some of the earliest evidence for lime-treated corn found in what is now southern Mexico and Guatemala. It predates written history in the region and was already established practice by the time the Maya and later the Aztec built their civilisations around corn as a staple crop.

This wasn’t a refinement dreamed up for flavour. Nixtamalization solved a real nutritional problem. Corn on its own is a poor source of usable niacin (vitamin B3) and lacks the amino acid balance needed to make its protein nutritionally complete. Communities that adopted maize as a dietary staple without processing it this way, later on in Europe for instance, saw outbreaks of pellagra, a disease caused by niacin deficiency. Mesoamerican cultures, through generations of observation and practice, arrived at a process that unlocked the nutrients corn was withholding.

What Actually Happens to the Corn

The process itself is straightforward to describe, even if getting it right takes real skill. Dried corn kernels are cooked in water with calcium hydroxide, then left to steep for several hours. During this time the alkaline solution breaks down the pericarp, the tough outer skin of the kernel, which loosens and can then be rinsed away. The kernels are then rinsed and left as nixtamal, ready to be ground.

Beneath the surface, the alkalinity is doing far more interesting work. It breaks down the corn’s cell walls and converts bound niacin into a form the body can actually absorb. It also improves the balance of amino acids available from the corn’s protein, and increases the calcium content of the finished product substantially, since some of the calcium hydroxide is retained in the kernel itself.

Structurally, the process changes the starches and proteins in a way that gives the resulting dough, masa, its characteristic elasticity. This is the part most people never think about but chefs notice immediately. Untreated corn flour, ground straight from raw kernels, cannot form a cohesive dough in the same way. It lacks the pliability to be pressed thin and folded without cracking. Nixtamalized masa holds together, stretches slightly, and bakes into a tortilla with genuine structure rather than something closer to a cracker.

There’s flavour in it too. The alkaline cooking process develops a depth and slight earthiness in the corn that raw grinding simply doesn’t produce. Anyone who has tasted a tortilla made from fresh masa alongside one made from packet flour will notice the difference within a bite. For a fuller sense of the language behind terms like masa, milpa and stoneground, our glossary of useful words is a good place to start.

Why So Many Producers Skip It

Given all of this, it’s reasonable to ask why nixtamalization isn’t universal in tortilla production. The honest answer is time and cost. Cooking whole corn, steeping it, rinsing it and stonegrinding it fresh each day requires equipment, space and labour that most large-scale producers would rather avoid.

Instead, much of the tortilla industry relies on masa harina, a dehydrated, pre-nixtamalized corn flour that is rehydrated with water on site. Masa harina has its place and was a genuine innovation when it was developed in the mid-twentieth century, allowing nixtamalized corn to be shipped and stored without the need for daily processing. But dehydration and rehydration change the texture and flavour of the final dough. The elasticity is reduced, the flavour flattens, and the tortilla loses some of the qualities that made fresh nixtamal worth the effort in the first place.

For a business supplying restaurants at scale, masa harina is the more practical choice. For anyone trying to reproduce what a proper tortillería in Mexico actually makes, it’s a compromise.

How Masafina Approaches It

We don’t work with masa harina at Masafina. Every morning at our tortillería in North Acton, we nixtamalize whole heirloom corn from single-origin Mexican farms, cook it down with cal, steep it, rinse it and stoneground it using volcanic millstones brought over from Mexico. The corn we use comes from the same varieties that have grown in Mexican milpas, the traditional intercropped fields of corn, beans and squash, for generations, rather than the high-yield hybrid varieties bred primarily for industrial processing.

Andrea grew up around this process in Mexico City, watching relatives prepare nixtamal as a matter of daily routine rather than culinary theatre. When she and Laura built Masafina, keeping that process intact wasn’t a marketing decision. It was the only way to produce a tortilla that tasted like the ones Andrea grew up eating, with the pliability, aroma and depth of flavour that only fresh nixtamal delivers. You can see the full range of what comes out of that process, from tortillas to salsas and mole, on our products page.

Why the Process Still Matters

Nixtamalization isn’t a heritage flourish or a point of authenticity for its own sake. It is a functional, nutritionally significant process that fundamentally changes what corn is capable of becoming. Skip it, and you get flour. Do it properly, and you get masa, with all the flavour, nutrition and texture that generations of Mesoamerican cooks understood long before anyone could explain the chemistry behind it.

If you want to see the process in person, our tortillería in North Acton runs this same routine daily, nixtamalizing heirloom corn before it’s stoneground and pressed into tortillas that go out to kitchens across the UK.

Understanding nixtamalization changes how you think about a tortilla. It stops being a wrapper for other food and becomes what it always was in Mexico: a dish in its own right, built on a process with several thousand years of refinement behind it.