Production and Evaluation of the Quality of Pearl Millet-based Fura (A Northern Nigerian Cereal-based Spiced Steamed Dough) as Affected by Bambara Groundnut Flour Supplementation

Fura is a local food of the Hausa/Fulani tribe and is most commonly in the whole of Northern Nigeria. Millet is a general term used for a wide range of cereals that describe several taxonomically divergent species of grass. Millet is thought to be among the first cultivated crops and has been a staple food ingredient in Central and Eastern Asia, Europe (mainly Russia), China, India, and some parts of Africa since ancient times [1]. It is an important food in many developing countries because of its ability to grow under adverse weather conditions such as limited rainfall. In addition, millet has many nutritious and medicinal properties [2]. Pearl millet is an important food for millions of people inhabiting the semi-arid tropics and is a major source of calories and vital component of food security in the semi-arid areas in the developing world [3]. The grain is processed in so many ways for preparation of various food products. Some of the products include, cooked whole grain, thin and thick porridges, steamed cooked grits (couscous, burabusko), Kunun zaki, Tuwo and Fura [4, 5, 6] Other traditionally processed pearl millet based foods in North-Eastern Nigeria include Yartsala, Shinkafan tudu (dehulled boiled millet), Fura, Gumba, Kunun tsamiya, Tuwo, and Nyauri etc. Enrichment of cereal-based food with other protein source has received considerable attention. Fura is solely a cereal-based food which will require the use of a grain legume as a supplement in order to complement the limiting nutrients in millet. Addition of Bambara nut will help to increase in quantity and quality of nutrients, and as well provide good quality essential amino acids in the supplemented fura because Bambara AB ST R ACT


Introduction
Fura is a local food of the Hausa/Fulani tribe and is most commonly in the whole of Northern Nigeria. Millet is a general term used for a wide range of cereals that describe several taxonomically divergent species of grass. Millet is thought to be among the first cultivated crops and has been a staple food ingredient in Central and Eastern Asia, Europe (mainly Russia), China, India, and some parts of Africa since ancient times [1]. It is an important food in many developing countries because of its ability to grow under adverse weather conditions such as limited rainfall.
In addition, millet has many nutritious and medicinal properties [2]. Pearl millet is an important food for millions of people inhabiting the semi-arid tropics and is a major source of calories and vital component of food security in the semi-arid areas in the developing world [3]. The grain is processed in so many ways for preparation of various food products. Some of the products include, cooked whole grain, thin and thick porridges, steamed cooked grits (couscous, burabusko), Kunun zaki, Tuwo and Fura [4,5,6] Other traditionally processed pearl millet based foods in North-Eastern Nigeria include Yartsala, Shinkafan tudu (dehulled boiled millet), Fura, Gumba, Kunun tsamiya, Tuwo, and Nyauri etc. Enrichment of cereal-based food with other protein source has received considerable attention. Fura is solely a cereal-based food which will require the use of a grain legume as a supplement in order to complement the limiting nutrients in millet. Addition of Bambara nut will help to increase in quantity and quality of nutrients, and as well provide good quality essential amino acids in the supplemented fura because Bambara A B S T R A C T Pearl millet flour was substituted with Bambara groundnut flour (0-20%) to form blends and used in fura preparation. Functional and microbiological profiles of the flours and food samples respectively as well as proximate and sensory properties were evaluated. Supplementation had raised the nutritional value of the foods. Swelling power and water absorption capacity had increased with an increase in the level of Bambara groundnut flour addition whereas bulk density and viscosity had decreased; the results were as follows-swelling power (23.616-24.203%), water absorption capacity (3.350-3.650g/g), bulk density (0.791-0.785g/cm3), and viscosity (52.965-50.210mPa-s). The moisture content, ash, fat, protein, fibre, carbohydrate and total energy level were found as follows-42.730-45.500%, 0.510-0.850%, 3.275-7.95%, 3.750-9.375%, 0.775-0.900%, 35.425-48.960% and 240.315-250.750kcal/100g respectively. Concentration of anti-nutritional factors, alkaloids, flavonoids, phytic acids and tannins ranged from 0.09 to 0.15g/100g, 0.28 to 0.35g/100g, 7.31 to 9.83g/100g and 0.04 to 0.16g/100g respectively. The minerals contents were found to be significant as follows Ca (11.55 to 24.35 mg/100g), Fe (2.71 to 5.72 mg/100g), Zn (1.58 to 1.83 mg/100g), P (46.12 to 96.37 mg/100g), Mg (0.63 to 0.77 mg/100g), K (36.19 to 76.89 mg/100g), Na (4.08 to 8.59 mg/100g). In-vitro protein digestibility at 1h ranged between 72.67 to 75.43% and 73.95 to 79.13% at 6hrs‚ starch digestibility ranged between 66.83 to 70.25%. Microbial evaluation revealed moderate counts with the total microbial load of ISSN: 2456-883X www.ajast.net 15 Technology (KUST) Wudil for raw material preparation in the month of January, 2020.

Processing of bambara groundnut
The method of Nkama [12] was used for Bambara groundnut flour production with a slight modification as shown in Figure 1 below.

Blend Formulation and Fura Preparation
The Pearl millet (M) and Bambara groundnut (B) flours were blended in the ratios of 90:10 and 80:20, while 100% Pearl millet served as the control. The blends were thoroughly blended in a kitchen mixer and used to prepare the fura using the traditional method as shown below. Three formulations of Fura blends were produced after using sound pearl millet grains, these were first cleaned to remove debris and sorted to remove unsound grains and other foreign matter, the grains were then de-hulled, and later washed, then sun-dried which reduced moisture content and spices added to improve nutrition and sensory property (Figure 1).

Determination of water absorption capacity
A gram (1g) of the sample was placed into graduated centrifuge tube and 10ml of distilled water was added and mixed thoroughly for 30 seconds. The sample was allowed to stand for 30 minutes at room temperature and then centrifuged at 5,000 rpm for 30 minutes. The volume of the free water was read directly from the graduated centrifuge tube. The water absorption capacity was expressed as grams of water absorbed per gram of sample [13].

Determination of bulk density
This was determined according to the method of Onwuka [13]. A 10ml capacity measuring cylinder was weighed.
The cylinder was gently filled with the sample. The bottom of the cylinder was gently tapped on the laboratory bench several times until there was no further diminution of the sample level after filling to the 10ml mark.

Determination of solubility and swelling power (Sp)
This was determined according to the method of AOAC [14]. 1g of the sample was placed into a cleaned weighed graduated centrifuge tube and 40ml of distilled water added and mixed thoroughly. The mixture was placed on a water bath thermostatically controlled at 85 0 C with continuous stirring for 30 minutes. The sample was allowed to cool to room temperature and then centrifuged at 2,200 rpm for 15 minutes. The supernatant was poured into a pre-weighed crucible and then placed in an oven to evaporate.
The solid residue in the crucible was weighed again and the difference in weight calculated as percentage solubility.
The paste in the tube was then weighed and the swelling power (SP) determined by the following equation:  [14].

Proximate composition of Raw materials, flour blends and Fura Samples
For the determination of proximate composition of fura, raw material (millet, bambara groundnut nut and flour blends of raw materials were determined using procedures of AOAC [14]. Moisture content was determined by drying the sample at 105 0 C for about 3 hours. Ash content was determined by introducing the samples in the crucibles, using a pair of tongs into a muffle furnace at 500 0 C until fully ash. (Grey color ash). Protein content (%N x 6.25) was determined by the Kjeldhal method. Crude fat was determined using the Soxhlet extraction with petroleum ether. Crude fibre was determined using 5 grams of the defatted sample involving alternate digestion with dilute acid and alkali and ashing. Carbohydrate was determined by "difference". Energy (E) values (Kcal) was determined according to the method described by Chinma and Gernah [15]. Energy values: {4x(protein) + 4x(carbohydrate) + 9x(fat)}.

Microbial Analysis
The total bacterial count, the serial dilution method as described by the American Public Health Association (APHA [16] was employed; 5g of the sample was mixed with 225 ml of 0.1% peptone water. The sample was shaken thoroughly to make a homogenate solution, this gave the dilution of 10 -1 . 1ml of this prepared solution was transferred to 9ml of the diluent (0.1% peptone water), this gave the dilution of 10 -2 . This procedure was repeated up to the fifth dilution which gave the dilution of 10 -5 .
Common bacterial pathogens associated with the foods are Escherichia coli-Eosin Methylene Blue (EMB), www.ajast.net 18

Sensory Evaluation
The sensory evaluations of Fura samples were carried out by 20 respondents which comprised of students from the Department of Food Science and Technology, Kano University of Food Science and Technology (KUST) Wudil who are very familiar with the product, some of them are residents of the North-East sub region of Nigeria. The samples were ranked on a 9 point hedonic scale with 1 representing dislike extremely and 9 like extremely as described by [17]. The samples were prepared and served immediately after preparation. Individual samples were presented in a random pattern and judged based on attributes such as: aroma, texture, taste, appearance, and overall acceptability. A glass of clean water was given to the respondents to rinse their mouth in between each determination to avoid discrepancies in taste.

Statistical analysis
Determinations were done in duplicates except otherwise stated and the data generated were subjected to one-way analysis of variance (ANOVA) at 5% (p<0.05) and the means separated using the Least Significance Difference (LSD) method [18]. The statistical analysis was carried out using MINI TAB version 17.

Results and Discussion
There was a significant variation (p<0.05) in the functional properties of the flours and blends ( Table 2). The values of the functional properties generally decreased as pearl millet flour was substituted with bambara groundnut flour. Bulk density ranged from 0.779 to 0.791 g/cm 3 , pearl millet flour had the highest bulk density and bambara groundnut whole grain flour, the least, the results were significantly different (p<0.05) between all the flour samples. The decrease might be attributed to the lower density of bambara groundnut flour compared with millet flour. Plaami et al., [19] reported that bulk density is influenced by the structure of the starch polymers and loose structure of the starch polymers could result in low bulk density. The results obtained in this study was higher when compared with the report of James et al. [20] (2018) who reported a bulk density range of 0.33 to 0.43 g/cm 3 for bambara groundnut-millet-based infant formula, and was also higher than the report of Adebayo-oyetoro et al [21]. on millet-based Fura powder supplemented with bambara nut. Bulk density is the measure of the heaviness of flour and is important in determining the packaging requirement and material handling [22]. Greater quantity of flour in a unit volume translate to greater nutritive value in terms of calorific value.
For the water absorption capacity (WAC), the results ranged from 3.300 to 4.650g/g, bambara groundnut flour had the highest water absorption capacity and the least was in whole millet flour. WAC of fine millet and whole millet flours were not significantly different (p>0.05) but were significantly different from the rest of the formulations.
The high water absorption capacity might be attributed to the higher dry matter content of B f (100:00).
The water absorption capacity in this study increased with an increase in the level of bambara groundnut flour inclusion (0-20%) and this implies addition of bambara groundnut increased the water absorption capacity of the resulting blends which indicated that higher protein content was responsible for higher water absorption capacity (WAC) of bambara groundnut flour. Dietary fibres are known to have higher water holding capacity as seen in B f (100:00). Low water absorption capacity could be an advantage in storage stability as the rate of moisture www.ajast.net 19 absorption could be relatively low hence reduced moisture availability for microbial growth and deleterious biochemical reactions. Proper mixing, consistency of fura requires higher water absorption of the blends which impact positively to the fura sensory attributes.
Swelling power values ranged from 23.512% in millet whole flour to 27.654% in bambara groundnut whole flour.
There was no significant difference between results obtained for fine millet and whole grain flours. The swelling power results increased with an increase in the level of bambara groundnut inclusion in the pearl millet flour. The swelling power results agreed with the report by Agbara et al [22] on millet-bambara bean blends for yartsala production.
The viscosity of the flours ranged from 48.625mPa-s in bambara groundnut flour, and was highest in millet whole grain flour with 56.555mPa-s. The result in this study revealed that increasing the level of bambara groundnut inclusion marginally reduced the viscosity of the flours for the fura production because starch (millet flour) is a better thickener than protein (Bambara groundnut flour) As observed from the results in Table 2, all the parameters determined were related to one another, the lower the bulk density with addition of bambara groundnut, the higher the flours ability to absorb water and the more the swelling power as well as the less the viscosity of the flours. Agbara et al. [23] similarly observed for blends of Yartsala production.  Table 3 shows the proximate composition of millet and bambara groundnut whole grain, the raw material flours and the blends used for the preparation of millet-bambara groundnut fura production. Ash, protein and crude fibre contents increased as the level of Bambara groundnut flour increased (0-20%). This redefines the true state of ISSN: 2456-883X www.ajast.net 20 legume grains being good sources of protein, fat, ash and crude fibre than the cereals [24]. Bambara groundnut has been reported by several authors as being a complete food. The results obtained in this study were found to be higher than the report by Olaleye et al [25] regarding the chemical composition of bambara groundnut ( increase in all the parameters determined other than carbohydrate which decreased as millet flour was increasingly substituted with bambara groundnut flour, the trend for the increase in ash, fat, protein and crude fibre level was expected as bambara groundnut was reported to contain high level of ash, protein and crude fibre [27] High moisture content levels in the food samples might be due to nature of fura processing such as double steaming coupled with the high water absorption capacity of the bambara groundnut flour. This high moisture level indicates higher chance of exposure to attack by micro-organisms therefore its storage potential might be low.  www.ajast.net 21

Mineral Contents of the Flours and Blends
The mineral contents of the fura flour and the blends are presented in  20), and that of Mg, K and Na have been found to be highest in M f (100:00). The high content of Ca and Fe in B f (100:00) might be attributed to the grain"s own composition, being a calcium rich grain, Amarteifio et al., [28] reported that Ca levels ranged from 95.8 to 99.0 mg/100g. Fe result was higher than the report of Léder [29] (2004) who reported Fe content of Pearl millet as 7.49mg/100g and the report of Kulthe et al [30] on millet cultivars who reported iron (Fe) content in millets (2.08 to 8.12 mg/100g). Ca and P are very important in bones and teeth formation, growth, blood clothing, heart function and cell metabolism [31,32]. Inadequate Ca intake results in rickets and risk of osteoporosis as well as hypertension and stroke. Fe values were found higher in this study than earlier reported. Fe is required for oxygen carrying capacity of haemoglobin and myglobin and as a co-factor for several enzymes (NHS Direct online [33]. Deficiency in Fe may lead to anaemia. Ca and Fe levels increased with an increase in the levels of bambara groundnut inclusion. The high content of Mg, K and Na could be linked to the high contents of these minerals in millets. Ca and Mg both plays important role in bone structure, muscles contraction, nerve impulse contraction, blood clothing, cell signaling [34]. Mg has been linked to meeting lower risk of type 2 diabetes. Potassium (K) is important in nerves and muscles function, it helps to offset some of the sodium harmful effects on blood pressure. Sodium is added to foods to maintain water balance in cells and its results were in agreement with the report of Nkama, and Malleshi [35] that reported Na contents of millet flour as 1596ppm (159.6 mg/100g) and the report of Hillrocks et al. [36] on bambara groundnut utilization.

Mineral Contents of Bambara Groundnut Supplemented Pearl Millet-Based Fura and Control
Mineral contents of bambara groundnut supplemented pearl millet-based Fura and control are presented in Table   5b, all the elements (Ca, Fe, Zn and P) analyzed were found to have increased in the Fura products with bambara .89 mg/100g), Na (4.08 to 8.59 mg/100g), this was attributed to millet grain being a good source of these minerals over bambara groundnut grain. Millet flour was reported to contain more K levels than bambara groundnut. K was reported to be in the range of 11.44 to 19.35mg/100g [28,37]. Potassium (K) is important in nerves and muscles function, it helps to offset some of the sodium harmful effects on blood pressure. The high Mg content might be linked to higher Mg in foods made from millet than in bambara groundnut. Ayo and Aba [38] reported that millet based Madidi decreased in Mg content as more bambara groundnut was added. Magnesium is important for healthy bone. Higher intake of magnesium results in higher bone mineral density which is important in reducing the risk of bone fractures and osteoporosis. Olaleye et al. [25]) to range between 11.2 to 40.2 mg/100g higher than the concentration of zinc in pearl millet that is 46.9ppm equivalent to 4.69 mg/100g as reported by Nkama, and Malleshi [35] on Masa production. This might be the reason for the increased zinc content within the foods as Bambara groundnut was added. Zinc is important for the body"s defense/immune system and is important in the synthesis, storage and secretion of insulin [39]. The whole investigation as shown in Table 6a, on the microbiological investigation generally revealed moderate counts. The extent to which a product is contaminated by microorganisms depends on the level of hygiene and sanitary status of handlers and material used in the production chain. Also the degree of humidity of a food material is responsible for the growth or inhibition of microorganisms. Low moisture foods contain no more than 25% moisture and water activity of 0.00 to 0.60 [40]. Bacteria require relatively high level of moisture for growth. This is the reason for low level of counts despite high moisture content.
Microbial findings revealed the total microbial load of 1.23x10 3 cfu/g ( in this study should be of public health concerns because these two have implicated in various diseases of man [41,42,43,44].The percentage occurrences of the bacteria identified in this study showed that Staphylococcus aureus recorded the highest frequency in the fura samples. Moreover, the total bacterial counts recorded from the different fura food samples did not exceed the limits for ready-to-eat foods of 10 2 to ˂ 10 4 cfu/g prescribed by the Food Standards [45] and Centre for Food Safety [46] . The low microbial load recorded in this study is in agreement with the observations by Nester et al. [47] and Adam and Moss [48], who attributed their observations to the low water activity (aw) values of dehydrated foods which are usually below 0.6.  TVC=Total viable count, cfu/g= coliform forming unit per gram, of the food sample www.ajast.net 24

Anti-nutrients Composition of the Flours and the Blends
The anti-nutritional factors of the raw material flours and the blends for fura formulations are presented in Table   7a. Tannin, Alkaloid and Phytic acids contents ranged from 0.18 to 0.25g/100g, 2.75 to 3.50g/100g. and 8.93 to 13.81mg/100g respectively. All the parameters, tannin, alkaloid and phytic acids as anti-nutritional factors in this study decreased with bambara groundnut flour inclusion (0-20%). This is as a result of the low content of anti-nutrients in the bambara groundnut and to its high concentration in the millet flour. The decrease in the tannin content might be attributed to the low content of tannin in bambara groundnut as compared to that of millets. The results obtained agreed with the report of Kulthe et al. [30] who characterized millet cultivars on the basis of some Asna [51] on influence of germination on bio-accessible iron and calcium in pearl millet. Kheterpaul and Chauhan [52] reported pearl millet with a value of 990 mg/100g of phytic acid, Kumar and Chauhan [53] reported value of 825.7 mg/100g, while El-Hag et al. [54] reported a values of 943 and 1076 mg/100g of phytic acid in two Sudanese wheat cultivars. The low phytic acid content could be due to varietal differences and also the effect of processing.
Many processing techniques such as cooking, germination, soaking reduces the contents of anti-nutrients.

Anti-nutrients Contents of the Bambara groundnut supplemented Pearl Millet-Based Fura and Control
The anti-nutritional contents of the bambara groundnut supplemented pearl millet-based Fura is presented in Table   7b. The concentration of alkaloids, flavonoids, phytic acids and tannins ranged from 0.09 to 0.15g/100g, 0.28 to 0.35g/100g, 7.31 to 9.83g/100g and 0.04 to 0.16g/100g. The decrease in the anti-nutritional factors as bambara groundnut was added, was also recorded at products as was seen in the raw materials anti-nutrients analysis.
Alkaloid are active components of stimulants, tranquilizers and are not only in food systems but in also in medicine because they can act quickly in specific areas of the nervous system. The results obtained in this study may be ISSN: 2456-883X www.ajast.net 25 explained that the foods made from millet may have medicinal property. The flavonoids, phytic acid and tannins contents were similar to the report of Owheruo et al. [55] on the physicochemical properties of malted finger and pearl millet where he reported phytic acid content of pearl millet as 910mg/100g, tannin content of pearl millet as 0.10g/100g. Tannin have been reported to lower digestibility of most nutrients especially protein [56]. Flavonoid has been reported to exhibit anti-oxidant activity, the presence of flavonoid in foods, a phenolic compound may contribute to health potential of the food. There was a general decrease in the anti-nutritional content of treated fura when compared with their levels in the raw materials. This might be attributed to the method of processing which the flours were subjected to; soaking, de-hulling, cooking etc. The outlined processing methods have been found to reduce anti-nutrient levels for many seeds.

In-vitro Protein and Starch Digestibility of the Bambara Groundnut Supplemented Pearl Millet-Based Fura and the Control
The in-vitro protein and starch digestibility of the bambara groundnut supplemented pearl millet fura and the control are presented in Table 4 [54] and Taylor and Taylor [59], they observed that combination of fermentation and cooking significantly improved the digestibility of sorghum. The improvement of protein digestibility after boiling was due to the reduction in anti-nutritional factors such as saponins, alkaloids, tannins and cyanide. The starch digestibility decreased with an increase in the level of bambara groundnut flour inclusion into the pearl millet fura. This might be attributed to the high amylase content since high amylase content may reduce starch digestibility [60]. In general, millet protein digestibility can be reduced by several factors, most notably the presence of tannin and dietary fibre (Annor et al., [60], these foods are found to be low in dietary fibre. Mean values in the column bearing the identical superscripts are significantly not different (P>0.05) of duplicate determinations. Table 9 shows the sensory properties of the bambara groundnut supplemented millet-based fura samples. There was no significant difference (p<0.05) in the sensory properties of fura from 100% millet and 90:10% millet-bambra nut fura in appearance, aroma and general acceptability, but the fura samples varied as further level of bambara groundnut (0-20%) was increasingly added except for the general acceptability which maintained no significant difference. Fura from 80:20 (millet-bambara bean) flour blend received best score and most preferred. www.ajast.net 27

Conclusion
In conclusion, fortification of the millet-based Fura, with Bambara groundnut flour (0-20%) had improved the ash, fat, protein and energy contents of fura. The microbial load in the processed fura samples revealed moderate counts which mean that the foods were safe for consumption. Finally the study had succeeded in improving the functional, nutritional quality as well as sensory properties of the millet-bambara groundnut fura. The food can be considered an alternative source of protein and fat not only to inhabitants of the North-Eastern Nigeria but also to any who considers it a food item worthy for consumption. It is recommended that further studies on the modified fura should be based on formulating shelf-stable fura flour as will facilitate the acceptability of fura in other regions of the world. The amino acid profile of the processed fura needs also to be investigated in order to re-assure its nutrient-density t furs consumer.