National Academies Press: OpenBook
« Previous: Malnutrition and Protein Quality
Suggested Citation:"Maize." National Research Council. 1988. Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co. Washington, DC: The National Academies Press. doi: 10.17226/18563.
×
Page 8
Suggested Citation:"Maize." National Research Council. 1988. Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co. Washington, DC: The National Academies Press. doi: 10.17226/18563.
×
Page 9
Suggested Citation:"Maize." National Research Council. 1988. Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co. Washington, DC: The National Academies Press. doi: 10.17226/18563.
×
Page 10
Suggested Citation:"Maize." National Research Council. 1988. Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co. Washington, DC: The National Academies Press. doi: 10.17226/18563.
×
Page 11
Suggested Citation:"Maize." National Research Council. 1988. Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co. Washington, DC: The National Academies Press. doi: 10.17226/18563.
×
Page 12
Suggested Citation:"Maize." National Research Council. 1988. Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co. Washington, DC: The National Academies Press. doi: 10.17226/18563.
×
Page 13
Suggested Citation:"Maize." National Research Council. 1988. Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co. Washington, DC: The National Academies Press. doi: 10.17226/18563.
×
Page 14
Suggested Citation:"Maize." National Research Council. 1988. Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co. Washington, DC: The National Academies Press. doi: 10.17226/18563.
×
Page 15
Suggested Citation:"Maize." National Research Council. 1988. Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co. Washington, DC: The National Academies Press. doi: 10.17226/18563.
×
Page 16
Suggested Citation:"Maize." National Research Council. 1988. Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co. Washington, DC: The National Academies Press. doi: 10.17226/18563.
×
Page 17

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

2 Maize Maize was the principal food of the ancient civilizations of the Western Hemisphere: the Incas of Peru, the Mayas of Central America, the Aztecs of Mexico, and the many tribes of eastern North America. In the pre-Columbian New World it was the most important cultivated crop, depended on by peoples over a vast area from southern Chile to southern Canada and at altitudes from sea level to 3,300 m. Before November 5,1492, the plant was known only to the inhabitants of the Americas. But on that day two of Christopher Columbus's crew, returning from a trip to the interior of Cuba, presented their leader with "a sort of grain" they said the Caribs called maize. The Admiral transported the intriguing seed back to Spain as one of the wonders of the New World. In this way, maize left its ancestral home and, within a comparatively short time, became an important source of food in scores of tropical, subtropical, and warm-temperate countries. Today, maize is one of the handful of plants that can be said to support the world's food supply. In area planted, it ranks as the second or third major crop. In 1985, according to the Food and Agriculture Organization of the United Nations (FAO), it was grown on 133 million hectares. It is grown from latitude 40°S in Argentina to latitude 58°N in Canada and the Soviet Union. And it is grown at all longitudes: somewhere in the world a maize crop matures every month of the year (see map, pp. 10-11). Maize now supports a worldwide business worth $40 billion annually. Moreover, it is rapidly becoming more popular: annual world produc- tion almost tripled between 1930 and 1980, and it increased a remarkable 14 percent—from 395 million to 449 million tons1—between 1980 and 1985. Most of the crop is used in the country in which it is grown; only about 10 percent enters international trade, yet even this small fraction provides more than two-thirds of the total international trade in feed grains. 1 Throughout this report, all amounts in tons refer to metric tons. 8

MAIZE 9 The maize crop is now so large that its annual production represents about 90 kg of grain for every person on earth. Averaging 9.5 percent protein, it contributes some 42 million tons of protein a year, which represents 15 percent of the world's annual production of food-crop protein (figure 2.1). It also represents 19 percent of the world's food calories. MAIZE AND THE THIRD WORLD In many areas of the developing world, maize is a vital staple, particularly for the rural poor. It spread quickly and widely among poor countries because it was robust and highly adaptable to a wide range of environments and because of its many valuable properties. For example, maize: • Gives one of the highest yields per hour of labor spent; • Provides nutrients in a compact form; • Is easily transportable; • Is protected against birds and rain by its husks; Wheat Rye |j:| Sweet Potato 10 15 20 PERCENT OF WORLD CROP PROTEIN 25 30 FIGURE 2.1 Maize contributes 15.4 percent of the protein produced by the world's crops—more than any other plant except wheat.

10 QUALITY-PROTEIN MAIZE Maize is the most widely distributed crop and the most important cereal in the world after wheat and rice. Is easy to harvest and can be shelled by hand; Stores well if properly dried; Is relatively free of major disease epidemics; Competes with weeds better than other cereals; Does not shatter and thus can be left standing in the field at maturity; and • Has cultivars with different maturing periods. Moreover, maize is one of the most versatile of all agricultural

MAIZE 11 products, being employed as human food, livestock feed, and raw ingredient for hundreds of industrial materials. Because of all these benefits, maize became a favorite crop with farmers in scores of developing countries. It is the staple of at least 200 million people in Brazil, El Salvador, Ecuador, Guatemala, Haiti, Honduras, Mexico, Nicaragua, Paraguay, Venezuela, Benin, Ghana, Kenya, Malawi, Nigeria, South Africa, Tanzania, Zaire, Zambia, and Zimbabwe. Maize is also an important food crop in the Mediterranean region, the Middle East, and parts of Asia.

12 QUALITY-PROTEIN MAIZE Maize in Latin America As in ancient times, maize is still the major grain of most of the Americas. Today, farmers in Latin America and the Caribbean plant some 10.2 million hectares of it each year. For much of the populace, maize constitutes the main bulk of the daily diet. For instance, it makes up 85 percent of all cereals consumed in Mexico and Central America. It provides 65 percent of all the calories in the diets of families in Guatemala, 62 percent of those in El Salvador, and 49 percent of those in Honduras.2 A typical daily diet of campesinos in these countries is 500 g of maize for men, 350 g for women, and 150 g for children.3 In Mexico, Guatemala, and Honduras, the per capita consumption of maize is about 100 kg per year, and for the most destitute people the intake is even higher. The maize tortilla is the basic food for the majority of the people, particularly the poor. Maize in Africa Since the 1400s, when the Portuguese began trading along the West African coast, Europeans have introduced several American food crops to Africa. Those that have become established include cassava, peanuts, sweet potatoes, beans, and maize. Of these, maize was the most rapidly adopted. Where rainfall was adequate, it could give two harvests a year, and the method of planting it in mounds was familiar to West Africans who had traditionally grown yams this way. By the 1600s, maize was a major crop in the sub-Guinean zone and in the Congo basin. In the 1700s, it spread rapidly in the Gold Coast. In the 1800s, it was adopted in eastern and southern Africa. Now— particularly in South Africa, Malawi, Zambia, Zimbabwe, and Kenya, as well as in large areas of Ghana, Nigeria, Ethiopia, and Egypt—it is a major cereal crop. Indeed, for the African continent as a whole, maize is probably the leading cereal. In many African countries, maize is the basic food for subsistence farmers, miners, and city dwellers. In most areas, its importance is as great as that of wheat in the Mideast and rice in Southeast Asia. In fact, Africans consume nearly one-fourth of the world's total food maize.4 In Kenya, Malawi, Zambia, and Zimbabwe, per capita con- sumption is about 100 kg per year. In Tanzania, Mozambique, Benin, Togo, Cameroon, and Egypt, per capita consumption is about 40 kg per year. 2INCAP, 1969. 3 Information from R. Bressani. 4 Byerlee and Winkelmann, 1981.

MAIZE 13 Maize in Asia In most of Southeast Asia, where conditions are suited to paddy rice, maize has never been more than a secondary cereal. But where climates are too dry for paddy rice, it has become important—for instance, in parts of Pakistan, India, China, Indochina, the Philippines, and Indonesia. Today, maize is second only to rice in most Asian countries. In Nepal and the Philippines, for example, the per capita maize consumption is about 40 kg per year. MAIZE AS FOOD Maize is extremely adaptable and is prepared and consumed in a multitude of ways. In the main, however, it is ground and pounded, and the resulting maize meal is boiled, baked, or fried. In Latin America, maize is steeped with lime (or ash), boiled, and ground into a fine dough (masa). Tortillas—an unleavened pancakelike cornbread—are made by baking thin flat cakes of masa until they are crisp. Tamales are produced by steaming the masa. Cornbread is made from maize meal, either alone or mixed with wheat flour. A gruel, often flavored with honey or peppers, is also consumed. In Africa, the most common method of eating maize is to boil the meal with water until it forms a thick mush or dough. It is also often cooked in more diluted forms to provide porridge, gruel, soup, and even beer. MAIZE AND MALNUTRITION As noted, about half of the world's chronically undernourished people live in countries where maize is a staple (figure 2.2). In Central America, for instance, poverty-stricken adults commonly consume only maize. A typical diet consists of 20 or more tortillas a day, supplemented with hot peppers, some native greens, and little or nothing more (table 2.1). Many children of the poor also eat few nutritious solid foods, and when they do, the amounts are small.5 5 For example, a 3-year-long analysis in the poorest town in Guatemala showed that during their first year of life only a few children got any of the most nutritious foods. Moreover, when they did get nutritious foods, the amounts being ingested were very small. Out of 45 8-month-old children, only 2 consumed cow's milk (averaging 32 g each per day), only 2 consumed eggs (less than 1 g each), and none got meat or beans. By the time they were 11 months old, only 1 was drinking cow's milk, 16 were getting eggs (merely 5 g), 24 were getting meat (averaging less than 1 g), and 2 were consuming beans (also less than 1 g). (Garcia and Urrutia, 1978.)

14 QUALITY-PROTEIN MAIZE Figures Represent ihe Annual Number of Child Deaths (0-4 yean) I (in thousands) Mall (118)"" Malawi (97) Guinea (65) Kampuchea (75) Ethiopia (440) Mozamblque(151) Central African Republic (26) Chad (51) Guinea-Bissau (8) Haiti (48) Liberia (22) Rwanda (64) Bolivia (52) Burundi (43) Benin (38) Laos (30) Nigeria (846) Tanzania (200) India (4028) Ivory Coast (68) Lesotho (9) Uganda (134) Zaire (24) Cameroon (67) Peru (97) Togo (21) Ghana (94) Turkey(177) Zambia (42) f Indonesia (655) South Africa (132) Congo (9) Honduras (22) Kenya(132) Zimbabwe (49) Botswana (5) Dominican Republic (18) Nicaragua (15) Brazil (377) Ecuador(34) El Salvador (20) Guatemala (36) Madagascar (43) Mexico (193) Colombia (63) Philippines (138) Thailand (86) Paraguay (8) China (1041) Venezuela (28) Argentina (31) Guyana (1) Yugoslavia (13) Uruguay (2) Romania (13) Panama (2) Very High IMR (over 100) High IMR 155-100) Middle IMR (25-50) 7 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 INFANT MORTALITY RATE (IMR) (UNDER 1 YEAR) IN DEATHS PER 1,000 LIVE BIRTHS FIGURE 2.2 The infant mortality in some maize-growing countries is extremely high. Collectively, these countries account for more than 10 million deaths a year due to malnutrition. (UNICEF, 1985. [Figures are for 1983.])

MAIZE 15 This is of concern because maize is low in protein quantity and protein quality, both of which are insufficient to satisfy the protein needs of the special groups that are most vulnerable to malnutrition. The prevalence of protein-calorie malnutrition among village and slum children in dozens of African and Latin American countries demon- strates the underlying inadequacy of maize-dependent diets. As noted, maize kernels contain, on average, only about 9.5 percent protein—a low figure compared with legume seeds such as beans (23 percent), peanuts (26 percent), or soybeans (38 percent). But an even more serious limitation is maize protein's low levels of two nutritionally vital amino acids, lysine and tryptophan. Both are essential amino acids that people (and other simple-stomach animals such as pigs and poultry) must obtain from food because they cannot synthesize them for themselves. Roughly half of the protein in a kernel of common maize is composed of protein types that contain almost no lysine or tryptophan. Maize is deficient in an important vitamin as well. It is low in available niacin, and bodies deficient in this B-vitamin develop pellagra. First described after maize was introduced to Europe, pellagra (char- acterized by dermatitis, diarrhea, and dementia) spread widely through- out most of the maize-dependent regions of the world. (It is also found in sorghum-dependent populations in southern Africa, East Africa, Sudan, India, and elsewhere because sorghum, too, lacks biologically available niacin.) TABLE 2.1 Average Daily Food Consumption (in grams) for Three Population Groups in Santa Maria Cauque, Guatemala 1964-1972." Weaned children at Women in third Mothers in third Type of food 3 years of age trimester of pregnancy trimester of lactation Tortillas (maize) 226 595 666 Vegetables 41 53 35 Sugars 29 83 58 Beans 27 56 43 Bananas 17 7 2 Fruits 14 15 24 Breads 14 30 21 Rice & pasta 7 9 8 Eggs 8 7 8 Meat 6 21 15 Cow's milk 2 0 0 Fresh cheese 0 2 2 Coffee 2 5 5 Fats/oil 0 1 3 • This analysis of the food intake of three population groups during a period of six years shows the huge dependence on maize as a basic food as well as the low intake of food products from animal origin. Maize is the cheapest cereal in the area, is produced locally, and contributes 47 percent of the calories of the diets of preschool children and around 60 percent of those of pregnant and lactating mothers. SOURCE: Garcia and Urrutia, 1978.

16 QUALITY-PROTEIN MAIZE MAIZE AND PELLAGRA Since maize is deficient in lysine, tryptophan, and niacin, how did the American Indians escape pellagra when maize was their principal food for thousands of years? The answer is that throughout much of the Americas the Indians prepared their maize using lime. For example, tortillas are prepared by cooking the dried kernels in a weak solution of lime water (made from wood ash, shells, or other sources) for at least half an hour before they are ground to yield the dough. Modern research has shown that this frees up the small amount of niacin that is otherwise unavailable to humans. Liming also supplies calcium, an essential mineral. Indians were undoubtedly unaware that their method for preparing maize increased its nutritional value; the procedure was probably adopted because they found that the hard kernels were softened by the lime water and could be ground more easily. However it happened, it was a happy discovery. Although still occurring where diets are unduly dependent upon maize, the acute form of pellagra has vanished from most of its former range. Since World War II it has been found only occasionally. Nonetheless, chronic pellagra, even at a low level, is a threat; any disruption in food supply can cause it once again to become a scourge. Forced migrations, crop failures, import restrictions, civil disturbances, wars (of which there were 40 in 1986), and natural calamities all can reduce the availability of dietary ingredients that now (barely) keep the disease suppressed. Such disruptions force people back on a subsistence diet, and where maize or sorghum are staples, pellagra will emerge once more.6 MAIZE AS FEED During its worldwide dispersal, maize became the world's chief animal feed. Today it provides more feed than any other grain. For this purpose, it is outstanding: high in energy, low in fiber, and easily digested by most livestock species. Industrialized countries, such as the United States, use their maize crop mainly as feed and depend on it to produce their meat, milk, and eggs. (If one includes these animal products along with direct consumption by people, maize actually provides the United States with more food than any other crop.) 6 For a review, see Stratigos and Katsambas, 1977. One major cause of present-day pellagra is alcoholism.

MAIZE 17 The grain is fed mostly to pigs, cattle, and poultry, but also to sheep. The plant's stems and leaves are also an important forage, and are fed green, dried, or ensiled. In developing nations—where, by the year 2000, some 60 percent of the world population is projected to live (or hope to get enough food to live)—no more than 3 percent of available cereal grains goes into animal feed. But this is beginning to change, and the amount of grains that developing countries divert to animals is expected to increase to much higher levels in coming decades.

Next: Nutritionally Improved Maize »
Quality-Protein Maize: Report of an Ad Hoc Panel of the Advisory Committee on Technology Innovation Board on Science and Technology for International Development National Research Council, in Cooperation With the Board on Agriculture National Research Co Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF
  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!