Nixtamalisation: the secret of the tortilla

Researcher: Santiago Lastra
Start date: 20 April 2015
End date: 25 June 2015


My goal was to find a formula for Nordic people to be able to use different local grains and seeds for making tortillas, opening another dimension of flavour and texture using this alkaline cooking process from Mexico.

The basic recipe for making nixtamalised corn involves cooking the kernels in a 1% calcium hydroxide (Ca(OH)2) solution at 80˚C for 1h, removing from the heat and steeping for 16–18h in the same solution, then rinsing and grinding/blending into the dough, or masa. The cooking and steeping times will vary according to the size and structure of the chosen seed/grain/legume, but the resulting flavour and texture will be unmistakably tortilla-like.

It was said thousands of years ago that the Indians of Mexico were made from corn. Appropriately then, the corn tortilla has been and is my home country’s staple food.

Traditional Mexican cuisine, as many other cuisines of the world, is based on survival, taking advantage of what is available in the environment in ways that make sense in the local geography and culture. Among the animals that are eaten in Mexico, for example, we tend to use all of its parts, even those less valued ones like heads, tongues, cheeks, eyes, ears, testicles, lips, tails, intestines. These ‘undervalued elements’, along with others like some wild plants and insects, are the essence of what the world knows as the taco.

The writer Jorge Ibargüengoitia is often attributed with imagining the creative process of the possible inventor of the taco:
“I want to invent something without plate, spoon, napkins and tablecloth, which is not necessary to wash and which carries the assurance that whatever is put in the mouth has never gone through another’s lips.”

The taco is a concept that, like the sandwich, pizza, sushi, and kebap, has become global. Yet, similar to these other foods, the general concept becoming available everywhere has led its particular forms to change. Many tacos made around the world use corn tortillas, but these tortillas are often made from low-quality industrial flour, frozen or dried or otherwise preserved to ship long distances, with the result of expensive, bad quality soulless Mexican food. A few people are making the extra effort to import good corn flour from different parts of Mexico, but this is difficult and not necessary realistic for everyone to do.

The funny part is that while the corn is the traditional ingredient for the tortilla, the technique might be more important to its identity. The ancient process of nixtamalisation is not only how we can make corn more nutritious and what allows us to turn it into a dough for tortillas, but also what gives them their distinctive flavour.

Forcing something like a corn tortilla taco, which evolved over a long period of time in specific geographic and cultural conditions, to work anywhere in the world is a difficult thing, and maybe not the way to make it taste its best. For example, cacahuanzitle, the particular type of corn used for tortillas, is common in Mexico but difficult to find other places, which has also led to using other, less suitable varieties for making tortillas storable and transportable as a global food. When it comes to flavour, we might be better off searching for other, locally appropriate ‘corns’ rather than forcing corn tortillas to exist everywhere but poorly.As we say in Mexico, “a fuerza ni los zapatos entran” – “not even the shoes enter by force”.

I chose to investigate the nixtamalisation process with the aim of finding a formula for people in the Nordic region – and other regions of the world – to be able to use different local grains and seeds for making their own fresh, tasty tortillas, and maybe less ‘authentic’ but more delicious versions of the taco concept.


‘Nixtamalisation’ comes from the Nahuatl words nixtli (ash) and tamalli (dough). Harold McGee describes how different societies used different alkaline substances: “The Mayas and Aztecs used ashes or lime; North American tribes, ashes and naturally occurring sodium carbonate deposits; and a contemporary Mayan group burns mussel shells for the same purpose.” (McGee, p.478)

One can imagine the process being discovered accidentally in steps. Perhaps weakly alkaline ash from a fire got into the pot where the corn was cooking and made it more digestible. The discovery of stronger alkalis like quicklime (calcium oxide, CaO) made from burning calcium carbonate (CaCO3) in limestone or seashells, and then that of calcium hydroxide (Ca(OH)2) by ‘slaking’ or mixing CaO with water, could have made the process more effective and consistent, yielding corn with the ability to be made into a healthy and fast-cooking dough.

CaCO3  CaO + CO2

CaO + H2O  Ca(OH)2

Here is a standard method, based on the traditional way: to nixtamalise corn, cook the kernels in a 1% calcium hydroxide solution at 80˚C for 1h, then remove from heat and steep for 16–18h in the same solution (Lopez, E.P. et al.).

After steeping, wash the corn a few times to remove excess calcium and the dissolved pericarp. Now the corn is ready to be ground by hand with a big stone hand blender called metate, which literally means ‘hand stone’. The water content of the dough should be around 55% (ibid.), so sometimes a bit of water is added during grinding. The resulting dough is called masa.

Let’s talk about the reactions happening during the process. In this case, it’s hard to describe it better than McGee already has:

“One of the major glue-like components of plant cells walls, hemicellulose, is especially soluble in alkaline conditions. Nixtamalisation softens the hull and partly detaches it from the rest of the kernel so that it can be rubbed off and washed away… and it releases much of their bound niacin so that we can absorb and benefit from it.” (p.478)

“During the steeping [in the alkaline solution after cooking], the alkalinity softens the hull and cell walls throughout, causes the storage proteins to bond to each other, and breaks apart some of the oil of the grains and emulsifiers (mono- and di-glycerides). After steeping, the soaking solution and softened hulls are washed away, and the kernels, including the germ, are then stone-ground to produce the dough-like material called masa. Stone-grinding cuts the kernels, mashes them, and kneads the mass, mixing together starch, protein, oils, emulsifiers, and cell wall materials, and the lime’s molecule-bridging calcium. With further kneading, this combination develops into a cohesive, plastic dough.” (p.481) In addition to the degradation of the pericarp, the partial gelatinisation of the starches in the kernels during cooking further facilitates the later formation of the elastic dough.

Other seeds

Based on this initial recipe (Lopez, E.P. et al.), I started to experiment with other types of seeds, grains and legumes, using different cooking and soak times according to the structural differences between them. Several tests yielded the following table of cooking time, soaking time and useful applications.

Table 1. Variations in cooking time and soaking time for nixtamalisation of different seeds, and possible applications.
Masa trials

The nixtamalised linseed became quite slimy and goopy

Tortilla trials

After this experiment with different types of seeds I realized compared to the non-nixtamalised controls that the calcium bath definitely helps to form a cohesive mass and give a certain tortilla flavour.

That distinctive tortilla smell

The characteristic aroma comes largely from the “alkaline processing [that] gives rise to [a] set of distinctive aroma molecules, including one that is a breakdown 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).” (McGee, p.479) This process can also yield “violet-like and spicy notes (from ionone and vinylguaiacol).” (ibid.)

Because the characteristic flavour and texture of corn tortillas are largely due to the nixtamalisation process, it is therefore possible to make high-quality tortillas rom grains of the Nordic region, or anywhere in the world.

We decided to put this hypothesis into practice, using the taco as a concept to connect the flavours and values of traditional taco culture on the streets in Mexico’s cities and towns with the raw materials and products of the Nordic region. On the surface it might look and taste different from what I’m used to in Mexico, but the sensation is the same. Wherever in the world it might be, a good taco is a good taco.

Pork cheek taco with nixtamalized Øland wheat tortilla and koji-chovy (10 portions)

Nixtamalised Øland wheat tortilla
Øland wheat is one of our favourite grains at the lab, and it was one of the most successful with the nixtamalisation process. It gives an aroma particularly similar to corn masa dough, with hints of nuts and caramelized roasted grain, a slightly chewy texture, a fine reddish brown colour with hints of yellow, and a surface resistant enough for any type of filling.
100g   whole Øland wheat grains
500g  water
5g     calcium hydroxide (we got ours here)
5g       salt
Mix the water with the calcium, add the wheat and cook in a pot for 45 minutes at medium heat. Remove from the stove and leave in the solution for 6 hours. Wash a few times until they are clean of calcium, strain and grind in a molcajete, the Mexican mortar and pestle of volcanic rock (or, if without, then blend in a food processor), until obtaining a smooth dough. Put the masa in a bowl and mix with salt. Weigh out balls of 10g and press between two sheets of parchment paper sprayed with oil. Cook the tortilla in a hot pan for 45 seconds on each side, and a final 45 seconds on the first side, until the tortilla is nice and cooked but not dry or brittle. Reserve in a damp towel.  dry and nixtamalised Øland wheat

dry and nixtamalised Øland wheat  nixtamalised Øland wheat blended into masa

nixtamalised Øland wheat blended into masa  rolling masa for tortillas

rolling masa for tortillas  pressing tortillas

pressing tortillas  cooking tortillas

cooking tortillas  folding the tortilla – ready to be filled

folding the tortilla – ready to be filled


Anaerobically lacto-fermented white cabbage. The acidity functions similarly to that of fresh lettuce dressed with lemon juice, but with added aromatic complexity and the cabbage’s mustard spiciness mellowed by the fermentation.
500g  winter cabbage
5g       seaweed powder
2%(w/w) salt
Slice the cabbage finely with a knife or mandolin. Mix the ingredients together and vacuum seal. Leave fermenting at room temperature for 3 weeks. Deflate and reseal the bag during the process if necessary, store in the fridge.

Koji-chovy cream

This element contributes the creamy, fatty, cheesy notes which are crucial to many tacos, as well as an underlying umami which helps to support the other flavours and round out the mouthfeel. In the process of working with our batch of koji-chovies begun in June 2014, we also realised that the aged orange-coloured fat provides a satisfying spicy accent, analogous to the chili in a traditional taco.
160g   cream
3g       koji-chovy passed through a sieve
1g        grasshopper garum
2         green juniper berries, finely choped
Reduce cream by half over low heat. Cool down cream, mix the ingredients and pour in a piping bag.

Pork cheek

On the streets is where we have always eaten tacos. It is a street food that has emerged with the need to do business and nourish people with parts of the animals that normally the rich people didn’t buy: offal, heads etc. The pork cheeks have a firm texture that falls apart in the mouth and a rich animal flavour that, when seared in the pan, unleashes all the wealth that anyone could want in the best of meats.
100g   pork cheeks
10g     olive oil
1          bay leaf
2         black peppercorns
3g       salt
Vacuum-seal the cheeks with the other ingredients. Cook for 12 hours at 72˚C. Sear in a very hot pan on both sides and slice before plating.


Herbs give freshness that balances the fatty and rich elements of the taco. In Mexico we normally use coriander and quelites, though as long as they are fresh and seasonal and clean the palate there are no rules for the specific flavour. In our tacos we have used wild pea shoots, bronze fennel, ramson flowers, cow parsley, and others, depending on what’s growing.

Cucumber vinegar

This quick spray of vinegar just before serving the dish reminds me of the fresh lemon aroma that you get in every taqueria with the lemon beside the plate. In this case it’s not for giving sourness, which is coming from the cabbage – instead it’s for giving an incredible refreshing impression to the eater. We made the vinegar using the active aeration method.


Heat the tortillas in a hot pan on both sides until they are soft again.
Sear the cheeks very fast with oil in a hot pan to give them a quick browning.
Plate the taco with a few dots of cream, some slices of cheek, a bit of sauerkraut and finish with the herbs and a spray of cucumber vinegar.

Sharing the taco

In June we had a couple opportunities to serve our taco to the wider public. One 12 June we were giving a presentation at Folkemødet, a festival for Danish political life, on the island of Bornholm, through our participation with other universities and civic organisations in the Smag for Livet project which focusses on taste education for kids and youth. We used the taco as a focal point to discuss different areas of the lab’s work, like the pursuit of umami, fermentation, foraging and wild plants, the exchange of cultures, and other techniques that give flavour like nixtamalization. I was glad to see that the participants liked it a lot, and the event described it on their website as a bite of heaven (Himmelsk!).

The following week, I joined Roberto at the University of Gastronomic Sciences in Pollenzo, Italy, where he was cooking for the students and faculty as part of their Tavole Accademiche program. On one of the days we presented the Øland taco but this time, we used tongue instead of cheek, representing the exchange of cultures between me and Roberto – a tongue-in-cheek multi-lingual play on the fact that the words for ‘language’ and ‘tongue’ are the same in both Spanish (lengua) and Italian (lingua) – along with herbs and flowers gathered from around Pollenzo. The cooks told me they were excited to try a real taco, which they hadn’t before, and the students told me that though they knew the concept, they had never appreciated it like that. I was happy to describe my project and how it developed in the lab, and afterwards when some students came to ask me the recipe, I was convinced that they would try to do it.


There is still much to explore about the nixtamalisation. But we can now say that using it to treat other grains not only allows us to create different types of masa and a certain particular tortilla taste, but also gives us the opportunity to exchange cultures, share techniques, and use the products we have in our environment to explore this old concept in new ways. Now that you know the secret of the tortilla, I invite you to try local grains and the products that you like to make delicious tacos, tostadas or even other preparations that you imagine will be delicious.


Roberto for the unconditional support he has given me since I started my project, giving me trust for making it big, and teaching me that things are not always what they seem.
Josh for his patience that has kept me going, because I am a little more crazy chef than a scientist, and above all for giving me the opportunity to be a part of this great team.
Jonas for the incredible bread, good sense of humour, his reviews and his always very interesting point of view.
Michael for making everything possible.
And the entire NFL team – everyone has had a very important part in my project: chemistry by Bernat; photographs by Rosemary, Charlotte and Afton; sauerkrauts by Rosemary.
And personally to my country to leave as a legacy to the world Nixtamalisation.

Santiago Lastra Rodriguez.


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López, O.P., Lara, F.G., Bello Pérez, L.A, 2008/9. La Nixtamalisación. Ciencias 92-93: Octubre 2008 – Marzo 2009. <>.

Lopez Nuñez, K.M., et al., 2015. Producción Industrial de Alimentos. <>.

McGee, H., 2004. On Food and Cooking: an encyclopedia of kitchen science, history and culture. Great Britain: Hodder and Stoughton, 2004.

Phillips, G.O., Williams, P.A., 2009. Handbook of hydrocolloids. Woodhead Publishing Limited, 2000.