Nixtamalization: tradition and nutrition
Nixtamalization is a traditional process that consists of 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. It is also the main process for the preparation of everyday foods in Mexico, such as tortillas.
The word nixtamalization comes from Nahuatl nextli, lime from ashes, and tamalli, cooked corn dough; "ash and dough". The antiquity of the process is deduced through the evidence of the vestiges that have been recovered in the archeological zones.
There are comales from the Pre-Classic in Mexico's Central Highlands and from centuries before Christ, in the Maya area, the Huastecas, Oaxaca, towns on the coast of the Gulf of Mexico, and Aridoamerica. The greatest frequency of comales in the archaeological record coincides with the rise of the Teotihuacan and Tepaneco-Mexican empires.
Nixtamalization is a traditional process that begins when the corn grain is cooked with lime (1% lime to a proportion of corn) 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 hull. 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 from the ash obtained from the coals of the fire 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 have any importance, it is seen as just another task in the kitchen, however, it is a transcendental process for Mexicans.
The benefits of the nixtamalization process are focused on modifying the nutritional quality of the grain and functional properties in the tortilla.
a) increase in amino acids; lysine by 2.8 times, isoleucine to leucine ratios are increased by 1.8 times, and niacin is released which prevents pellagra and increases the bioavailability of essential amino acids.
b) the increase of calcium in the diet, which reduces the risk of osteoporosis, a disease that manifests itself as the fragility of the bones by loss of mass of 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.
Also, when nixtamalization is done on a small scale, 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.
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 Spaniards took corn, but they were unaware of the nixtamalization process.
The consumption of corn without nixtamalization increased the susceptibility to pellagra, a disease related to the lack of niacin or vitamin B3. While this did not occur with the New Spain Indians due to nixtamalization, which increases the bioavailability of niacin.
Thanks to the nixtamalization process, a variety of foods can be prepared in Mexico from corn dough such as; tortillas, tamales, atoles, gorditas, tlacoyos, broths, etc.
Nixtamalization provides appreciable characteristics to the tortilla like color, flavor, smell, and texture, due to the reactions developed during the alkaline cooking that break the tryptophan amino acid in the corn-producing the typical smell and flavor.
The variations in the process provide quality to the food. For example, nixtamal with ash, is prepared for specific foods such as corundas in Michoacan and tejate in Oaxaca. If it is cooked until the grain is burst, or if it is cooked and after the rest, it is cooked again, these are variations for different types of toasts in Chiapas.
The process of nixtamalization has been widely studied in its production for the tortilla industry, due to the negative impacts to the environment, when this is done in a massive way to feed the population concentrated in the cities, because of 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 rubber content.
By Rosa María González Amaro