Corn

Corn, or maize, is a tall annual grass that can reach several metres, producing one or more ears wrapped in husks. Each ear carries hundreds of kernels in neat rows, attached to a central cob. Kernels may be yellow, white, red, blue, purple or speckled, and each is a seed with starchy endosperm and a germ.

Major types include dent corn, the main field and feed type; flint corn, with hard kernels used for polenta and in Latin America; flour corn, soft and starchy; sweet corn, eaten fresh; and popcorn, whose hard, moist kernels burst when heated. Corn is sold as whole kernels, cornmeal, grits, masa, flour, starch, syrup and oil.

Maize was domesticated in southern Mexico, in the Balsas River valley, from a wild grass called teosinte roughly nine thousand years ago. Early farmers selected plants with larger, softer ears, and the crop gradually spread through Mesoamerica and the Americas.

The English word maize comes from the Spanish maiz, borrowed from mahiz in the Taino language of the Caribbean. In North America the word corn, originally meaning grain in general, came to mean maize alone. Different Indigenous peoples have countless names, such as Nahuatl tlaolli and Hopi qa'ö.

Maize underpinned the great civilizations of the Americas. Mesoamerican farmers developed nixtamalization, soaking and cooking the grain in alkaline water, usually lime or wood ash, which made it easier to grind into masa and unlocked its niacin. In the north, maize joined beans and squash in the farming system sometimes called the three sisters.

After 1492 maize travelled to Europe, Africa and Asia, where it adapted to many climates and became a staple in places as varied as northern Italy, the Balkans, Mexico, southern Africa and China. Where people relied on maize without nixtamalization, pellagra, a niacin-deficiency disease, appeared in parts of Europe and the American South.

In the twentieth century, hybrid corn and mechanised farming turned maize into the world's highest-volume crop. Today the United States, China, Brazil and Argentina lead production, and most corn is used for animal feed, ethanol fuel and industrial starch and sweeteners, with a smaller share eaten directly. In Africa and Latin America, maize remains a core food staple.

Corn is eaten fresh as corn on the cob, cooked into tortillas, tamales and arepas with masa, boiled into polenta, grits, ugali, sadza and porridge, and popped as popcorn. Cornmeal makes cornbread and breakfast cereals, and cornstarch thickens sauces. The kernels are also fermented into chicha and bourbon, and maize beer is brewed in the Andes and Africa.

Industrial uses include corn syrup, ethanol, bioplastics and livestock feed. Corn oil is pressed from the germ and used for frying. Corn silk is traditionally used in herbal teas.

Whole corn provides starch, fibre, B vitamins, magnesium and carotenoids such as lutein and zeaxanthin, which are found in yellow corn and linked to eye health. Corn is naturally gluten free, making it a mainstay for people with coeliac disease.

Refined corn products like corn syrup, chips and sweetened cereals are different from whole corn, and heavy consumption of such foods is linked to excess calories and sugar. The protein in corn is low in lysine and tryptophan, so diets that rely only on maize need complementary foods such as beans.