Nixtamalization is a traditional process that consists of an alkaline cooking of the corn grain, resting, rinsing and grinding. The nixtamalization process increases the nutritional quality of the grain by increasing the availability of protein and calcium, in addition to being the main process for the preparation of everyday foods in Mexico, such as tortillas.

The word nixtamalization comes from the Nahuatl nextli, ash lime, and tamalli, cooked corn dough; "ash and mass". The antiquity of the process is deduced through the evidence of the vestiges that have been recovered in the archaeological zones. Comales are found from the Preclassic period in the Central Plateau of Mexico and from centuries before Christ, in the Maya area, the Huastecas, Oaxaca, towns of the coast of the Gulf of Mexico and Aridoamérica. The highest frequency of comales in the archaeological record coincides with the rise of the Teotihuacano and Tepaneco-Mexica empires (Fournier, 1998; Herrera-Villalobos, 2004).

Nixtamalization is a traditional process that begins when the corn grain is cooked with lime (1% lime to corn ratio) for 40 to 90 minutes. Once cooked, it is left to rest in the cooking water for 8 to 18 hours, so that the grains soften and loosen the shell. Finally, the nixtamal is ground in a mill or metate to obtain the dough (Paredes et al., 2009; Figueroa, 2010). In some places, nixtamal is usually made with the ash obtained from the embers of the stove or tequesquite.

This traditional process is carried out manually and in small quantities on a daily basis in rural families, and it does not seem to be important, it is seen as one more chore in the kitchen, however, it is a transcendental process for Mexicans.

The benefits of the nixtamalization process focus on modifying the nutritional quality of the grain and functional properties in the tortilla. a) increase in amino acids; lysine by 2.8-fold, isoleucine to leucine ratios are increased 1.8-fold and niacin is released which prevents pellagra and increases the bioavailability of essential amino acids. b) increased calcium in the diet, which reduces the risk of osteoporosis, a disease that manifests itself as bone fragility due to loss of mass in the bone system. c) improves shelf life, since it inhibits microbial activity with the partial destruction of aflatoxins in corn contaminated by Aspergillus flavus that produces mold (Gómez-Aldapa et al., 1996; Katz 1974; Reyes et al., 1998 ;Figueroa, 2010).

Likewise, when nixtamalization is done on a small scale, the nejayote (water with lime or ash in which the corn has been cooked) contains a high concentration of soluble solids and lime, it is a useful resource, to feed pigs or to harden floors ( Elias-Orozco et al., 2002).

Mexico gave the world corn, since it is the center of origin and diversification of the grain, but not nixtamalization. It is known that, during the conquest, the Spanish took the corn, but they were unaware of the nixtamalization process. The consumption of corn without nixtamalized increased the susceptibility of getting pellagra, a disease related to the lack of niacin or Vitamin B3. While this did not occur with the Indians of New Spain due to nixtamalization, which increases the bioavailability of niacin (Bressani and Scrimshow, 1958).

Thanks to the nixtamalization process, in Mexico you can prepare various foods from corn dough such as; tortillas, tamales, atoles, gorditas, tlacoyos, broths, etc. Nixtamalization provides appreciable characteristics to the tortilla such as color, flavor, smell and texture, due to the reactions developed during alkaline cooking that break down the amino acid tryptophan in the corn, producing the typical smell and flavor. Variations in the process provide quality to food. For example, nixtamal with ash is prepared for specific foods such as corundas from Michoacán and tejate in Oaxaca. If it is cooked until the grain bursts, or if it is cooked and after resting, it is cooked again, they are variations for different types of toast in Chiapas.

The nixtamalization process has been widely studied in its production for the tortilla industry, due to the negative impacts on the environment, when it is done massively to feed the population concentrated in the cities, due to the amount of water, lime and energy required on a large scale. Ways are being sought to use less lime and water, as well as less cooking time to save energy, in addition to reducing the amount of waste or taking advantage of nejayote for other industrial uses due to its high gum content (Figueroa, 2010).