Processing , nutritional composition and health benefits of finger millet in sub-saharan Africa

The term millet is derived from the French word “mille’’ which means thousand, with a handful of millet containing up to 1000 grains (Shahidi & Chandrasekara, 2013). Millet belongs to the group of small-seeded species of cereal crops or grains which are annual plants (Shiihii et al., 2011). Finger millet, a member of the millet group and also known as ragi or tamba (Jideani et al., 1996; Ramashia et al., 2018) is so called due to its growth form of panicles which takes the form of several fingers (Sood et al., 2017). The grain belongs to the family Poaceae which originated in Ethiopia and the sub-family Chloridodeae (Pradeep & Sreerama, 2015; Sood et al., 2016; Ramashia et al., 2018). Different cultivars of FM grain exist: brown, light brown and white (Devi et al., 2014; Kumar et al., 2016), with grain colour used as the distinct means of cultivar differentiation. The white cultivars have been developed mainly for the baking industry, the brown and light brown types used for porridge while the brown cultivar is utilised for brewing traditional opaque beer in Southern Africa (Sood et al., 2017).


Introduction
The term millet is derived from the French word "mille'' which means thousand, with a handful of millet containing up to 1000 grains (Shahidi & Chandrasekara, 2013).Millet belongs to the group of small-seeded species of cereal crops or grains which are annual plants (Shiihii et al., 2011).Finger millet, a member of the millet group and also known as ragi or tamba (Jideani et al., 1996;Ramashia et al., 2018) is so called due to its growth form of panicles which takes the form of several fingers (Sood et al., 2017).The grain belongs to the family Poaceae which originated in Ethiopia and the sub-family Chloridodeae (Pradeep & Sreerama, 2015;Sood et al., 2016;Ramashia et al., 2018).Different cultivars of FM grain exist: brown, light brown and white (Devi et al., 2014;Kumar et al., 2016), with grain colour used as the distinct means of cultivar differentiation.The white cultivars have been developed mainly for the baking industry, the brown and light brown types used for porridge while the brown cultivar is utilised for brewing traditional opaque beer in Southern Africa (Sood et al., 2017).
The grain is a semi-arid region crop cultivated in dry areas with limited rainfall and can adapt to various agro-climatic conditions (Gull et al., 2014).Period of cultivation of the grain is February and August with the period of harvest set in June or Finger millet grains are gluten-free, non-acid-forming (Muthamilarasan et al., 2016), easy to digest with low glycemic index foods (Manjula & Visvanathan, 2014).Ots low glycemic index food property is reported to be a good choice for people with celiac disease (disease caused by gluten-containing cereal protein ingestion) and diabetes as consumption of the grain assist in the regulation of blood glucose level (Jideani & Jideani, 2011).The grains consist of nutrients: dietary fibre, carbohydrates, iron and calcium in high concentration when compared to other cereal grains (Sood et al., 2016).Finger millet grains also contain high amount of magnesium and phosphorus.Absorption and utilization of these nutrients in the human body contributes to the reduction of chronic diseases such as lowering of high blood pressure, ischemic strokes, cardiovascular diseases, cancers, obesity and type OO diabetes (Kaur et al., 2014;Ramashia et al., 2018).Krishnan et al. (2012) reported that FM grains contain polyphenols and phytates which are known to influence the availability of minerals.
Processing of FM grains comprises both the traditional and modern methods.The traditional method of processing can be employed in the manufacture of value-added products such as soaked, cooked, malted, papad, fermented, popped or puffed, extruded and multi-grain flour (Sood et al., 2017).Traditional method of FM processing also includes a method of spreading and drying the grains in the sun for a period of one week.Upon drying, the grains are stored in a bag and later used for the processing and manufacture of different food products (Young, 1999).Dried FM grains can be stored for more than 5-10 y, but a major hurdle is that the grains are very tiny and not easy to handle.The grains are resistant to diseases and insects but are easily invaded by fungal disease (Usai et al., 2013;Sood et al., 2016).Despite its usefulness and health beneficial properties, there is little research and innovation on FM grains/ flours as compared to conventional cereal grains such as maize, sorghum, rice and wheat.This study therefore reviews the processing, nutritional and health benefits of FM as well as its use in value-added products.

Sudan
Telebun, akima, bek, mataighio and kal.Shimelis et al. (2009), Blench (2012).instead of a true caryopsis, thus making the pericarp not to be completely fused with the testa.Similarly, the structure of other millets such as pearl, foxtail, fonio and teff millet are regarded as caryopses.The term caryopses refers to a single-seeded fruit in which the fruit coat or pericarp surrounds the grain, adheres tightly to the grain coat (Wrigley & Batey, 2010) and has a brick red-coloured seed coat (Patel et al., 2014).
The uniqueness of FM grain imparts a characteristic of allowing the pericarp to be easily removed upon rubbing the grains with mortar and pestle.Another unique structural characteristic of FM grain is its five (5) layered-testa which has been implicated as one of the likely reasons for the presence of a high dietary fibre content in the grain (Shobana et al., 2013).The principal anatomical parts of the FM grains are pericarp, germ and the endosperm (Figure 1).The pericarp is an outer thin layer which covers the grain and it is known as the glume.The grain pericarp consist of three (3) layers with varying thickness: the epicarp (outermost layer), mesocarp (middle layer) and endocarp (inner layer) (Siwela, 2009;Wrigley & Batey, 2010;Ramashia, 2018).
Prior to further processing, the pericarp is removed from the kernel because it is a non-edible tissue (Patel & Verma, 2015).The endosperm forms the largest anatomical component of the kernel.Endosperm is attached to the seed coat and is used in the production of flour (Palanisamy et al., 2012).

Nutritional, antioxidant properties and potential health benefits of finger millet grains
Finger millet grains are said to contain essential minerals such as calcium (Ca) and phosphorus (P).The grains contain the highest amount of Ca, ranging from 162.0-358.0mg/100 g when compared to other millet species (Roopa & Premavalli, 2008;Manjula et al., 2015).Calcium which is predominantly present in FM, plays an essential role in growing children, pregnant women, the elderly (Jideani, 2012;Chappalwar et al., 2013) as well as in people suffering from obesity, diabetes and malnutrition (Jayasinghe et al., 2013;Manjula et al., 2015).Deficiency of Ca in the body can be mitigated by consuming FM food products in the daily diet of both young and elderly people (Towo et al., 2006).Phosphorus, another mineral present in FM, contributes to the development of body tissue and energy metabolism (Vanithasri et al., 2012;Ramashia et al., 2018), with concentration of P in FM ranging from 130.0-283.0mg/g.Dther minerals present in FM grains include iron with a concentration of 3-20% (Rajiv et al., 2011;Shukla & Srivastava, 2014) and magnesium implicated for the reduction of high blood pressure, severity of asthma, frequency of migraines and the risk of heart attack (Saleh et al., 2013;Verma & Patel, 2013;Prashantha & Muralikrishna, 2014).On comparison with other millet species, FM grains are more nutritious (Upadhyaya et al., 2011;Adhikari, 2012;Shobana et al., 2013;Devi et al., 2014;Dlamini & Siwela, 2015), with higher mineral content and proximate composition (Table 3), though the grain is still extremely neglected and widely underutilized (Roopa & Premavalli, 2008).Vitamins which are other nutrients present in FM grains are important micronutrients required by the human body for normal growth and self-maintenance.Vitamins are grouped into categories such as fat and water-soluble vitamins and a lack of vitamins may lead to vitamin deficiencies which can cause health problems (Dttaway, 2008;Dionex Corporation, 2010).Finger millet grains possess fat and water-soluble vitamins and are rich in vitamins A and B complex (Table 4) (Chappalwar et al., 2013;Devi et al., 2014).However, vitamin C is absent in the dried grain (Siwela, 2009).Finger millet grains contain 44.7% of essential amino acids (Singh & Raghuvanshi, 2012) including methionine, cysteine and tryptophan (Jideani, 2012;Manjula et al., 2015;Ramashia et al., 2018), lysine (Mamatha & Begum, 2013); isoleucine, leucine and phenylalanine (Sood et al., 2017) as well as threonine (Table 5) which helps to lower cholesterol levels and reduce risk of cancer and obesity in the human body (Mathanghi & Sudha, 2012;Thapliyal & Singh, 2015).The grains contain the highest amount of methionine (194 mg/g) when compared to other millet species (Singh et al., 2012;Prashantha & Muralikrishna, 2014).
Finger millet grains also contain essential fatty acids such as linolenic and palmitic acids which are essential for the development of brain and neural tissue (Kunyanga et al., 2013;Muthamilarasan et al., 2016).Fat which contributes to better storage properties and helps to prevent obesity risk, and/ or regulate body weight (Singh et al., 2012;Verma & Patel, 2013;Gunashree et al., 2014), has low occurrence (1-2%) in FM grain.Conversely, other millet grains contain higher amount of fat ranging from 3.5-5.2%(Shahidi & Chandrasekara, 2013).Low fat content together with dietary fibre and higher amounts of carbohydrates which are available in the form of non-starchy polysaccharides are essential in providing nutritional and physiological benefits such as hypocholestrolaemic and hypoglycemic effects (Vanithasri et al., 2012;Banusha & Vasantharuba, 2013).Dietary fibre which  contributes to high nutritional and functional importance is also present in FM grains.Dietary fibre which is classified into cellulose, pectin, arabinoxylan, lignin and β-glucan (Prashantha & Muralikrishna, 2014), assist in determining the end-use quality of cereal-based food products.
Tryptin inhibitors, phytate, phytic acid, tannins and flavonoids which are present in FM grains are reported to contribute in reducing the bioavailability of minerals which brings about a reduction in the nutritional quality of FM (Palanisamy et al., 2012).However, phenolic acids and tannins are the main polyphenols present in FM, while flavonoids are reported to be available in small amounts.Polyphenols are regarded as major antioxidants that conduct activities which help to maintain the body immune system.Polyphenols occur naturally in a wide range of food products including FM grains (Siwela et al., 2007;Devi et al., 2014;Udeh et al., 2017).Tannins in the outer layer of the grain, serves as a physical barrier to fungal invasion (Devi et al., 2014) and plays an important role in the biological function of plants and humans.However, their anti-nutritional effects are partly negative because they reduce the digestibility of nutrients and the absorption of minerals.Recent studies have shown that some processing methods such as malting, fermentation, decortication, soaking, and steaming can improve the bio-availability of these nutrients (Sood et al., 2017;Sripriya et al., 1997;Platel et al., 2010;Krishnan et al., 2012;Dharmaraj and Malleshi, 2011).Tannins also inhibit growth because of their negative influence on the function of pancreases, the thyroid gland and can result in pathological alteration of the liver.Tannin compounds have been reported to affect colour, flavour, nutritional quality of the grains and products prepared from FM (Table 6).The compound also contributes to the antioxidant activity of FM foods which has been an important factor in healthy aging and the prevention of metabolic disease (Shibairo et al., 2014).
Health benefits of FM grains include slow release of glucose into the blood stream during digestion (Chappalwar et al., 2013;Mamatha & Begum, 2013) as well as its effect in reducing constipation (Vanithasri et al., 2012).Finger millet grains are also reported to be associated with lowering the risk of diabetes, reduction of blood pressure and cardiovascular diseases (Pradeep & Sreerama, 2015).Consumption of the grain has also been reported to reduce the risk of cancer (Subastri et al., 2015) and help to lower cholesterol levels (Table 6) (Asharani et al., 2010).Finger millet starch is used in the pharmaceutical industries as a binder for the preparation of granules and capsule dosage forms (Shiihii et al., 2011).Dther benefits of FM are development and repair of body tissue, prevention of gallstones, protection against breast cancer and protection against postmenopausal women and childhood cancer (Verma & Patel, 2013).The grains are also consumed as whole grains, are easily digestible and taste good (Thapliyal & Singh, 2015).Finger millet grains are among the most important cereal grains for low socioeconomic communities especially Africa and some parts of Asian countries due to the grains serving as good sources of vitamins and fatty acids (Das et al., 2012;Verma & Patel, 2013;Rurinda et al., 2014).

Processing methods of finger millet grains
Processing of FM grains through modern and traditional means, assist in converting the grains to edible forms of food products.Traditional forms of processing the grains include soaking, germination, malting, fermentation, milling or grinding, cooking, roasting and popping or puffing (Table 7) carried out mostly in rural areas (Hemalatha et al., 2007;Saleh et al., 2013;Dutta et al., 2015).The traditional processing of FM food products has received poor scientific applications especially in the developing countries.Thus, the use of modern processing technology in the manufacture of commercial products from FM is required (Saleh et al., 2013;Subastri et al., 2015).
Availability of value-added convenience food products from FM grains/ flours in urban areas promotes its consumption (Gunashree et al., 2014).Most research on FM has been conducted on the development of composite flours and extruded products which also increases the availability and awareness of FM food products in urban areas (Patel & Verma, 2015).Presently, food scientists are more interested in neglected minor grains such as FM in order to reduce hunger and food shortage in developing countries.Accordingly, a huge percentage of people living in developing countries have limited access to animal food products, hence the need to consume highly nutritional FM food products that contributes significantly to their health (Tripathi & Platel, 2010;Akhtar et al., 2011;Kunyanga et al., 2013).Lowering of blood pressure and diabetes.Decreases tumour.Siwela et al. (2007), Thilagavathi et al. (2015).

Nutraceutical foods
Promotes better health by reducing the risk of chronic disease such as obesity.Lowers blood pressure, cancer and diabetes.Sarita & Singh (2016).

Magnesium
Reduces the risk of heart attack.Chandra et al. (2018).

Phosphorus
Essential for the development of body tissue and energy metabolism.Chandra et al. (2018).

Soaking
Soaking is a process of adding distilled water to FM grains until the grains are fully steeped in water and left for an overnight period at an ambient temperature of 30 to 60 °C.The soaked water will then be discarded and the FM grains thoroughly cleaned and washed using clean water to remove foreign materials.The washed grains are then dried in a hot air oven at 60 °C for 90 min before milling to flour (Banusha & Vasantharuba, 2013).Soaking thus reduces the availability of antinutritional compounds such as phytic acid which increases the bioavailability of minerals like zinc (Saleh et al., 2013).

Germination
Ot is a traditional process where the whole unhusked grains are soaked for 2-24 h and then spread on a damp cloth for up to 24-48 h or incubated at 30 °C for 48 h (Shimray et al., 2012).Germination process has been operated at low cost without the use of expensive equipment and it is an easily adaptable technology.Germination has been used for centuries to soften the kernel structure and improve the nutritional composition and concentration of carbohydrates, minerals, vitamins and essential amino acids, thus increasing the functional properties of the grains (Mbithi-Mwikya et al., 2000;Chove & Mamiro, 2010;Pushparaj & Urooj, 2011).

Malting
Ot is a combined process of steeping, germination, drying, toasting, grinding and sieving in order to achieve high nutritional quality, better starch digestibility, sensory properties and reduced antinutritional activities (Table 7).Malting improves the fibre, crude fat, vitamin B, C and mineral content in the grains, while antinutritional activities of tannins and phytic acid in brown millet are decreased significantly.Malting is a common technology used in Africa as malted FM grains are considered of best quality when compared to malted sorghum and maize (Banusha & Vasantharuba, 2013;Sarkar et al., 2015;Thapliyal & Singh, 2015).Dlamini & Siwela, (2015) reported that malted FM millet is produced in small scale among rural dwellers to brew local beverages.The brewed grains are then used for refreshment during community ceremonies and for consumption by farmers engaged in farming activities (Rurinda et al., 2014).

Milling or grinding
Ot is the most common traditional processing method that converts dried and moistened cereal grains into flour by using wooden or stoned mortar and pestle.Milling or grinding is normally practiced in developing countries by mostly women (Young, 1999).The milling process of grains consists of sorting, cleaning, hulling, branning and kilning for further processing (Rasane et al., 2015).Finger millet grain requires dehulling and debranning before consumption because FM grain contains large portions of husk and bran.During milling process, about 10% of water is added to the grain in order to facilitate the removal of fibrous husk.Milling is mostly done to remove the fibrous coarse bran or the seed coat of the grains.Furthermore, removal of some phytochemicals such as phytates and tannin during milling improves the bioavailability of iron (Singh & Raghuvanshi, 2012).Ogi (thin porridge), beverage and non-beverage drinks.

Cooking
Makes food palatable and safe for consumption.
Onactivates practically all the anti-nutritional factors that are heat labile.
Puffing or popping Omproves the nutritional value of foods.Enhances appearance, colour, taste and aroma of the processed raw materials.
Snack, breakfast cereal and ready-to-eat foods.

Roasting
Omproves the nutritional quality and shelf-life of foods.

Radiation
Omproves the nutritional quality of foods.Reduces the antinutritional compounds in food.Used for preservation of foods.

Extrusion
Production of precooked and dehydrated foods.
Helps solve the problem of malnutrition.

Composite flour/ Multi grains
Omproves food with low cost.Processing of local food formulations.
Dther methods of milling includes the use of modern and conventional equipment/ machines, conventional stone mills, burr mills (steel or emery type), hammer mills and ball mills.Upon completion of the milling process, the fine flour obtained is used for preparing chapatti while the coarse flour is normally used in the preparation of mudde, a compact ball made from FM dough (Table 7) and pez, a thin porridge or gruel (Patel & Verma, 2015).

Fermentation
Fermentation is a processing method widely used on FM grains whereby the raw material becomes the medium of growth for the microorganism.The fermentation process as a means of food processing has been employed traditionally and continues to be applied in the production of fermented foods and beverages in homes, villages and in small-scale industries (Dsungbaro, 2009).Finger millet may be fermented at room temperature for 24 to 72 h depending on the product or beverages intended to be produced.The most common indigenous FM based fermented food and beverages are produced in Africa (Ranasalva & Visvanathan, 2014).
Presently, fermentation process has been upgraded and is now used in commercial industries to provide value-added products that meet the needs of the urban populace.Ot is also an economic process used for preserving food products (Blandino et al., 2003).During the fermentation process, growing microorganisms produce their own byproducts such as acids or antibiotics as they break down starch.This process in turn inhibits spoilage and pathogenic microorganisms, improves amino acid balance as well as the sensory quality and nutritional value of the grains (Ranasalva & Visvanathan, 2014).Fermentation also provides health benefits by reducing antinutritional compounds such as tryptin, amylase inhibitor, phytic acid and tannins in cereal grains (Rasane et al., 2015).Ot should however be noted that each product of FM fermentation is associated with specific microorganisms (Table 8).

Cooking
Ot is a processing method that involves boiling FM grains in water until the grain becomes soft, mashed and again mixed with water to give a final product soup.Grueling helps to reduce the microbial load and improves the desirable sensory quality of the cooked grain (Khamgaonkar et al., 2013).Cooking of FM grains can also be prepared by mixing boiled water and flour to produce porridge (Emmambux & Taylor, 2013).

Puffing or popping
Puffing or popping is a traditional method used for producing ready-to-eat and stable shelf-life products which are crunchy and porous (Singh & Raghuvanshi, 2012;Dutta et al., 2015).Puffing also involves soaking whole unhusked grains in water and mixing with sand heated at 250 °C for 15-60 s. (Sarkar et al., 2015;Thapliyal & Singh, 2015).Puffed snack foods are desirable in terms of colour, texture, flavour and shape thereby enhancing consumer acceptability.
Presently, modern air puffed machines have been developed for the mass production of puffing millet grains.Puffed FM can be milled to flour and further enriched with additional ingredients (Thapliyal & Singh, 2015).Finger millet popped products have been reported to improve the pleasant aroma, acceptable taste and quality of grains by inactivating destructive bacteria (Thapliyal & Singh, 2015).Puffing on its part, increases the digestibility and solubility of starch due to gelatinization (Table 7).Puffing also increases the dietary fibre of the final products and decreases antinutritional factors (Choudhury et al., 2011;Sarkar et al., 2015).

Roasting
Ot is a simple traditional technology commonly practiced in households and rural areas.Roasting is similar to puffing process but differs in the volume expansion which is higher in puffing.During roasting, the antinutritional or toxic effect such as saponins, alkaloids, glycosides, gioterogenic agents, tryptin inhibitor and hemagglutinin are removed.Roasting improves the nutritional quality and increases the shelf-life of the roasted grains (Table 7).Processed foods obtained as a result of roasting of FM grains include weaning foods which increases the bioavailability of iron (Singh & Raghuvanshi, 2012;Thapliyal & Singh, 2015).

Extrusion
Ot is a modern food processing method applied to foods and used in solving problems associated with the processing of small cereal based products in terms of physical state, quality, functionality and shelf-life extension (Table 7).Extrusion process has many advantages in terms of preparation of ready-to-eat foods desired in different shapes, size, texture and sensory characteristics (Vanithasri et al., 2012;Dhurve et al., 2015).Extrusion has also found application in solving the problem of malnutrition in developing countries due to its beneficial process.The cooking process employed is high temperature for a short time which is used in processing starchy materials.Common advantages of extrusion cooking include low cost, high productivity, speed and high product quality.Extrusion also assists in product development without waste, increases in-vitro protein digestibility, versatility, unique product shapes and energy savings (Manjula & Visvanathan, 2014;Divate et al., 2015;Gat & Ananthanarayan, 2015).During the extrusion process, protein solubility and structure are decreased and disrupted when applied under high pressure and temperature (Manjula & Visvanathan, 2014).Extrusion is a process of gelatinizing and cooking the product completely until it is fully cooked, thereby leading to the production of different forms of food.
The extrusion process is extensively applied in food industries to make breakfast cereals and snacks.Flour from various plant sources can be prepared in different forms to produce common extruded products such as snacks, noodles, macaroni, spaghetti, baby foods and pasta which are preferred by children and teenagers.Furthermore, this technology can be applied in the preparation of pet foods which are very convenient and requires short time to prepare.Snacks are ready-to-eat products which are very popular and whose demand is increasing among all age groups (Limsangouan et al., 2010;Siddhart, 2014;Thapliyal & Singh, 2015;Masli et al., 2018).Fortification of extruded products with minerals and vitamins is also employed to balance the nutritional composition that is lost during processing and to prevent micronutrient deficiencies (Towo et al., 2006;Dttaway, 2008).The extruded products can be coated with sweet or savory flavors to appeal to children (Mariotti et al., 2006;Thapliyal & Singh, 2015).

Radiation process
Food irradiation technology is a process in which packed foods are subjected to controlled ionizing radiation in the form of x-rays, alpha, beta and gamma rays (Manjula et al., 2015).The technology is also in the preservation of foods by extending their shelf-life.This contributes to better quality products, improves the nutritional quality of foods and reduces antinutritional compounds (Singer et al., 2006;Pushparaj & Urooj, 2011;Rodrigues et al., 2014).Food irradiation has been recommended by other researchers as an efficient, potential food preservation process used in food processing industries.The United States, France, Canada and United Kingdom are among 42 countries which have been given clearance to use radiation in their food processing industries (Manjula et al., 2015).
Traditional processing technologies such as germination, soaking, fermentation, puffing and cooking reduces the level of tannins and phenols while increasing the bioavailability of micronutrients (Devi et al., 2014;Gunashree et al., 2014;Sarkar et al., 2015).However, new processing and preparation methods are needed to enhance the bioavailability of micronutrients and improve the quality of millet diets in humans (Pradeep & Sreerama, 2015).The commercialisation of FM food products that may be consumed by people, especially those suffering from celiac disease and diabetes is important more so as the demand for gluten-free food product is increasing in urban areas (Angioloni & Collar, 2012).

Compositing finger millet flour and bakery products
Composite flour is a technological process of mixing wheat flour and flour from other cereal grains such as finger millet (Devani et al., 2016).Compositing is usually applied in the preparation of bakery products including biscuits, muffins, rusk, cakes and bread which possess good texture, appearance, flavour and sensory acceptability.The processing technique has also been used by mixing non-wheat flours, roots and tubers and other raw edible materials.Compositing has equally found application in the fortification of one material with another for enhanced nutritional quality and sensory attributes (Rajiv et al., 2011;Thapliyal and Singh 2015).Studies have been conducted where FM flour was combined with wheat flour to produce baked products and pastries (Singh et al., 2012;Sawant et al., 2013;Noorfarahzilah et al., 2014).The specified ratios of compositing leads to an increase in the concentration of proteins, fat, phosphorus, dietary fibre, calcium, ash content, tannin and phytic acid in the final processed food product (Chhavi & Savita, 2012;Thapliyal & Singh, 2015).Furthermore, Shahidi & Chandrasekara (2013) and Patel et al. (2014) reported that most research on multigrain products have been focused mostly on gluten-free products and are regarded as the present day niche focus areas or markets.

Use and application of finger millet grains/flours
Finger millet grains are used primarily in the production of traditional foods such as alcoholic and non-alcoholic beverages (Table 8), while its flour is utilised in the manufacture of different types of FM value-added food products (Figure 2).The grains are also used in the preparation of geriatric, infant and health foods both in the natural and malted form (Kulkarni et al., 2012).Most food products of FM grain or flour origin are not commercialized, especially those produced in the developing countries.Conversely, food products obtained from sorghum and wheat are commercialised and sold in supermarkets or retail shops around the world (Roopa & Premavalli, 2008;Siwela, 2009).Towo et al. (2006) reported that foods prepared from grain/flour of FM differ from country to country and occasionally from region to region.Abulude et al. (2005) also reported that FM grains are not toxic to health at any stage of consumption yet, FM grains are neglected despite their nutritional advantages.Some recent studies on FM grain highlighting opportunities for research, utilisation and health benefits in developing countries are presented in Table 9.The foregoing discussion shows that more research needs to be conducted on FM grains, especially in the developed countries, with research on FM focusing on the increased consumption of the grain products in developed countries (Jideani, 2012;Amadou et al., 2013).This may help in reducing the occurrence of ischemic strokes, cardiovascular diseases, cancers, obesity and type OO diabetes especially among elderly people living in these countries (Kaur et al., 2014).

Previous studies
Research gap References Gaps in knowledge, needs and opportunities for new research and development of proposal for the formation of network of scientific and research programmes in the world on FM.
Technology needs to be applied to commercial development as African urbanization is increasing the demand for processed, value-added, convenience food products that meets the need of the urban consumer.Development and commercial industries that can produce traditional African FM foods.Belton & Taylor (2004) Utilization, health benefits and value-added products made from FM (tamba) Commercialisation, encouragement and increase in the consumption of fortified FM in urban areas is needed.Jideani (2012).
Focused on the nutritional characteristics, health benefits and developing value-added products from millets.
Future trends should focus on millet consumption in developed countries that could help its industrial revolution.Amadou et al. (2013).
Processing, nutritional quality, improvement of FM grains and their food products.
Availability, use of millet grains in urban areas and opening of new markets for farmers in order to improve their income.Development of highly improved products from millet is also needed.New processing and preparation methods are needed to enhance the bioavailability of the micronutrients and improve the quality of millet diets in human.Saleh et al. (2013).
Discussed the few value-added food products incorporating ragi and simultaneous attempts to enlist and document the methodology and techniques in the interest of scientist and common masses.
Modern trends for the development of new food products.Aspires for complementary foods in order to fulfill the widening gap of food availability and nutritional security.Verma & Patel (2013).
The FM was incorporated with noodles for the management of diabetes disorders.
Commercialisation of FM food products that may serve the people suffering from diabetes is important.Shukla & Srivastava (2014).Omprovement of agricultural production and food security as well as conservation of environmental resources and assistance to farmers to cope with increasing climatic stresses in future.
Educate the community and farmers on the importance of indigenous food products, especially the nutritional composition.Abraham et al. (2014).

Conclusion
The grain FM can be seen to contribute to food security, especially for low income populations across the globe.Focus of previous research on traditional FM products and not on commercialized processed FM products, has made information on innovative research of FM to be scarce.This is more so when comparing studies on FM with that of other major cereals such as maize, wheat and rice.Moreover, the nutritional and health benefits of FM confer on this gluten-free cereal a huge potential for commercial exploitation.Though a lot of improvement still needs to be done in the commercialisation of African FM foods, ways of increasing utilization of the grains through traditional and commercial methods are also needed.There is thus a necessity for further research on FM by food scientists, government agencies, non-governmental organizations, research institutions and industries to generate more information on FM utilization.Commercialisation and development of value-added fortified FM and other gluten-free products holds a lot of potential as the availability of commercialised FM products in developed countries will assist in mitigating the incident of celiac disease and obesity.

Table 2 .
African countries that produce millet grains in thousands per tons from 2010-2014.

Table 4 .
Major vitamin content and fatty acids of finger millet.

Table 5 .
Essential and non-essential amino acids of finger millet.

Table 6 .
Potential health compounds of finger millet.

Table 7 .
Technological processes of finger millet food products.

Table 8 .
Common indigenous millet-based fermented foods and beverages.

Table 9 .
Odentified research gaps on scientific investigation of finger millet grains/flours.