Nixtamalization

Nixtamalization is a process whereby dry maize grain is soaked and cooked in an alkaline solution, usually limewater, to cause the transparent outer hull, the pericarp, to separate and be removed from the grain. This process has several benefits including enabling the grain to be more effectively ground; increasing protein and vitamin content availability; improving flavor and aroma and reduction of mycotoxins. In the Aztec language Nahuatl, the word for the product of this procedure is nixtamalli or nextamalli ( or ), which in turn has yielded Mexican Spanish nixtamal ( or ). The Nahuatl word is a compound of nextli "ashes" and tamalli "unformed corn dough, tamal." The term nixtamalization (spelled with the "t") can also be used to describe the removal of the pericarp from any grain such as sorghum by an alkali process. When the unaltered Spanish spelling nixtamalizacion is used in written English, however, it almost exclusively refers to maize.

History
The ancient process of nixtamalization was first developed in Mesoamerica, where maize 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. The ancient Aztecs and Mayans developed nixtamalization; the Chibcha people to the north of the ancient Inca used "cal" as well as when cooking.

The ancient Maya and the Aztecs used lime (calcium oxide, not to be confused with the citrus fruit of the same name) and ashes in creating alkaline solutions, while the tribes of North America used sodium carbonate, which occurred naturally, or ashes. The nixtamal process was very important in the early Mesoamerican diet as maize, one of the so-called Three Sisters of agriculture along with beans and squash, was deficient in essential amino acids and in niacin. A population depending on untreated maize as a staple food would be malnourished and develop the deficiency disease known as pellagra. Cooking with lime enables a balance of essential amino acids and makes available niacin. Without the use of nixtamalization, civilization in Mesoamerica would not have existed. In these early civilizations the process of nixtamalization was distinctive in that hard, ripe kernels were boiled in water and lime, thus producing nixtamal which was then made into unleavened dough for flat cakes by grinding with a handstone on a quern-stone (metate).

The process has not substantially declined in usage in the Mesoamerican region though there has been a decline in North America.

Europe
Maize was introduced to Europeans 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 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 decanting the soaking liquid and washing the grains. The cooking in alkaline solution removes certain starch granules and makes 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, known as najayote and pericarp. The prepared grain now called nixtamal is then ground while the removed pericarp is used traditionally to feed pigs if this process is done in rural areas.

The Americas
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.

The U.S. version of hominy is produced by whole maize grains, usually white when eaten in the form of grits, mixed with scalding water mixed with a chemical solution, such as a mild lye 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.

Many companies selling tortillas in the United States use nixtamalizacion as part of their process. In English their labels usually list "corn treated with lime" as an ingredient, while the Spanish versions list maiz nixtamalizado. This is because the word is more well-known in Spanish than it is in English.

Contemporary Native Americans
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 Hopi obtain the necessary alkali from ashes of various native bushes or wood (typically the juniper tree)  Contemporary Maya use the ashes of burnt mussels.

Alternative process
An alternative process has been developed known as enzymatic nixtamalization which produces instant masa flour while reducing the nejayote or alkaline waste water that is produced during traditional nixtamal production. The process consists of whole kernel corn being cooked in water without any lime or alkaline substances and water from the initial cooking stage is re-used in subsequent washings or cookings. The cooked corn is steeped or soaked in a lime solution (.05%) at 50-60C for three to four hours where the acidity of the solution increases. After decanting, the corn kernels are ground coarsely and then dried for milling into masa flour. After milling additional substances, like lime, can be added to produce more traditional taste profiles. The benefits of this process is the reduction of waste water; quicker production time; reduced corn solid loss (2% as opposed to 5-14%) and reduced amounts of lime use.

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 may be 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 fumonisins 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.