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

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

### **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 *Gramineae* and they are smallseeded species [1–3]. Most millets belong to the tribe *Panicoideae* apart from finger millet and teff that belong to the tribe *Eragrostideae* [4–6]. 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 [9–11]. 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 [13–15]. 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].

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**.



#### *Millets Cereal Grains: Nutritional Composition and Utilisation in Sub-Saharan Africa DOI: http://dx.doi.org/10.5772/intechopen.97272*

#### **Table 1.**

*Source: [19].*

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


#### **Table 2.**

*Major cultivated millet species.*

### **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

**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].*


#### **Table 3.**

*Various characteristics of millet species.*

[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 *Millets Cereal Grains: Nutritional Composition and Utilisation in Sub-Saharan Africa DOI: http://dx.doi.org/10.5772/intechopen.97272*


#### **Table 4.**

*Functions of millet species.*


#### **Table 5.**

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


#### **Table 6.**

*Proximate composition and mineral contents of some millet species.*


#### **Table 7.**

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

*Millets Cereal Grains: Nutritional Composition and Utilisation in Sub-Saharan Africa DOI: http://dx.doi.org/10.5772/intechopen.97272*

carbohydrates, 5.6–12% protein, fat, 2–5%, 15–20% crude fibre and 2.5–3.5% minerals.

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].

### **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


#### **Table 8.**

*Current and emerging uses of millets in the world.*


#### **Table 9.**

*Uses of millets.*

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**.

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 [44–46].

### **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*, *halwa* and *papad.* They are also utilised to replace commonly used cereals in local community dishes like *idli*, *dos*a*, 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.

*Millets Cereal Grains: Nutritional Composition and Utilisation in Sub-Saharan Africa DOI: http://dx.doi.org/10.5772/intechopen.97272*


#### **Table 10.**

*Most common indigenous millet-based fermented foods and beverages.*

### **5. Non-alcoholic beverage products**

Some other non-alcoholic beverage products that are produced form different millet species include *appalu, samaipayasam* and *korramurukulu. Appalu* is 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. *Samaipayasam* is a little millet which is also known as *samai* and it means little millet while *payasam* means *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. *Korramurukulu* is prepared from foxtail millet and Bengal gram flour. The mixed dough is placed by using hand extruder and *murukulu* extruded is deepfried until they turn brown [26]. Millet flour can be utilised to produce breakfast meals that are also known as gruels such as "*og*i" 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].
