Nixtamal - Hominy
[Nixtamalized Corn (maize); Nixtamal (Spanish); Nixtamalli (Nahuatl); Hominy (North America, from Powhatan tribe)]
Corn for tortillas, tamales, soups and similar uses is nixtamalized to remove the hard outer skin from the kernels. This product is made by soaking dried corn in a strong alkali, lye-water (US) or lime-water (Mexico), until the outer hulls can be rubbed off. This process was first used about 3500 years ago in Guatemala, and has several nutritional advantages. It converts niacin into a form more readily absorbed by the body, improves digestibility of amino acids, and the lime treated version adds calcium to balance corn's excess of phosphorus. This can be made from yellow or white corn.
In the photo, white corn nixtamal, prepared with lime, was canned, thus it has been cooked to some extent. The fresh yellow nixtamal on the right has not been cooked at all and is intended for inclusion in Menudo and similar soups. Both white and yellow are also sold dried and broken (see "Buying" below).
Products subjected to nixtamalization are whole kernel corn, both fresh and dried, grits (cracked corn), corn meal (masa harina) and corn meal dough (masa). The photo to the left shows giant white cacahuazintle corn that has been nixtalized before drying. In the photo the kernels are dried and about 0.67 inches across. They will expand to a larger size when cooked.
Buying: Unfortunately, many "grits" and cornmeal products are not properly labeled as to whether they're just cracked or ground, or whether they have been nixtamalized first. There are other industrial methods for removing the outer skin, so its having been removed is not a good guide.
Some packages, particularly those in markets serving a Mexican community, will indicate they have been treated with lime or lye. These products are preferred for good nutrition.
Storing: Canned and dried products can, with proper storage conditions, be held for at least a year, though vitamin content will slowly decline. Fresh products such as fresh nixtamalized corn kernels and masa (corn flour dough) should be kept refrigerated and used within just a few days.
Preparing from Dried: Here we presume the kernels have already been nixtamalized before drying. This how dried giant white cacahuazintle corn is generally sold.
Preparing from whole (skin on) kernels: Here are the instructions adapted from Diana Kenedy's "The Cuisines of Mexico" for preparing from whole corn kernels. She presumes dried giant white cacahuazintle corn, but it should work with other sizes as well. Start two days ahead.
Health & Nutrition: When corn (maize) became a common crop worldwide, particularly for the poor, it brought with it a deadly disabling disease called Pellagra. This niacin deficiency disease was particularly severe in Spain, northern Italy and the US Southeast, and is still a problem in Africa, Indonesia and China. It is characterized by terrible skin lesions, sensitivity to sunlight, and a whole host of other symptoms, culminating in dementia and death.
This disease had not affected the native populations of the Americas because their corn was almost always nixtamalized before cooking. This process converts the niacin in corn to a form the human body can utilize.