Open access peer-reviewed chapter

Millets Cereal Grains: Nutritional Composition and Utilisation in Sub-Saharan Africa

By Shonisani Eugenia Ramashia, Mpho E. Mashau and Oluwatoyin O. Onipe

Submitted: February 2nd 2021Reviewed: March 16th 2021Published: December 6th 2021

DOI: 10.5772/intechopen.97272

Downloaded: 55

Abstract

Millets are small to medium size cereal grain crops that are cultivated throughout the tropics and subtropical region. The grains are used for food and fodder for feeding animals around the globe. Millets have great economic, health importance, gluten-free, have low glycemic index and are known as “nutra–cereals”. The grains are mostly utilised as a food source by population with lower socio-economic factors which are traditional consumers in the farm and village levels. They are rich sources of carbohydrates, protein, crude fibre, phytochemicals, minerals, and vitamins. They are processed by using different traditional processes such as soaking, germination, malting, fermentation, milling or grinding, cooking, roasting and popping. Millet grains/ flours are utilised and consumed as flat breads, biscuits, snacks, beverages, porridges, chapati, dosa, pastas. There is a need to produce new value-added products from millets which is underutilised crop to improve food security and prevent micronutrients deficiencies.

Keywords

  • Millets
  • cereal grains
  • nutritional composition
  • health benefits
  • utilisation

1. Introduction

Millets are cereal crops that belong to the family Gramineaeand they are small-seeded species [1, 2, 3]. Most millets belong to the tribe Panicoideaeapart from finger millet and teff that belong to the tribe Eragrostideae[4, 5, 6]. The grains are available in some parts of African countries and they are cheap [7]. They differ from each other by their appearance, grains quality, taste, morphological and biochemical behavior [8]. They are widely grown around the world for food and fodder and are staple food in the West, East, Central and Great Lakes region of Africa as well as in Asia and India [9, 10, 11]. The word millet has been derived from the French word “mille” which means thousand, a handful of millet has been referred to contain thousands of grains [12]. Millets are classified with maize and sorghum in the grass sub-family Panicoideae[3, 8]. They are the 6th most important cereal grain crop in the world agricultural production after wheat, maize, sorghum, rice, and barley that are regarded as the major economic grains in the world [13, 14, 15]. Millets are resistant to pests and diseases as compared to other cereal grains [1, 13]. They are major food sources for millions of people, especially those who live in hot, dry areas of the world, adapt to harsh environment especially drought conditions. Millets are one of the cereal grain crops that are drought-tolerant and have short growing season [15, 16]. They grow well on poorly fertilised and dry soils with short rainfall periods [1, 17]. The grains are cultivated between February and August while harvested in June or January [18]. About 55–60% of worldwide produced millet grains are cultivated in the sub-Saharan Africa including Ethiopia, Kenya, Malawi, Nigeria, Tanzania, Uganda, Zambia, and Zimbabwe (Table 1). Major types of cultivated millet species varieties are finger millet (Eleusine coracana), pearl millet (Pennisetum glaucum), Japanese banyard millet (Ecchinochloa frumentacea); foxtail millet (Setaria italica)and proso or white millet (Panicum miliaceum)[20, 21].

CountriesYearly production (in tonnes)
20152016201720182019
Angola4374642000700006985451054
Benin2164025182247172614325000
Botswana555126410992462902
Burkina Faso9461849050718282341189079970176
Burundi997010019995598919827
Cameroon9581099015101101103186105271
Central African Republic1000010000100001000010000
Chad592124725677660175756616717621
Congo1319713595138961419714499
Côte d’Ivoire5520058300616006500065000
Democratic Republic of the Congo4377641006408874090840930
Ethiopia10364441017059103082310356301125958
Gambia7342065073520003800035000
Ghana157369159017163484181564190000
Guinea224587238177241714214747223220
Guinea-Bissau1400014000161771800020000
Kenya99000540005400072000135000
Malawi3351219510351213131534479
Mali18643011806559149265018403211878527
Mauritania27903145327732473218
Morocco49534564431241043928
Mozambique1091621000210001986912832
Namibia4249419428576448351518700
Niger34048133886079379002838563443270453
Nigeria14853871552576150000021190002000000
Rwanda49605021508351405195
Senegal749874493340875484897574807044
Sierra Leone4400038000390003800038000
South Africa62435950568354245160
South Sudan80006000500050005000
Sudan486000144900087800026470001133000
Togo3866423838260442608226806
Uganda236484193461211050238558243104
Zambia3196729972325663227824843
Zimbabwe1767227461621573896435000

Table 1.

Millet production in sub Saharan Africa in thousands per tons from 2015 to 2019.

Source: [19].

The millet grains are gluten-free, non-acid forming, easy to digest, low glycemic index and healthy food diet for people with celiac disease – common disease caused by cereal protein ingestion [1, 2, 19, 22]. Other gluten-free cereal grains are maize, brown rice and sorghum while barley, wheat and rye are gluten rich cereal grains [4]. Table 2 and Figure 1 show the major cultivated millet species in the world. Millets are globally grown in different regions from East to West and they are called in different names around the globe which indicate their specific originality such as foxtail millet as Italian millet, proso as French millet and barnyard as Japanese millet [25]. Finger millet originated in East Africa while white fonio (Digitaria exilis), black fonio (Digitaria iburua) and pearl millet originated in West Africa [26]. Table 3 shows various characteristics of millet species and their functions are shown in Table 4.

Common nameTribes/genus and speciesReferences
Finger millet/ragi/mandua/nagli/nachani/kurakkan/mufhohoEleusine coracana[2, 20]
TeffEragrostis tef[4]
White fonio (acha)Digitaria exilis[22, 23]
Black fonio (iburu)Digitaria iburua
Barnyard millet/banti/kudiraivali sawan/shamaEchinochloa frumentacea[1, 2, 24]
Proso millet/panivaragu/kutki/cheenaPanicum miliaceum[13, 20]
Kodo millet/haraka/varagu/kodra/ditchPaspalum scrobiculatum[13, 15]
Foxtail millet/navane/tenia/kauni/kakunSetaria italic[2, 13]
Pearl millet/bajra/cambu/saije/cattailPennisetum glaucum[15, 20]

Table 2.

Major cultivated millet species.

Figure 1.

Cultivated millet species. A = Foxtail millet; B = Pearl millet; C = Proso millet; D = Banyard millet; E = Teff millet and F = Kodo millet. Source: [25].

MilletColourShapeSizeOrigin
Foxtail milletPale yellow to redOvoid2 mm longChina
Finger milletLight to dark brownSpherical1–2 mm in diameterEast Central Africa (Uganda)
Proso milletWhite cream, yellow, orangeSpherical oval3 mm long/ 2 mm diameterCentral and eastern Asia
Pearl milletWhite, grey, pale yellow, brown, or purple.Ovoid3–4 mm in lengthTropical West Africa (Sahel)
Kodo milletBlackish to dark brownElliptical and oval1.2 to 9.5 μm longMainly in India also in west Africa
Little milletGrey to straw whiteElliptical and oval1.8 to 1.9 mm longSoutheast Asia
Banyard milletWhiteTiny round2–3 mm longMainly Japan and India

Table 3.

Various characteristics of millet species.

Source: [18].

MilletFunctions
Finger milletIt prevents tissue damage and stimulates the wound healing process in diabetic rats. Prevents cardiovascular disease by reducing plasma triglycerides in hyperlipidemic rats.
Proso milletGluten-free and can prevent humans from celiac disease. Helpful in reducing the risk of type 2 diabetes in humans due to a low glycemic index.
Foxtail milletIt prevents colorectal cancer in mice models. Reduces cholesterol level & have an antidiabetic effect on impaired glucose tolerance persons. Capable of attenuating acute ethanol-induced hepatic injury in mice.
Pearl milletPrevention of celiac disease in humans due to gluten-free property. Stimulates the immune system to prevent the Shigella-induced pathogenicity in the mice model.
Banyard milletActs as an inhibitor of cancer by inducing apoptotic cell death in HT-29 human colon cancer cell line. Its phenolic content inhibits the protein glycation and glycoxidation, which plays a crucial role in the progression of diabetes.
Little milletPrevents from modern metabolic disorders due to the presence of polyphenols.
Kodo milletReduce glycemic index and prevents diabetes in the human female model, also have antioxidant activities.

Table 4.

Functions of millet species.

Source: [25].

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2. Nutritional composition of millet species

Some nutritional values of millets are similar to that of wheat and rice. Millets are staple food for many African countries; however, they are low in macro nutrients such as protein and fat but rich in vitamins and minerals [7]. Millets are a good source of magnesium which reduces the severity of asthma, frequency of migraines, lowers high blood pressure and reduces the risk of heart attacks. These nutrients play important roles in human nutrition [27]. The grains are also a good source of diet for growing children and expectant mothers [28]. They are a good source of phytochemicals such as polyphenols, tannins, and phytic acid which helps to lower cholesterol and reduces cancer risk, high blood pressure, heart disease and diabetes [21, 27]. Other potential health benefits and medical function of millets are increasing in time span of gastric emptying and provides roughage to gastro intestine. Millet is also known as an alkaline forming food. Alkaline based diet is often recommended to get better optimal health and prevent illness/ diseases [7, 29].

Table 5 shows the nutritional composition of some millet’s species. They have higher amount of minerals such as magnesium, manganese, phosphorus, iron, copper, and potassium when compared with corn, sorghum, and wheat [1, 8, 30]. The main nutrients in millets are starch, protein, lipid, dietary fibre, vitamins, and minerals as shown in Table 6. When comparing millet with other cereals, millet contains 75% of carbohydrates and is low in fat (2–5%) content than maize, rice, and sorghum [1, 2, 8]. Other potential health benefits of millets are the development and repair of body tissue, the prevention of gallstones, protection against breast cancer and protection against postmenopausal complications and the reduction of chances of childhood cancer [1, 2]. Millets contain 65–75% of complex carbohydrates, 5.6–12% protein, fat, 2–5%, 15–20% crude fibre and 2.5–3.5% minerals.

Mineral contents (mg/ kg)MilletWheatMaizeRiceSorghum
Phosphorus240011709901030350
Potassium2200155012001500240
Magnesium1000250470350188
Calcium100170606027
SodiumNone2010205
Zinc3485173
Iron4812111211
Manganese75NA91
Source: [30]
Nutrient compositions (g/100 g)
Protein7–1211.6–11.88.1–10.56.8–77.9
Fat2–51.5–2.03.8–4.60.5–12.8
Minerals1.0–2.31.5–1.81.20.61.6
Dietary fibre15–202.0–12.62.8–13.44.12.3–12.8
Carbohydrates65–7571.0–71.273.078.2–79.073.0
Vitamins (mg/100 g)
Riboflavin0.250.170.200.060.15
Thiamine0.590.450.380.060.38
Niacin3.25.53.61.94.3

Table 5.

Nutritional composition of whole grains (at 12% moisture).

NA – not applicable.

Sources: [1, 14, 27, 30, 31, 32].

ContentsFoxtail milletKodo milletBarnyard milletPearl millet
Proximate composition (g)
Moisture11.212.811.912.4
Protein11.50–12.39.86.211.6–11.8
Fat2.38–4.31.32.24.8–5.0
Minerals0.47–3.32.64.42.2–2.3
Dietary fiber2.5–8.52.471.9811.3
Carbohydrates60.9–75.265.9–66.665.567–67.5
Energy (kcal)331309307361–363
Minerals (mg)
Phosphorus290188280296
Potassium250144307
Magnesium81147–22882137
Calcium312720–2242
Sodium4.64.610.9
Zinc2.40.73.03.1
Iron2.80.5–5.05.0–18.68.0
Manganese0.601.10–3.30.961.15
Copper2.41.600.601.06

Table 6.

Proximate composition and mineral contents of some millet species.

Sources: [1, 13, 31].

Millets are rich source of antioxidant activity such as phenolic compounds that contains phenolic acids, flavonoids, and tannins. Phenolic acids are sub-divided into hydroxybenzoic acids, hydroxycinnamic acids, hydroxyphenylacetic acids and hydroxyphenylpropanoic acids (Table 7). The phenolic compounds of millets phenols are reported to have antioxidant, anti-mutagenic, anti-oestrogenic, anti-inflammatory, antiviral effects, and platelet aggregation inhibitory activity [18]. The antioxidant activities of foxtail and proso millets are high because of their high total carotenoid and tocopherol content which range from 78 to 366 and 1.3–4.0 mg/100 g. The grain has good nutritional value however it is mostly consumed by traditional consumers in a tribal community. Its products are scarce in the urban areas as compared to rice ready-to-eat products [7, 29]. The major challenge with millet grains is that the commercial industrial method of processing the grains are not well-known or developed as compared to other cereal grains [29].

Phenolic compoundFoxtail milletKodo milletBarnyard milletPearl millet
Hydroxybenzoic acid and derivatives
Methyl vanillate19.8
Protocatechuic acid10.239.711.8
p-Hydroxybenzoic acid5.6310.522
Vanillic22.14.0116.3, 7.08
Syringic93.117.3
Gentisic acid21.596.3
Hydroxycinnamic acid and derivatives
Caffeic acid3427621.3
p-Coumaric acid848767268.9
Trans-ferulic acid6311844637
Cis-ferulic acid10110081.5
8,8′-Aryl ferulic acid19.694.8
5,5′-Di ferulic acid62.217357
Flavonoids16917371

Table 7.

Phenolic compound content (μg/g defatted meal) of some millet species.

Source: [27].

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3. Processing and utilisation of millet grains/flours

Processing is a technology which is used to convert the cereal grains into an edible form of food products. Millet grains are prepared using modern and traditional technologies such as soaking, germination, malting, fermentation, milling or grinding, cooking, roasting, compositing flour, fortification, irradiation and popping or puffing mostly widely used in rural areas [13, 33, 34]. Traditionally, millet grains are spread and dried in the sun for a period of one week and are stored inside the bags for future use or processing. The grains can be stored for 5 to 10 years. These processes improve the consumption, nutritional composition, and sensory attributes of food products. Various studies has been conducted and the researchers have tried to produced millets products like puffed, popped, flaked, extruded and roller dried products; fermented, malted and composite flours; weaning foods. Some of the recent studies are promising to produce popped and milled products [7]. Current and emerging food products produced from millet grains/ flours are shown in Tables 8 and 9.

CurrentEmerging
Foods
  • Flours and meals (Africa and India)

  • Dumplings, porridges, and gruels (Africa and India)

  • Rice (Africa and India)

  • Couscous (Africa)

  • Malt (Africa and India)

Foods
  • Gluten-free baked products (USA)

  • Ready-to-eat breakfast cereals (USA)

  • Noodles (Japan)

  • Instant porridges (Africa)

  • Instant infant foods (South Africa)

  • Expanded snack foods (Africa)

Beverages
  • Non-alcoholic fermented beverages (Africa, Europe, and Asia)

  • Cloudy opaque beers (Africa and Asia)

  • Spirits (China)

Beverages
  • Lager beers and stouts (Africa, USA and Australia)

Animal feeds
  • Processed cattle feed (USA and South America)

  • Bird food (Asia and Africa)

  • Poultry feed (Australia)

Animal feeds
  • Formulated dog food (South Africa)

Industrial uses
  • Starch (USA and Africa)

Industrial uses
  • Bioethanol from starch (USA)

Table 8.

Current and emerging uses of millets in the world.

Source: [35].

UsesReferences
Traditional opaque beer, Busa[36]
Bread, porridge, soup, cake, beer and distilled liquors[37]
Light and thick porridge; Beer called pito[9]
Weaning and infant food preparations, dumpling, porridge and roti[38]
Food products: mathri, sevain, kachari, kachauri, laddu, cheela, cheela,biscuits and halwa[39]
Polenta, couscous, medicinal herb, folk remedy for leprosy, liver diseases, measles. Pneumonia and smallpox[40]
Flour- based foods such as roti, muddeand ambli[1, 41]

Table 9.

Uses of millets.

Traditional processing of millet products has received poor scientific applications especially in the developing countries and the use of the modern processing technology has been restricted which can help to produce commercialised products in a large industrial volume [13, 42]. The development of value-added and convenient food products in urban areas may be a possible solution for promoting consumption of millets products. Most of the research have been conducted on the development of composite flour and extruded products which also increase the availability of millet products in the urban areas [1, 43]. Presently, food scientists are more interested in neglected small grains such as finger millet to reduce food shortage and hunger in the developing countries such as Nigeria, Uganda, Kenya, Tanzania, and South Africa. People who are living in the developing countries have limited access to animal food products so it is better to consume healthy millet foods that are rich in minerals and vitamin B complex. Animal food products contain high amount of minerals such as iron and zinc [44, 45, 46].

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4. Traditional millet-based products

Millet grains/flours are consumed as flat bread, porridge, roasted and alcoholic and non-alcoholic beverages. They are utilised to bake different baked products (cookies, biscuits, bread and muffins) and weaning food. Composite flours are utilised to make chappati, puti and murukul, supplementary foods for feeding babies or infants. Some traditional products produced from millets are burfi, baddis, halwaand papad.They are also utilised to replace commonly used cereals in local community dishes like idli, dosa, puttu, adai[27], khichdi, millet ball “fura” and tuwo. Other products that are produced from millet grains/ flours are traditional foods and beverages such as snack, fast foods, millet wine roti, bread (fermented or unfermented), porridge and millet powder [7]. Table 10 shows the most common indigenous millet based fermented food and beverage products produced around the world in which liquid drink is the most popular product and microorganisms associated with each product.

ProductsMicroorganismsRegions
Busa(liquid drink)Lactobacillus, SacchromycesEgypt
Chikokivana(Alcoholic beverage)Sacchromyces cerevisiaeZimbabwe
Dalaki (thick porridge)UnknownNigeria
Doro(colloidal, thick, alcoholic drink)Yeast and bacteriaZimbabwe
Bogobe(solid dough)Lactobacillussp., yeastBotswana and Ghana
Kenkey(solid dough)Lactobacillus sp., yeastBotswana and Ghana
Kwanu-Zaki(liquid drink)LAB, YeastNigeria
Ogi(liquid porridge)Lactobacillussp., AerobacterNigeria
Merissa(alcoholic drink)SacchromycesSudan
Mahewu(liquid porridge)Lactobacillus delbrukii, L. bulgarius, Streptococcus lactisEast African Countries
Munkoyo(liquid drink)UnknownAfrica
Uji(porridge as staple foods)Leuconostoc mesenterodesUganda, Tanganyika
Other fermented products
Traditional opaque beer (Kaffirbeer) and Isidudu Imbila(fermented thin porridge)South Africa
Commercial brewing, opaque beer, mangisi (sweet–sour non-alcoholic drink).Zimbabwe
Nashaor madida(thin porridge).Sudan/Kenya

Table 10.

Most common indigenous millet-based fermented foods and beverages.

Sources: [47, 48, 49, 50, 51].

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5. Non-alcoholic beverage products

Some other non-alcoholic beverage products that are produced form different millet species include appalu, samaipayasamand korramurukulu. Appaluis a food product made from pearl millet and Bengal gram flours. The mixed dough is divided into small balls and flattened into round shape. The dough is fried in a hot cooking pan, then fried and served hot with some vegetables or meat. Samaipayasamis a little millet which is also known as samaiand it means little millet while payasammeans kheer. The food product is prepared by milling roasted groundnuts into fine powder or flour. Little millet is added to boiling water while stirring constantly. After stirring, the jaggery solution is mixed and cooked for a few minutes on low temperature and served hot. Any millet can be used to make this recipe instead of little millet. Korramurukuluis prepared from foxtail millet and Bengal gram flour. The mixed dough is placed by using hand extruder and murukuluextruded is deep-fried until they turn brown [26]. Millet flour can be utilised to produce breakfast meals that are also known as gruels such as “ogi” and “akamu”. They can be consumed with various animal and vegetable products like meat and leafy vegetables that can nourish the human body by providing good nutritional value [52].

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6. Conclusion

In general, this book chapter covered the nutritional composition of millets, processing and utilisation of millets grains or flour into traditional based products and non-alcoholic beverages. Different types of millet such as pearl millet, proso millet, kodo millet, finger millet, foxtail millet and little millet) are currently being utilised for different purposes (bread, cookies, muffins, chapatti and biscuit. The availability of gluten free value-added millet products globally may help mitigate the incidence of celiac disease and obesity. Therefore, there is a need for commercialisation and development of value-added gluten-free food products from millets.

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Acknowledgments

The authors would like to thank, we are changing the funder to Agricultural Research Council: “Human, Research and innovation Capacity Development Initiative (HRICDI)” An Initiative of Department of Science and Technology (DSI), Managed by the “Agricultural Research Council (ARC)”, Title: “Utilisation of traditional processing methods (fermentation and malting) to improve the nutritional value of cereal grains”. Univen grant number, Cost centre E601. Consortium comprises of University of Pretoria & University of Venda, Wageningen University, Finland, Kenya, and Uganda.

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution 3.0 License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Shonisani Eugenia Ramashia, Mpho E. Mashau and Oluwatoyin O. Onipe (December 6th 2021). Millets Cereal Grains: Nutritional Composition and Utilisation in Sub-Saharan Africa, Cereal Grains - Volume 1, Aakash Kumar Goyal, IntechOpen, DOI: 10.5772/intechopen.97272. Available from:

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