For millions of people in the semi-arid tropics of Asia and Africa sorghum and millets are the most important staple foods. These crops sustain the lives of the poorest rural people and will continue to do so in the foreseeable future. Sorghum and millets grow in harsh environments where other crops do not grow well. Improvements in production, availability, storage, utilization and consumption of these food crops will significantly contribute to the household food security and nutrition of the inhabitants of these areas.
Sorghum and millets in human nutrition is a new addition to the FAO Food and Nutrition Series. The publication is broad in scope and coverage, starting with the history and nature of sorghum and millets and dealing with production, utilization and consumption. It provides extensive information on the nutritional value, chemical composition, storage and processing of these foods. In addition, the anti-nutritional factors present in these foods and ways of reducing their health hazards are discussed. The authors have described formulations of various popular foods prepared from sorghum and millets and their nutritional composition and quality, and they have compiled many recipes for the preparation of foods from regions where sorghum and millets are important dietary staples. An extensive bibliography is included as well.
Readers of this book may also be interested in the standards for sorghum and pearl millet grains and flours prepared by the Codex Alimentarius Commission under the Joint FAD/WHO Food Standards Programme.
FAO appreciates the collaboration and assistance of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in the preparation of this book. The Organization acknowledges the contributions of Dr R. Jambunathan and Dr V. Subramanian, both of ICRISAT, to Chapters 1, 2, 3 and 5 as well as those of Dr Y.G. Deosthale, of the National Institute of India, to Chapters 1, 4 and 6 and the Annex.
Sorghum and millets in human nutrition is intended to provide up-to-date scientific and practical information to scientists, government officials, extension workers, university professors and others interested in these foods. It is hoped that this text will assist them in the development of training programmes for their staff and students.
J.R. Lupien
Director
Food and Nutrition Division
1 Codex Alimentarius Commission, 1990. Codex standards for cereals, pulses, legumes and derived products. Supplement 1 to Codex Alimentarius Vol. XVIII. Rome, FAO/WHO. 33 pp
Sorghum and millets have been important staples in the semi-arid tropics of Asia and Africa for centuries. These crops are still the principal sources of energy, protein, vitamins and minerals for millions of the poorest people in these regions.
Sorghum and millets are grown in harsh environments where other crops grow or yield poorly. They are grown with limited water resources and usually without application of any fertilizers or other inputs by a multitude of small-holder farmers in many countries. Therefore, and because they are mostly consumed by disadvantaged groups, they are often referred to as "coarse grain" or "poor people's crops". They are not usually traded in the international markets or even in local markets in many countries. The farmers seldom, therefore, have an assured market in the event of surplus production.
The cereals considered in this publication include sorghum, pearl millet, finger millet, foxtail millet, common millet, little millet, barnyard millet and kodo millet (Table 1). Teff (Eragrostis tef), which is extensively cultivated in Ethiopia, is not strictly a millet and is therefore not included. Other millets such as fonio (Digitaria exilis) and Job's tears (Coix lancryma-jobi) are of minor importance and are not described here.
Sorghum, Sorghum bicolor (L.) Moench, is known under a variety of names: great millet and guinea corn in West Africa, kafir corn in South Africa, dura in Sudan, mtama in eastern Africa, jowar in India and kaoliang in China (Purseglove, 1972). In the United States it is usually referred to as milo or milo-maize (Table 1). Sorghum belongs to the tribe Andropogonae of the grass family Poaceae. Sugar cane, Saceharum officinarum, is a member of this tribe and a close relative of sorghum. The genus Sorghum is characterized by spikelets borne in pairs. Sorghum is treated as an annual, although it is a perennial grass and in the tropics it can be harvested many times.
TABLE 1: Origins and common names of sorghum and millets
| Crop | Common names | Suggested origin |
| Sorghum bicolor | Sorghum, great millet, guinea corn, kafir corn, aura, mtama, jowar, cholam. kaoliang, milo, milo-maize | Northeast quadrant of Africa (Ethiopia-Sudan border) |
| Pennisetum glaucum | Pearl millet, cumbu, spiked millet, bajra, bulrush millet, candle millet, dark millet | Tropical West Africa |
| Eleusine coracana | Finger millet, African millet, koracan, ragi, wimbi, bulo, telebun | Uganda or neighbouring region |
| Setaria italica | Foxtail millet, Italian millet, German millet, Hungarian millet, Siberian millet | Eastern Asia (China) |
| Panicum miliaceum | Proso millet, common millet, hog millet, broom-corn millet, Russian millet, brown corn | Central and eastern Asia |
| Panicum sumatrense | Little millet | Southeast Asia |
| Echinochloa crus-galli | Barnyard millet, sawa millet, Japanese barnyard millet | Japan |
| Paspalum scrobiculatum | Kodo millet | India |
In 1753 Linnaeus described in his Species platarum three species of cultivated sorghum: Holcus sorghum, Holcus saccaratus and Holcus tricolor. In 1794 Moench distinguished the genus Sorghum from the genus Holrcus, and in 1805 Person suggested the name Sorghum vulgare for Holcus sorghum (L.). In 1961 Clayton proposed the name Sorghum bicolor (L.) Moench as the correct name for cultivated sorghum and this is currently being used.
The classification of sorghum by Snowden ( 1936) is detailed and complete. Other classifications proposed since that time have been modifications or adaptations of the Snowden system. Harlan and de Wet (1972) published a simplified classification of sorghum which has been checked against 10 000 head samples. They divided cultivated sorghum into five basic groups or races: bicolor, guinea, caudatum, kafir and durra. The wild type and shatter cane are considered two other spikelet types of S. tricolor. A study of polymorphism of 11 enzymes permitted classification of sorghum into three enzymatic groups. The first includes mainly guinea varieties of West Africa; the second southern African varieties of all five races; and the third durra and caudatum types of Central and East Africa (Ollitrault, Escoute and Noyer, 1989).
The cultivated sorghum of the present arose from a wild progenitor belonging to the subspecies verticilliflorum. The greatest variation in the genus Sorghum is observed in the region of the northeast quadrant of Africa comprising Ethiopia, the Sudan and East Africa (Doggett, 1988 ). It appears that sorghum moved into eastern Africa from Ethiopia around 200 AD or earlier. It was adopted and carried to the savannah countries of eastern and southern Africa by the Bantu people, who used the grain mainly to make beer. The Bantu people probably began their expansion from the region of southern Cameroon about the first century AD, moved along the southern border of the Congo forest belt and reached eastern Africa possibly before 500 AD. The present-day sorghums of central and southern Africa are closely related to those of the United Republic of Tanzania and more distantly related to those of West Africa, as the equatorial forests were an effective barrier to this spread.
Sorghum was probably taken to India from eastern Africa during the first millennium BC. It is reported to have existed there around 1000 BC. Sorghum was probably taken in ships as food in the first instance; chow traffic has operated for some 3 000 years between East Africa (the Azanean Coast) and India via the Sebaean Lane in southern Arabia. The sorghums of India are related to those of northeastern Africa and the coast between Cape Guardafui and Mozambique.
The spread along the coast of Southeast Asia and around China may have taken place about the beginning of the Christian era, but it is also possible that sorghum arrived much earlier in China via the silk trade routes.
Grain sorghum appears to have arrived in America as "guinea corn" from West Africa with the slave traders about the middle of the nineteenth century. Although sorghum arrived in Latin America through the slave trade and by navigators plying the Europe-Africa-Latin America trade route in the sixteenth century, the crop did not become important until the present century. The case is similar for Australia.
Grain sorghum grown primarily for food uses can be divided into milo, kafir, hegari, feterita and hybrids (Purseglove, 1972). There are other classes of sorghums such as sorghos, grass sorghums, broom-corn sorghum and specialpurpose sorghum.
The sorghum kernel varies in colour from white through shades of red and brown to pale yellow to deep purple-brown. The most common colours are white, bronze and brown. Kernels are generally spherical but vary in size and shape. The caryopsis can be rounded and bluntly pointed, 4 to 8 mm in diameter (Purseglove, 1972). The I 000-kernel weight has a very wide range of values, from 3 to 80 g, but in the majority of varieties it is between 25 and 30 g. The grain is partially covered with glumes. Large grains with corneous endosperm are usually preferred for human consumption. Yellow endosperm with carotene and xanthophyll increases the nutritive value. Sorghum grain that has a testa contains tannin in varying proportions depending on the variety.
Pearl millet, Pennisetum glaucum, is also known as spiked millet, bajra (in India) and bulrush millet (Purseglove, 1972). Pearl millet may be considered as a single species but it includes a number of cultivated races. It almost certainly originated in tropical western Africa, where the greatest number of both wild and cultivated forms occurs. About 2 000 years ago the crop was carried to eastern and central Africa and to India, where because of its excellent tolerance to drought it became established in the drier environments.
The height of the pearl millet plant may range from 0.5 to 4 m and the grain can be nearly white, pale yellow, brown, grey, slate blue or purple. The ovoid grains are about 3 to 4 mm long, much larger than those of other millets, and the 1 000-seed weight ranges from 2.5 to 14 g with a mean of 8 g. The size of the pearl millet kernel is about one-third that of sorghum. The relative proportion of germ to endosperm is higher than in sorghum.
Minor millets (also referred to as small millets) (Seetharam, Riley and Harinarayana, 1989) have received far less attention than sorghum in terms of cultivation and utilization. They include finger millet (Eleusine coracana), foxtail millet (Setaria italica), kodo millet (Paspalum scrobiculatum), common or prove millet (Panicum miliaceum), little millet (Panicum sumatrense) and barnyard or sawa millet (Echinochloa crus-galli and Echinochloa corona) (Table 1). More information is available on finger millet than on any of the others. Minor millets account for less than one percent of the foodgrains produced in the world today. Thus they are not important in terms of world food production, but they are essential as food crops in their respective agro-ecosystems. They are mostly grown in marginal areas or under agricultural conditions where major cereals fail to give sustainable yields. Detailed descriptions of these millets are given by Purseglove ( 1972).
Finger millet
Finger millet, Eleusine coracana L., is also known as African millet, koracan, ragi (India), wimbi (Swahili), bulo (Uganda) and telebun (the Sudan). It is an important staple food in parts of eastern and central Africa and India. It is the principal cereal grain in northern and parts of western Uganda and northeastern Zambia. The grains are malted for making beer. Finger millet can be stored for long periods without insect damage (Purseglove, 1972) and thus it can be important during famine. Numerous cultivars have been identified. In India and Africa, two groups are recognized: African highland types with grains enclosed within the florets; and Afro-Asiatic types with mature grains exposed outside the florets. It is believed that Uganda or a neighbouring region is the centre of origin of E. coracana, and it was introduced to India at a very early date, probably over 3 000 years ago. Though finger millet is reported to have reached Europe at about the commencement of the Christian era, its utilization is restricted mostly to eastern Africa and India.
The height of cultivars varies from 40 cm to I m and the spike length ranges from 3 to 13 cm. The colour of grains may vary from white through orange-red deep brown and purple, to almost black. The grains are smaller than those of pearl millet, and the mean I 000-seed weight is about 2.6 g.
Foxtail millet
Foxtail millet, Setaria italica L., is also known as Italian, German Hungarian or Siberian millet. It is generally considered to have been domesticated in eastern Asia, where it has been cultivated since ancient times. The main production area is China, but S. italic a is the most important millet in Japan and is widely cultivated in India (Purseglove, 1972). It is believed to have been one of the five sacred plants of ancient China (from 2700 BC). Because of its short duration it is a suitable crop for growing by nomads, and it was probably brought to Europe in this way during the Stone Age, as seeds abound in the Lake Dwellings in Europe.
The height of the plants varies from 1 to 1.5 m and the colour of the grain varies from pale yellow, through orange, red and brown to black. The 1 000-seed weight is about 2 g.
Common millet
Common millet, Panicum miliaceum L., is also known as prove millet, hog millet, broom-corn millet, Russian millet and brown corn. This millet is of ancient cultivation. It is the milium of the Romans and the true millet of history. It was cultivated by the early Lake Dwellers in Europe. It is believed to have been domesticated in central and eastern Asia and because of its ability to mature quickly was often grown by nomads.
The shallow-rooted plant varies in height between 30 and 100 cm. The grain contains a comparatively high percentage of indigestible fibre because the seeds are enclosed in the hulls and are difficult to remove by conventional milling processes. The 1 000-seed weight is about 5 g (varying between 4.7 and 7.2 g). Common millet is particularly suited to dry continental conditions and grows in more temperate climates than other millets.
Little millet
Little millet, Panicum sumatrense Roth ex Roemer & Schultes, is grown throughout India to a limited extent up to altitudes of 2 100 m but is of little importance elsewhere. It has received comparatively little attention from plant breeders. The plant varies in height between 30 and 90 cm and its oblong panicle varies in length between 14 and 40 cm. The seeds of little millet are smaller than those of common millet.
Barnyard millet
Barnyard, Japanese barnyard or sawa millet [Echinochloa crus-galli (L.) P.B. and Echinochloa colona (L.) Link] is the fastest growing of all millets and produces a crop in six weeks. It is grown in India, Japan and China as a substitute for rice when the paddy fails. It is grown as a forage crop in the United States and can produce as many as eight harvests per year. The plant has attracted some attention as a fodder in the United States and Japan. The height of the plant varies between 50 and 100 cm.
Kodo millet
Kodo millet, Paspalum scrobiculatum L., is a minor grain crop in India but is of great importance in the Deccan Plateau. Its cultivation in India is generally confined to Gujarat, Karnataka and parts of Tamil Nadu. It is classified into the groups Haria, Choudharia, Kodra and Haria-Choudharia depending on panicle characters. Kodo is an annual tufted grass that grows to 90 cm high. Some forms have been reported to be poisonous to humans and animals, possibly because of a fungus infecting the grain. The grain is enclosed in hard, corneous, persistent husks that are difficult to remove. The grain may vary in colour from light red to dark grey.