Nixtamalization

Nixtamalization is the process whereby ripe maize grains are soaked and cooked in an alkaline solution, usually lime based, to cause the transparent outer hull, the pericarp, to separate from the grain. This process has multiple benefits including enabling the grain to be more effectively ground; increasing protein and vitamin content availability; improving flavor and aroma and reduction of mycotoxins. The recorded Aztec word for the product of this process is nixtamal. The term can also be used to describe the removal of the pericarp from any grain such as sorghum by an alkali process.

History

This ancient process was first developed in Mesoamerica where maize was developed. There is no precise date when the technology was developed though the earliest physical evidence points to Guatemala 1200-1500 BCE. The ancient Aztecs and Mayans developed nixtamalization but the ancient Inca did not.

Mesoamerica and North America

Earliest evidence of nixtamalization is found in Guatemala's southern coast with equipment dating from 1200–1500 BCE. The ancient Maya and the Aztecs used lime (calcium carbonate) and ashes in creating alkaline solutions, while the tribes of North America used sodium carbonate, which occurred naturally, or ashes. It is noted that contemporary Maya use the ashes of burnt mussels. The process has not really declined in usage in the Mesoamerican region though there has been a decline in North America. Many North American Native American tribes, such as the Huron no longer use the process; however residents of the Southeastern United States still produce and eat hominy. The U.S. version of hominy is produced by whole maize grains, preferably white when eaten in the form of grits, mixed with scalding water mixed with a chemical solution, such as a mild lye or slaked lime (sodium hydroxide or potassium hydroxide solution), traditionally derived from wood ash, until the soaking forces the kernel to expand so the hull and germ split. The kernel is removed and dried. After drying, the whole kernels are soaked in water and a solution mixed with limestone or wood ash is used to expand the kernels, which are then boiled. It is also prepared into grits which are dried ground hominy.

Europe

Maize was introduced by Christopher Columbus in the 15th century, with it being grown in Spain as early as 1498. Europeans accepted maize within a generation, but they did not adopt the nixtamalization process, perhaps because the Europeans had more efficient milling processes and so did not need to remove the pericarp. However, without the process maize is a much less beneficial foodstuff, leading to outbreaks of pellagra and kwashiorkor in areas where it became a staple grain, such as certain regions of Italy and Africa. Because of this lack of understanding of the importance of the processing, maize suffered the stigma of being an unhealthy grain that could stave off starvation but lead to malnourishment. For example, this is why polenta was considered the poor person’s food in Italy until its more recent increase in status as gourmet food.

Africa

Early evidence of maize occurs with the Portuguese who grew the plant in the Congo as early as 1560. Maize has been adapted as a major grain in parts of Africa. However, the nixtamalization process has not been widely adapted.

Production

Hemicellulose is one of the major components of plant cell walls and can be dissolved in alkaline solutions. This dissolving of the hemicellulose loosens the pericarp so it can be removed. The germ of the grain remains after the pericarp is removed by washing. The cooking in alkaline solution removes certain starch granules and changes to the protein matrix which allows the easier access to proteins and nutrients from the endosperm of the kernel.

Because of the soaking and cooking, the grains take in moisture and calcium from the solution and certain chemicals from the germ are released that allow the nixtamal to be ground more effectively and the final masa dough to be less likely to tear and break down.

Production in Mexico uses lime water (CaO 1% based on corn weight), boiled for a wide variety of time (a few minutes to an hour), soaked overnight, and then washed to remove solution and pericarp. The nixtamal is then ground.

Industrial production in Mexico falls into two categories: the family owned tortilla factory and large-scale flour production which can produce 30-80 tonnes per day. The family owned tortilla factory uses the traditional nixtamal method except with the addition of mechanical equipment such as rotary mills and tortilla makers, while large-scale production does extensive sorting, storing, conversion of maize to nixtamal, sprays or pressure washes, grinds, dries, sifts and regrinds before packing into bags.

In contrast in Guatemala the lime concentration varies from 0.17-.058 by weight and cooked from 46-67 minutes at 94C.

Nutritional and Health Benefits

The nutritional benefits are many with nixtamalization. Calcium is increased by 750% with 85% available for digestion. Other vital minerals increase as well including iron, copper and zinc which maybe due to the lime being used or the vessels being used to make nixtamal. Niacin is made available for digestion which would otherwise be inaccessible with non-processed maize. Another important aspect of this process’ benefit is the significant reduction (90-94%) of the mycotoxins Fusarium vierticilloides and Fusarium proliferatum which produce fumosins which cause disease in animals and possible carcinoma in humans.

If nixtamal is allowed to ferment, riboflavin, protein, and niacin increase further in addition to amino acids, such as tryptophan and lysine. It has been calculated that residents of rural Mexico acquire 50% of their daily protein and 70% of calories from nixtamal tortillas. Because of the importance of nixtamal to the diet, the Mexican government has mandated that nixtamal flour have further vitamin fortification with vitamins A and C, niacin, riboflavin, folic acid, iron and zinc.

References

• Coe, Sophie. America’s First Cuisines (1994). ISBN 029271159X
• Davidson, Alan. Oxford Companion to Food (1999), “Nixtamalization”, p. 534. ISBN 0192115790
• Kulp, Karen and Klaude J. Lorenz (editors). Handbook of Cereal Science and Technology (2000), p. 670. ISBN 0824783581
• McGhee, Harold. On Food and Cooking, 2nd Edition (2004) p.477-478 ISBN 0684800012
• Wacher Carmen “Nixtamalization, a Mesoamerican technology to process maize at small-scale with great potential for improvingthe nutritional quality of maize based foods” (2003)
• Food and Agricultural Organization, United Nations. Maize in Human Nutrition
• Smith, C. Wayne, Javier Betrán and E. C. A. Runge (editors). Corn: Origins, History and Technology (2004) p. 275 ISBN 0471411841