Field corn grain is dried and then treated by cooking the mature, hard grain in a diluted solution of
slaked lime (calcium hydroxide) or
wood ash, and then letting it soak for many hours. The soaked maize is then rinsed thoroughly to remove the unpalatable flavor of the alkali. This process is
nixtamalization, and it produces
hominy, which is ground into a relatively dry dough to create
fresh masa. The fresh masa can be sold or used directly, or can be dehydrated and blended into a powder to create
masa harina, or masa flour. 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 corn. Some of the corn oil is broken down into emulsifying agents (monoglycerides and diglycerides), while bonding of the corn 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. The chemical changes in masa allow dough formation, and also allow the nutrient
niacin to be absorbed by the digestive tract. By contrast, untreated
cornmeal is unable to form a dough on the addition of water, and a diet heavily reliant on its consumption is a risk factor for
pellagra. ==Other uses==