Maize — or corn, as it's called in English-speaking North America — is a strain of wild grass that does not grow in the wild. It must be domesticated and cared for to survive. Maize is one of the most culturally significant crops throughout the Southwest and much of Latin America, particularly Mexico. But it's cultivated throughout the world, making corn and its related products one of the most common foods on earth.
There is much debate over which grass maize evolved from or who created the hybrid, but corn cobs have been found in archaeological excavations dating to 5000 BC. It certainly has been cultivated in what is now Mexico for almost 10,000 years. The earliest inhabitants of the region considered maize one of the all-important crops known as "the three sisters," along with winter squash and climbing beans.
Three main types of agricultural corn account for the majority of culinary uses. Many varieties cross-pollinate, however, producing corn with a mix of kernel characteristics.
- Sweet corn is so called because is it actually has more sugar and less starch than other varieties of maize. It is almost always eaten fresh, either on the cob or off, or preserved by canning or freezing.
- Dent corn is also known as field corn; it can be yellow or white. White dent corn has a higher percentage of starch than the yellow variety and is the best corn for making masa dough and hominy. It is also widely used as livestock feed and in processed foods, plastics, and fuels.
- Flint corn, also known as blue or red corn or Indian corn, is cultivated mainly in Central and South America. It has a hard exterior and is used for both human consumption and animal feed. Popcorn is sometimes considered a sub-set of flint corn, but no matter its classification, it's a particular type of kernel that explodes when heated.
Other types of corn also exist, including flour corn, a white, particularly soft corn used for making corn flour for baked goods, and pod corn, an ornamental variety.
Hominy (Pozole) and Masa
The form of maize most used in Mexican cuisine is dent corn that has undergone the nixtamalición process. First, the kernels are removed from the cob and dried. The dried kernels are boiled in water that contains cal, or slaked lime. The kernels are often left to soak in the water for 1 hour to 24 hours, depending on the intended use.
At this stage, the corn is called nixtamal. Next, the kernels are rinsed thoroughly and rubbed together to remove the skins. For hominy, the little brown tips, or "hulls," are picked off; this allows the corn to expand greatly when cooked. Ground nixtamal becomes masa, the corn dough that will eventually be made into tortillas, tamales, and other delicious items.
Masa harina, or dough flour, is made from nixtamal. After the hulls are removed, the kernels are ground into masa, which is then dehydrated. The dried dough is ground again into a very fine flour that can be packaged and kept shelf stable for a long time.
Masa harina needs to be mixed with water or another liquid to form a dough, which can be used to make tortillas, tamales, and other dishes.
Corn starch is the very finely ground white powder made from grinding the starchy part of maize kernels. It is most often used in baked goods and as a thickener for some sauces and cream soups. The proper name for corn starch in Spanish is fécula de maíz, but colloquially it is most often called Royal, after a very popular brand name of this product. Corn starch is called corn flour in the United Kingdom.
Sweet corn that has been dried and ground to a coarse flour is known as cornmeal. If the hulls (skins) and germs (brown tips) are removed, the meal will have a long shelf life; if the hulls and germs remain in the meal, it is more nutritious, but it won´t keep as long. Cornmeal is used as a hot cereal or made into “grits” by adding boiling water to make a mush. It is also used to make cornbread and polenta.
Corn flour is made by grinding up dried corn into a very fine flour. It is used in many of the same ways a wheat flour is used. (In the United Kingdom, the term corn flour refers to what is called corn starch in North America.)
Cornmeal and corn flour are rarely used in authentic Mexican cuisine, though they are common in the cuisine of the American Southwest.