Maize

Maize is a tall annual grass, commonly 2 to 3 metres high, with broad leaves and separate male flowers (the tassel) and female flowers that develop into ears. Each ear is wrapped in husks and carries hundreds of kernels in tight rows, usually 12 to 20 rows. Kernels come in yellow, white, red, blue, purple and multicoloured forms. Major types include dent, flint, flour, sweet and popcorn, differing in starch and moisture content. Maize is sold as fresh ears, canned or frozen kernels, dried whole grain, hominy, cornmeal, polenta, masa flour, grits, starch, syrup, oil and popped snacks.

Genetic and archaeological studies indicate that maize was domesticated from a wild grass called teosinte in the Balsas River valley of southern Mexico roughly 9,000 years ago. Early farmers selected plants with larger ears and kernels that stayed on the cob. The English word corn originally meant grain generally, and in North America came to refer to maize specifically. The name maize comes from the Spanish maiz, taken from mahiz, a word of the Taino language of the Caribbean, which Spanish explorers encountered in the late fifteenth century.

From Mexico maize spread across the Americas, reaching the south-western United States, the Andes and eastern North America over the following millennia, becoming the staple of civilisations such as the Maya, Aztec and Inca. It was central to religion and myth, and the Maya believed that people were made from maize dough. Indigenous peoples developed nixtamalisation, soaking the grain in alkaline water, which improves its nutritional quality and flavour and underlies tortillas and tamales.

After 1492 maize was carried to Europe, Africa and Asia, where it was adopted remarkably quickly. It became a staple in southern Europe as polenta, in many parts of Africa as porridge such as ugali, sadza and pap, and in China as a high-yielding crop. In the twentieth century hybrid maize and mechanised farming greatly raised yields, especially in the United States, where the crop became the foundation of livestock feed, sweeteners and ethanol. Today it is grown on every inhabited continent and is among the leading crops by tonnage.

Maize is eaten as fresh sweet corn, popcorn and roasted ears, and ground into flours and meals for tortillas, arepas, polenta, cornbread, porridges, grits and many snack foods. Processed forms include cornstarch, corn syrup, corn oil and breakfast cereals. Fermented and distilled products include chicha and bourbon whiskey. A large proportion of the world crop feeds livestock, and maize is also used for bioethanol and bioplastics. Husks wrap tamales, and silks are used in traditional herbal teas in several cultures.

Whole-grain maize provides starch, fibre and some B vitamins, and yellow and orange varieties contain carotenoids such as lutein and zeaxanthin, which are associated with eye health. Its niacin is poorly absorbed unless the grain has been treated with alkali, which is why diets based on untreated maize have historically been linked to pellagra, a niacin deficiency. Maize protein is low in the amino acids lysine and tryptophan. Whole-grain forms are generally more nutritious than refined meals, and eating a varied diet with legumes balances the protein profile.