Masa: Nixtamalization, Tortillas, and Mycotoxins

When we were asked if we could adapt our mycotoxin strips to detect Aflatoxin and Fumonisin in masa, we learned all about how corn becomes masa. Though in general we know masa is used to make tortillas, what we found was a fascinating process that traces its roots into ancient Mesoamerica. Thought to have developed as a means of making corn more grindable, it also confers nutritional and even safety benefits to the resulting product.

Boiling corn in water along with an alkali agent is known as Nixtamalization (NEESH-tamali-ZAY-shun). The alkali causes biochemical transformation which not only removes the indigestible pericarp portion of the corn kernel but also makes calcium and niacin (vitamin B3) bioavailable.

As corn was developed and spread throughout the Americas, different native populations used variations of this process on their corn products. Whether from ash (potash, potassium hydroxide) or mineral lime (calcium hydroxide), nixtamalization is traceable through Aztec, Inca, Maya, and Native American populations. Here in the Eastern US, the first colonists noted that Native Americans cooked corn with wood ash, but mistakenly thought it was simply for flavor (which they did not like), and dismissed its importance.

Columbus is credited with bringing corn back to the ‘old world,’ but unfortunately knowledge of the nixtamalization process did not go with it, likely because Europe was more advanced industrially and did not need to grind corn by hand. Although its popularity spread quickly throughout the continent and into Africa, many peasant populations that relied on corn when other staple crops failed are known to have suffered wasting diseases due to the ignorance of how to release corn’s nutritional value.

This also affected the American South during the Great Depression; the population deriving from mainly European immigrants did not know the secret of unlocking corn’s maximum nutritional value, and over 100,000 deaths were directly attributed to pellagra, a chronic wasting disorder.

Its nutritional benefits well characterized, it is only recently that nixtamalization’s effect on mycotoxin contamination is becoming more understood, studied, and reported on. It is quite possible that the ancients knew nixtamalization made even ‘bad’ corn edible, and there are numerous scientific studies showing that mycotoxin loads in masa after nixtamalization are lower than in the initial corn, while steep water (nejayote) and the removed portions of corn (pericarp) have shown increased loads.

While it appears possible to reduce mycotoxin loads when making masa, it is still important that processors screen incoming corn for Aflatoxin and Fumonisin to ensure the performance and safety compliance of the finished product, be it tortilla, posole, or other item. And now corn processors have another tool to ensure safety compliance by testing their product within or at the end of the nixtamalization process.


Additional definitions and background:

Nixtalamize (neesh-TA-malize)

Masa ready to be turned into tortillas, photo by Kevin Kramer, courtesy of The Growler

The origin of the nixtamilization of corn is about 1500 BC–1200 BC; somewhere in the Aztec empire, they happened upon it. Of course no one really knows how it started, treating the kernels with alkalis. You could either use pure calcium hydroxide from the earth, mineral lime called “cal,” or potash (potassium hydroxide), the ash from burning plants, and heat it with corn and let it soak.
Read more at The Growler.

Tortilla (tor-TEE-uh)

Totilla – a name given by the Spaniards to the unleavened flat bread they found in Mexico among the Aztec in the sixteeth century. The world “tortilla” comes from the Spanish word “torta” which means round cake.
Read more at La Tortilla Oven

Mycotoxins During the Processes of Nixtamalization and Tortilla Production, Sara Schaarschmidt and Carsten Fauhl-Hassek

Alkaline cooking of maize causes several physical, as well as (bio)chemical, changes [14,15]. Some of those are associated with the enhanced nutritional value of the grain and are of particular importance in diets mainly relying on maize. The improved bioaccessibility of calcium and niacin (vitamin B3) are likely the most important of these changes.
Read more at National Center for Biotechnology Information

Everything You Ever Needed to Know About Nixtamalization But Didn’t Know to Ask, by Dr. Rachel V. Briggs

Composition of a maize kernel, courtesy of All Things Hominy.

Maize, like many New World food items, was rapidly assimilated into the culinary traditions of Europe, becoming common place within only a few decades after Columbus’s first trip…Nixtamalization is a culinary technique that utilizes an alkaline substrate in order to process and cook maize. The practice itself involves soaking dried maize kernels to a solution made from water and an alkaline substrate, like limestone or lye, then cooking the kernels, or boiling the kernels in an alkaline solution for several hours.
Read more at All Things Hominy

Corn History: Everything Starts with Corn, by Azteca Milling

Ancient Aztecs were so highly dependent on corn that they worshipped Centeotl, the goddess of corn. To the Aztecs, Centeotl symbolized corn, a vitally important food crop that was also resistant to disease and freezing temperatures…It was during this time that ancient Aztecs began making tortillas. The Aztecs discovered that ashes from cooking fires mixed with water created an alkaline lime mixture that softened, partially dissolved, and helped remove the kernel’s tough outer skin, making corn easier to cook and make into masa (dough). Thus began the process now known as nixtamalization.
Read more at Azteca Milling

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