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Nixtamalization () is a process for the preparation of
corn Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...
, or other
grain A grain is a small, hard, dry fruit ( caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legum ...
, in which the grain is soaked and cooked in an
alkaline In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...
solution, usually
limewater Limewater is the common name for a saturated aqueous solution of calcium hydroxide. Calcium hydroxide, Ca(OH)2, is sparsely soluble at room temperature in water (1.5 g/L at 25 °C). "Pure" (i.e. less than or fully saturated) limewater i ...
(but sometimes aqueous
alkali metal The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...
carbonate A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...
s), washed, and then hulled. The term can also refer to the removal via an alkali process of the pericarp from other grains such as
sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many other ...
. Nixtamalized corn has several benefits over unprocessed grain: It is more easily ground, its
nutrition Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain sufficient ...
al value is increased, flavor and
aroma An odor (American English) or odour (Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their sens ...
are improved, and
mycotoxin A mycotoxin (from the Greek μύκης , "fungus" and τοξίνη , "toxin") is a toxic secondary metabolite produced by organisms of kingdom Fungi and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' ...
s are reduced by up to 97%–100% (for aflatoxins). Lime and ash are highly alkaline: the alkalinity helps the dissolution of hemicellulose, the major glue-like component of the maize cell walls, and loosens the hulls from the kernels and softens the maize. Corn's hemicellulose-bound
niacin Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
is converted to free niacin (a form of vitamin B3), making it available for absorption into the body, thus helping to prevent pellagra. Some of the corn oil is broken down into emulsifying agents (monoglycerides and diglycerides), while bonding of the maize proteins to each other is also facilitated. The divalent calcium in lime acts as a cross-linking agent for protein and polysaccharide acidic side chains. As a result, while
cornmeal Cornmeal is a meal (coarse flour) or a cell membrane ground from dried corn. It is a common staple food, and is ground to coarse, medium, and fine consistencies, but not as fine as wheat flour can be.Herbst, Sharon, ''Food Lover's Companion'', ...
made from untreated ground maize is unable by itself to form a dough on addition of water, the chemical changes in '' masa'' allow dough formation. These benefits make nixtamalization a crucial preliminary step for further processing of maize into food products, and the process is employed using both traditional and industrial methods, in the production of
tortilla A tortilla (, ) is a thin, circular unleavened flatbread originally made from maize hominy meal, and now also from wheat flour. The Aztecs and other Nahuatl speakers called tortillas ''tlaxcalli'' (). First made by the indigenous peoples of M ...
s and
tortilla chip A tortilla chip is a snack food made from corn tortillas, which are cut into triangles and then fried or baked (alternatively they may be discs pressed out of corn masa then fried or baked). Corn tortillas are made of nixtamalized corn, vege ...
s (but not
corn chip Corn chips are a snack food made from cornmeal fried in oil or baked, usually in the shape of a small noodle or scoop. Corn chips are thick, rigid and very crunchy. Corn chips have the strong aroma and flavor of roasted corn, and are often heavi ...
s),
tamale A tamale, in Spanish tamal, is a traditional Mesoamerican dish made of masa, a dough made from nixtamalized corn, which is steamed in a corn husk or banana leaf. The wrapping can either be discarded prior to eating or used as a plate. Tam ...
s,
hominy Hominy (Spanish: maíz molido; literally meaning "milled corn") is a food produced from dried maize (corn) kernels that have been treated with an alkali, in a process called nixtamalization ( is the Nahuatl word for "hominy"). "Lye hominy" is a ...
, and many other items.


Etymology

In the
Aztec The Aztecs () were a Mesoamerican culture that flourished in central Mexico in the post-classic period from 1300 to 1521. The Aztec people included different ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl ...
language
Nahuatl Nahuatl (; ), Aztec, or Mexicano is a language or, by some definitions, a group of languages of the Uto-Aztecan language family. Varieties of Nahuatl are spoken by about Nahua peoples, most of whom live mainly in Central Mexico and have small ...
, the word for the product of this procedure is or ( or ), which in turn has yielded
Mexican Spanish Mexican Spanish ( es, español mexicano) is the variety of dialects and sociolects of the Spanish language spoken in Mexican territory. Mexico has the largest number of Spanish speakers, with more than twice as many as in any other country in ...
(). The Nahuatl word is a compound of " lime ashes" and "unformed/cooked corn dough,
tamal A tamale, in Spanish tamal, is a traditional Mesoamerican dish made of masa, a dough made from nixtamalized corn, which is steamed in a corn husk or banana leaf. The wrapping can either be discarded prior to eating or used as a plate. Tamale ...
". The term ''nixtamalization'' can also be used to describe the removal of the pericarp from any grain by an alkali process, including maize,
sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many other ...
, and others. When the unaltered Spanish spelling is used in written English, however, it almost exclusively refers to maize. The labels on packages of commercially sold tortillas prepared with nixtamalized maize usually list ''corn treated with lime'' as an ingredient in English, while the Spanish versions list .


History


Mesoamerica

The process of nixtamalization was first developed in
Mesoamerica Mesoamerica is a historical region and cultural area in southern North America and most of Central America. It extends from approximately central Mexico through Belize, Guatemala, El Salvador, Honduras, Nicaragua, and northern Costa Rica. Wit ...
, where
maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American English, North American and Australian English), is a cereal grain first domesticated by indigenous peoples of Mexico, indigenous ...
was originally cultivated. There is no precise date when the technology was developed, but the earliest evidence of nixtamalization is found in Guatemala's southern coast, with equipment dating from 1200–1500 BC. How nixtamalization was discovered is not known, but one possibility may have been through the use of hot stones (see Pot boiler) to boil corn in early cultures which did not have cooking vessels robust enough to put directly on fire or coals. In limestone regions like those in Guatemala and southern Mexico, heated chunks of limestone would naturally be used, and experiments show that hot limestone makes the cooking water sufficiently alkaline to cause nixtamalization. Archaeological evidence supporting this possibility has been found in southern Utah, United States. The
Aztec The Aztecs () were a Mesoamerican culture that flourished in central Mexico in the post-classic period from 1300 to 1521. The Aztec people included different ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl ...
and
Mayan Mayan most commonly refers to: * Maya peoples, various indigenous peoples of Mesoamerica and northern Central America * Maya civilization, pre-Columbian culture of Mesoamerica and northern Central America * Mayan languages, language family spoken ...
civilizations developed nixtamalization using slaked lime (
calcium hydroxide Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca( OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed or slaked with water. It has ma ...
) and lye (
potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exp ...
) to create alkaline solutions. The
Chibcha The Muisca (also called Chibcha) are an indigenous people and culture of the Altiplano Cundiboyacense, Colombia, that formed the Muisca Confederation before the Spanish conquest. The people spoke Muysccubun, a language of the Chibchan lan ...
people to the north of the ancient
Inca The Inca Empire (also known as the Incan Empire and the Inka Empire), called ''Tawantinsuyu'' by its subjects, ( Quechua for the "Realm of the Four Parts",  "four parts together" ) was the largest empire in pre-Columbian America. The adm ...
also used calcium hydroxide (also known as "cal"), while the tribes of North America used
soda ash Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...
. The nixtamalization process was very important in the early Mesoamerican diet, as most of the
niacin Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
content in unprocessed maize is bound to hemicellulose, drastically reducing its bioavailability. A population that depends on untreated maize as a
staple food A staple food, food staple, or simply a staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard Diet (nutrition), diet for a given person or group of people, supplying a large fraction of ...
risks malnourishment and is more likely to develop
deficiency disease Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues ...
s such as pellagra, niacin deficiency, or
kwashiorkor Kwashiorkor ( , ) is a form of severe protein malnutrition characterized by edema and an enlarged liver with fatty infiltrates. It is thought to be caused by sufficient calorie intake, but with insufficient protein consumption (or lack of go ...
, the absence of certain amino acids that maize is deficient in. Maize cooked with lime or other alkali provided bioavailable niacin to Mesoamericans. Beans provided the otherwise missing amino acids required to balance maize for complete protein. The spread of maize cultivation in the Americas was accompanied by the adoption of the nixtamalization process. Traditional and contemporary regional cuisines (including Maya cuisine, Aztec cuisine, and
Mexican cuisine Mexican cuisine consists of the cooking cuisines and traditions of the modern country of Mexico. Its earliest roots lie in Mesoamerican cuisine. Its ingredients and methods begin with the first agricultural communities such as the Olmec and ...
) included, and still include, foods based on nixtamalized maize. The process has not substantially declined in usage in the
Mesoamerican region The Mesoamerican region (often abbreviated MAR) is a trans-national economic region in the Americas that is recognized by the OECD and other economic and developmental organizations, comprising the united economies of the seven countries in Centr ...
, though there has been a decline in North America. Many North American Native American tribes, such as the
Huron Huron may refer to: People * Wyandot people (or Wendat), indigenous to North America * Wyandot language, spoken by them * Huron-Wendat Nation, a Huron-Wendat First Nation with a community in Wendake, Quebec * Nottawaseppi Huron Band of Potawato ...
, no longer use the process. In some Mesoamerican and North American regions, dishes are still made from nixtamalized maize prepared by traditional techniques. The
Hopi The Hopi are a Native American ethnic group who primarily live on the Hopi Reservation in northeastern Arizona, United States. As of the 2010 census, there are 19,338 Hopi in the country. The Hopi Tribe is a sovereign nation within the United ...
produce sodium carbonate from ashes of various native plants and trees. Some contemporary Maya use calcium salts in the form of ashes of burnt mussel shells or heated limestone. In the United States, European settlers did not always adopt the nixtamalization process, except in the case of hominy grits, though maize became a staple among the poor of the southern states. This led to endemic pellagra in poor populations throughout the southern US in the early 20th century. A more varied diet and fortification of wheat flour, the other staple food, have essentially eliminated this deficiency.


Process


Cooking

In the first step of nixtamalization, kernels of dried maize are cooked in an alkaline solution at or near the mixture's boiling point. After cooking, the maize is steeped in the cooking liquid for a period. The length of time for which the maize is boiled and soaked varies according to local traditions and the type of food being prepared, with cooking times ranging from a few minutes to an hour, and soaking times from a few minutes to about a day. During cooking and soaking, a number of chemical changes take place in the grains of maize. Because plant cell wall components, including hemicellulose and
pectin Pectin ( grc, πηκτικός ': "congealed" and "curdled") is a heteropolysaccharide, a structural acid contained in the primary lamella, in the middle lamella, and in the cell walls of terrestrial plants. The principal, chemical component o ...
, are highly soluble in alkaline solutions, the kernels soften and their pericarps (hulls) loosen. The grain hydrates and absorbs calcium or
potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmos ...
(depending on the alkali used) from the cooking solution. Starches swell and gelatinize, and some starches disperse into the liquid. Certain chemicals from the germ are released that allow the cooked grains to be ground more easily, yet make dough made from the grains less likely to tear and break down. Cooking changes the grain's protein matrix, which makes proteins and nutrients from the
endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the embryo an ...
of the kernel more available to the human body.


Extraction

After cooking, the alkaline liquid (known as nejayote), containing dissolved hull, starch, and other corn matter, is decanted and discarded (or sometimes used for making
amate Amate ( es, amate from nah, āmatl ) is a type of bark paper that has been manufactured in Mexico since the precontact times. It was used primarily to create codices. Amate paper was extensively produced and used for both communication, record ...
bark paper). The kernels are washed thoroughly of remaining nejayote, which has an unpleasant flavor. The pericarp is then removed, leaving the
endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the embryo an ...
of the
grain A grain is a small, hard, dry fruit ( caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legum ...
with or without the
germ Germ or germs may refer to: Science * Germ (microorganism), an informal word for a pathogen * Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually * Germ layer, a primary layer of cells that forms during embryo ...
, depending on the process. This hulling is performed by hand, in traditional or very small-scale preparation, or mechanically, in larger scale or industrial production. The prepared grain is called hominy or nixtamal. Nixtamal has many uses, contemporary and historic. Whole nixtamal may be used fresh or dried for later use. Whole nixtamal is used in the preparation of
pozole Pozole (; from nah, pozoll, meaning ''cacahuazintle'', a variety of corn or maize) is a traditional soup or stew from Mexican cuisine. It is made from hominy with meat (typically pork, but possibly chicken), and can be seasoned and garnished w ...
, menudo, and other foods. Ground fresh nixtamal is made into ''masa'' (nixtamal
dough Dough is a thick, malleable, sometimes elastic paste made from grains or from leguminous or chestnut crops. Dough is typically made by mixing flour with a small amount of water or other liquid and sometimes includes yeast or other leavenin ...
) and used to make
tortilla A tortilla (, ) is a thin, circular unleavened flatbread originally made from maize hominy meal, and now also from wheat flour. The Aztecs and other Nahuatl speakers called tortillas ''tlaxcalli'' (). First made by the indigenous peoples of M ...
s,
tamale A tamale, in Spanish tamal, is a traditional Mesoamerican dish made of masa, a dough made from nixtamalized corn, which is steamed in a corn husk or banana leaf. The wrapping can either be discarded prior to eating or used as a plate. Tam ...
s, and
arepa ''Arepa'' () is a type of food made of ground maize dough stuffed with a filling, eaten in the northern region of South America since pre-Columbian times, and notable primarily in the cuisine of Colombia and Venezuela, but also present in the cuis ...
s. Dried and ground, it is called ''masa harina'' or instant ''masa'' flour, and is reconstituted and used like ''masa''. The term hominy may refer to whole, coarsely ground, or finely ground nixtamal, or to a cooked porridge (also called samp) prepared from any of these.


Enzymatic nixtamalization

An alternative process for use in industrial settings has been developed known as enzymatic nixtamalization, which uses
protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...
enzymes to accelerate the changes that occur in traditional nixtamalization, a technique borrowed from modern
corn wet-milling Corn wet-milling is a process of breaking corn kernels into their component parts: corn oil, protein, corn starch, and fiber. It uses water and a series of steps to separate the parts to be used for various products. History The corn wet-milling ...
. In this process, corn or corn meal is first partially hydrated in hot water, so that enzymes can penetrate the grain, then soaked briefly (for approximately 30 minutes) at in an alkaline solution containing protease enzymes. A secondary enzymatic digestion may follow to further dissolve the pericarp. The resulting nixtamal is ground with little or no washing or hulling. By pre-soaking the maize, minimizing the alkali used to adjust the pH of the alkaline solution, reducing the cooking temperature, accelerating processing, and reusing excess processing liquids, enzymatic nixtamalization can reduce the use of energy and water, lower nejayote (alkaline wastewater) production, decrease maize lost in processing, and shorten the production time (to approximately four hours) compared to traditional nixtamalization. Effects of enzymatic nixtamalization on flavor, aroma, nutritional value, and cost, compared to traditional methods, are not well documented.


Impact on health

The primary nutritional benefits of nixtamalization arise from the alkaline processing involved. These conditions convert corn's hemicellulose-bound niacin ("niacytin") to free niacin, making it available for absorption into the body, thus helping to prevent pellagra. Secondary benefits can arise from the grain's absorption of minerals from the alkali used or from the vessels used in preparation. These effects can increase
calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...
(by 750%, with 85% available for absorption),
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
,
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
, and
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
. Lastly, nixtamalization significantly deactivates (by 90–94%)
mycotoxin A mycotoxin (from the Greek μύκης , "fungus" and τοξίνη , "toxin") is a toxic secondary metabolite produced by organisms of kingdom Fungi and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' ...
s produced by '' Fusarium verticillioides'' and ''
Fusarium proliferatum ''Fusarium proliferatum'' is a fungal A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are cl ...
'', molds that commonly infect maize, the toxins of which are putative
carcinogens A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...
.


References

*Coe, Sophie. America's First Cuisines (1994). *Davidson, Alan. Oxford Companion to Food (1999), “Nixtamalization”, p. 534. *Kulp, Karen and Klaude J. Lorenz (editors). Handbook of Cereal Science and Technology (2000), p. 670. *McGee, Harold. On Food and Cooking, 2nd Edition (2004) p. 477-478
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 {{Cooking techniques Cooking techniques Mexican cuisine Mesoamerican cuisine Maize Food science de:Mais#Nixtamalisation