Nixtamalization is a centuries-old technique for enhancing the nutritional value and digestibility of maize (Zea mays), and to a lesser extent, sorghum (Sorghum bicolor) and other grains. It involves boiling and soaking the grain in an alkaline solution before washing and then grinding it to make dough for tortillas and other products. This article will introduce the history and benefits of nixtamalization, explain the process, and discuss related options.

History

Archeological studies have shown that nixtamalization is a pre-Hispanic practice that originates in Mesoamerica (Dezendorf, 2013). Historically, nixtamalization has been done using wood ash; however, according to Santiago-Ramos et al. (2018) the use of wood ash1 has largely been replaced with that of lime (calcium hydroxide) and other compounds such as sodium hydroxide and potassium hydroxide. 

Benefits

The high pH of lime and other alkaline compounds breaks down the seed hull and pericarp in grain, changing the starchy endosperm of the maize grains and helping to “pre-digest” nutrients, making them more available during digestion. Changes in the starchy endosperm make the dough, often called masa, easier to roll in making tortillas. A tortilla should be easy to fold and roll, and not split when eaten or filled. 

The lime used in nixtamalization also increases calcium and reduces mycotoxins (molds) in nixtamalized grain. Wacher (2003) mentioned that the increased calcium from cooking with lime-water is important in countries where access to dairy products is limited. The reduction in mycotoxins has implications for relief organizations looking for ways to reduce aflatoxins in stored maize for their emergency response efforts. The alkaline solution used in nixtamalization reduces aflatoxins (Matendo et al., 2023), meeting EU standards in East Africa, improving nutrition, and reducing mycotoxins (Odukoya et al., 2021).

There can be losses of some nutritional components, such as thiamin (vitamin B1), riboflavin (vitamin B2), and niacin (vitamin B3) (Wacher, 2003). Losses, however, should be considered in light of increased availability of nutrients to the human body. Maize is typically rich in niacin, but most of it is not bioavailable for human use (Kamau et al., 2020; Wacher, 2003). Nixtamalization releases the previously bound niacin, making it easier for the body to absorb. The most extreme example of a severe deficiency of niacin is pellagra (Rabinowitz, 2023); this condition was not common in Mesoamerica (Wacher, 2003) where nixtamalization originated. 

Process

To make the alkaline solution for nixtamalization, use a food grade form of lime. The traditional nixtamalization process, as described by Enriquez-Castro et al. (2023), entails the following steps:

1. 

   Boil whole (instead of ground) kernels of grain in a lime solution consisting of 3 parts lime-water to 1 part grain for 30 to 60 minutes. You can optimize cooking time based on seed coat hardness of the grain being used. The amount of lime to use in the lime-water should be 1% to 3% of the weight of the grain. Stir the lime in hot water to avoid clumping.
2. Let the grain soak in the cooking water for up to 24 hours (commonly used steeping times are 8 to 12 hours or overnight; Figure 1).
3. Drain the cooking water, referred to as nejayote, leaving behind the soaked grain referred to as nixtamal. 
4. Wash the nixtamal to remove loosened pericarp and excess lime.
5. The nixtamalized grains are now ready to be ground and made into flour or other products such as dough for tortillas.

Options for improvement and mass production

Different maize varieties and the growing conditions affect nixtamalization (Ramírez-Vega et al., 2022) and tortilla quality made from nixtamalized grain. Specific maize breeding to improve the nutritional value of maize resulted in Quality Protein Maize (QPM) with increased lysine, tryptophan, and zinc. The possibility for improved, open-pollinated varieties through breeding offers small-scale farmers more ways to improve tortilla-based diets. 

Additions to nixtamalized tortillas included soybean (Glycine max) as part of a ready-made commodity corn-soy blend CSB (USAID, 2012) for more industrial production. Relief agencies, such as USAID and the World Food Program, use CSB to ease malnutrition. For small-scale farmers, other easy-to-grow ingredients can include chía (Salvia hispanica) (Rendón-Villalobos et al., 2012), chaya (Cnidoscolus aconitifolius; Miracles in Action, 2019 and video here [http://edn.link/rnzen3]), and chipilín (Crotalaria longirostrata; Guzmán, 2022).

Though the chemical principles of nixtamalization remain the same since pre-Hispanic times, industrial production of tortilla products adapted for efficiency in meeting modern consumers’ demand for basic properties, such as foldability, rollability, texture, and flavor, of tortillas available in supermarkets and local stores. One adaptation is the use of calcium salts like calcium chloride that, unlike lime, will not produce high-pH cooking water, the disposal of which is an ecological concern from the standpoint of its effect on soil pH. 

Another way to use less water and lime is to use a process called extrusion nixtamalization in which grain cooked in a slurry of lime and water Is subjected to heat and pressure using a mechanical device like that shown in Figure 2. Extrusion technologies vary in complexity and cost. The nixtamalization step prior to extrusion addresses concerns that mechanically produced tortillas have less nutrient bioavailability (USAID, 2012) and overall quality (Enríquez-Castro et al., 2020) than tortillas produced with traditional nixtamalization described earlier in this article. See research reports by Kamau et al. (2020) and Enriquez-Castro et al. (2023) for more detailed information comparing traditional nixtamalization with extrusion methods.

Closing thoughts

From pre-Hispanic to modern times, nixtamalization improves maize-based diets while protecting grain from mycotoxins and maintaining natural flavors through the practical application of basic food chemistry. For a helpful review of nixtamalization, watch a video from the International Center for Improving Maize and Wheat, CIMMYT here: http://edn.link/7dmx3c

References