What Nixtamalisation Is and Why It Matters for Your Tortillas

The process that created a civilisation

Nixtamalisation is not just a cooking technique - it is the process that made Mesoamerican civilisation possible. Without nixtamalisation, corn would be a nutritionally incomplete food. With it, it becomes a superfood capable of sustaining empires.

The process is deceptively simple: cook dried corn in water with lime (calcium hydroxide), let it rest, wash it and grind it to obtain masa. But what happens at the molecular level is extraordinary: the lime breaks down the cell walls of the grain, releases the niacin (vitamin B3) that would otherwise be inaccessible to the human body, increases the calcium content and transforms the corn's proteins, making them more digestible.

The European peoples who adopted corn after the conquest but did not adopt nixtamalisation suffered epidemics of pellagra - a disease caused by niacin deficiency. The Mesoamericans, who had been nixtamalising for thousands of years, never had this problem. It is one of the clearest examples of ancestral wisdom validated by modern science.

The history of nixtamalisation

The oldest evidence of nixtamalisation dates to 1500 BC in Guatemala, although it was probably practised much earlier. The word comes from the Nahuatl: nextli (lime ashes) and tamalli (cooked corn masa). The Aztecs called the process "nextamal".

Each Mesoamerican culture developed its version: the Maya used ash from sea shells, the Olmecs wood ash. The principle was the same - an alkaline solution that transforms the corn. Today, quicklime or slaked lime (calcium hydroxide) are the most used.

The science behind the process

What exactly does the lime do to the corn? Several fundamental changes:

• Releases niacin: The vitamin B3 in corn is chemically locked (niacytin). The lime breaks these bonds, making the niacin bioavailable.
• Gelatinises the starch: The lime partially cooks the corn starch, creating a masa that can be formed and held together - without this, there would be no tortillas.
• Removes the pericarp: The hard skin of the grain softens and comes off during washing, improving the texture.
• Changes the amino acid profile: The corn's proteins become more similar to those of whole grains.
• Adds calcium: Nixtamalised masa contains significantly more calcium than untreated corn.
• Develops the aroma: The characteristic smell of freshly made tortillas - that sweet, earthy, unmistakable aroma - is a product of nixtamalisation.

Home nixtamalisation step by step

You can nixtamalise at home in Spain. It is easier than it seems. You need:

Ingredients

• 500g dried corn for nixtamal: Look for cacahuacintle corn or dried white corn in Mexican shops. Popping corn does NOT work. Some Spanish farmers grow old corn varieties that also work.
• 1.5 litres of water
• 10 to 15g of lime (calcium hydroxide): Bought at hardware shops as "slaked lime" or "builders' lime". Make sure it is pure calcium hydroxide, with no additives. It is also sold online as "lime for tortillas" or "lime for nixtamal" in Mexican shops.

Process

Step 1 - Dissolve the lime: In a large stainless-steel pot (never aluminium), dissolve the lime in the cold water. Stir well until there are no lumps.

Step 2 - Add the corn: Rinse the corn kernels and add them to the lime water. The kernels should be covered by at least 5cm of water.

Step 3 - Cook: Bring to the boil over medium-high heat, then reduce to medium-low. Cook for 30 to 45 minutes. The exact time depends on the type of corn and its hardness. The kernels are ready when, rubbing one between your fingers, the skin comes off easily.

Step 4 - Rest: Turn off the heat and leave the kernels in the lime water for 8 to 12 hours (overnight). This rest is crucial - during these hours, the lime continues to penetrate the grain and transform its structure.

Step 5 - Wash (nejayote): The next day, drain and wash the kernels under running water, rubbing them between your hands to remove the skin (pericarp) and the excess lime. The washing water is called nejayote and is traditionally used to cook beans or as a fertiliser.

Step 6 - Grind: Here is the challenge at home. Traditionally a metate (volcanic stone) is used. At home you can use a manual corn mill (corona) that costs €20 to €30 in Latin American shops, or a powerful food processor. The texture should be a soft, moist masa that does not stick to the hands.

"A tortilla made with fresh nixtamalised masa is a completely different food from a tortilla made with Maseca. Not better or worse - different. It is like comparing sourdough bread with sliced bread."

From masa to tortilla

Once you have the nixtamalised masa, making tortillas is a matter of practice:

• Form balls of masa the size of a large walnut (40 to 45g for taquero tortillas).
• Flatten in a tortilla press (or between two plastic sheets with a heavy plate).
• Cook on a very hot comal or cast-iron pan, without oil.
• 30 to 45 seconds per side. The tortilla should puff up slightly on the second turn - that indicates the masa is well nixtamalised.

Maseca vs fresh nixtamalised masa

Maseca (nixtamalised corn flour) is corn that has already been nixtamalised, dried and ground into powder. It is extremely practical and produces decent tortillas. But there are important differences:

• Flavour: Fresh masa has a more complex, sweeter, deeper aroma.
• Texture: Tortillas from fresh masa are more flexible and have a more rustic, less uniform texture.
• Nutrition: The industrial drying process loses some nutrients that fresh masa retains.
• Practicality: Maseca wins here. It is prepared in 5 minutes; home nixtamalisation takes 12+ hours.

Both options are valid. For day to day, Maseca is perfectly acceptable and is found in many Mexican shops in Spain. For special occasions or when you want the full experience, home nixtamalisation elevates any tortilla recipe to another level.

Beyond tortillas

Nixtamalised masa is not only for tortillas. With it you make:

• Tamales: The masa is beaten with lard until fluffy.
• Gorditas: Thick tortillas filled with chicharrón, beans or cheese.
• Sopes: Masa bases with pinched edges to hold stews.
• Tlacoyos: Ovals of masa filled with bean, broad bean or requesón.
• Atole: A hot drink of masa dissolved with cinnamon and sugar.
• Pozole: The whole nixtamalised kernels (unground) are the base of pozole.

Mastering nixtamalisation is mastering the foundation of Mexican cooking. It is connecting with 3,500 years of Mesoamerican culinary wisdom. Explore our recipes to put your homemade masa into practice, and find lime and corn for nixtamal in our directory of Mexican shops. You can also visit Mexican restaurants that nixtamalise their own corn - they are the ones serving the best tortillas.