Nixtamalizationən/ typically refers to a process for the preparation of maize (corn), or other grain, in which the corn is soaked and cooked in an alkaline solution, usually limewater (but sometimes wood ashlye) washed, and then hulled. This process is known to remove up to 97–100% of aflatoxins from mycotoxin-contaminated corn. The term can also refer to the removal via an alkali process of the pericarp from other grains such as sorghum.
Nixtamalized maize has several benefits over unprocessed grain: it is more easily ground; its nutritional value is increased; flavor and aroma are improved; and mycotoxins are reduced. 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. 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 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 tortillas and tortilla chips (but not corn chips), tamales, hominy, and many other items.
In the Aztec language Nahuatl, the word for the product of this procedure is nixtamalli or nextamalli (pronounced [niʃtaˈmalːi] or [neʃtaˈmalːi]), which in turn has yielded Mexican Spanishnixtamal ([nistaˈmal]). The Nahuatl word is a compound of nextli "ashes" and tamalli "unformed corn dough, tamal." The term nixtamalization can also be used to describe the removal of the pericarp from any grain by an alkali process, including maize, sorghum, and others. When the unaltered Spanish spelling nixtamalización 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 maíz nixtamalizado.