Study and Formulation of Composite Flours Based on Gluten Flour and Local Cereal Flours: Fonio, Millet and Sorghum ()
1. Introduction
The use bakery products made from wheat flour, particularly bread, in people’s diets is now a major concern, and even non-wheat-producing countries today among the major demanders of this product. This important food product (wheat) is the exclusivity of the producing countries, which at the time of the economic crises, provoke an opportunistic increase in wheat prices like at marketing [1] [2] [3] . In 2022-2023, despite a bearish campaign on wheat prices, the price has remained unchanged, and even a rebound at ?38/tons [4] . This situation is causing non-producing countries to devour huge amounts of foreign currency on wheat imports. The Republic of Guinea is a major importer of certain cereals such as rice and wheat, with almost: 544,135 and 532357.14 metric tons of rice and wheat flour per year, despite the presence in the country of two wheat flour processing units (Moulins d’Afrique and Grands Moulins de Conakry) which also import the raw material [5] . However, local agricultural production of all the country’s species: fonio, millet, sorghum, rice, tubers and others is estimated at 7,309,844 tonnes, or approximately 8 million tons if other sources of breadmaking materials such as plantain are taken into account [6] . This trend could diminish if these available cereal and legume sources are processed into flours to partially or totally replace wheat flour in the baking industry [7] . To this end, various techniques for processing cereals (fonio, millet, sorghum, rice and tubers) in different forms and possible substitution of the wheat flour are growing gradually in Republic of Guinea and in many other African countries [1] . In the same order of ideas, numerous studies have been reported on techniques for formulating numerous types flours for cakes and breads in which part of the wheat flour is substituted by flours from local produce [8] [9] [10] [11] [12] . Indeed, taking the example of the cereals like as fonio, millet and sorghum, their chemical composition is similar to that of wheat flour, the only difference being that they do not contain gluten, the protein responsible for the bread-making properties of all flours, which can be incorporated into these local flours to produce better-quality breads. This is why the strategy advocated by the FAO since 2008 encourages the use of these local resources available for partial or total substitution of flour of all kinds, with a view to reducing dependence on imports [4] [7] . The aim of this study is to continue the previous work carried out by our predecessors in the formulation of flours of all kinds from our local products, by formulating three different flours with the incorporation of 10% wheat flour in the flours of fonio, millet and sorghum (90%) for bread-making, follow up to carry out a physico-chemical analysis of the flours formulated and the breads produced. It should be noted these cereals used in this study, fonio is the least well known, but is one of the preferred crops of some West African countries. It is an herbaceous plant belonging to the grass family (Poaceae), with tiny seeds measuring around 1.5 mm and measure 80 cm in length. It is mainly consumed in certain regions of West Africa because of its ease of digestion and its tolerance for people allergic to gluten [13] .
2. Materials and Methods
2.1. Materials
The composite flours produced from the cereals (Fonio, Sorghum and Millet) yeast and glutens flour used in this study were purchased from the locations indicated in (Table 1) and taken to the food technology laboratory of the Gamal Abdel Nasser University in Conakry (Republic of Guinea) (Table 1).
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Table 1. Origin of local flours and gluten.
Equipment
● Péntrin
● Pastry cutter
● Thermometer
● Mechanical scale
● Oven (Fungand model topelec)
● Baker’s blade
● Flour brush
● ChemDraw Ultra 7.0
2.2. Methods
2.2.1. Preparation of Cereal Flour
The cereal flours were produced in accordance with (Diagram 1).
Grain from the reception area undergoes the treatment shown in (Diagram 1). This is followed by polishing to remove the embryonic husk. The seeds are then soaked for an average of 3 to 12 hours. They are then drained and re-dried. This operation is immediately followed by milling, which extracts the flour. After sifting, the flour is roasted to further reduce its water content. The resulting flour is packaged in 1, 5, 10 or 50 kg packs, then sealed and packed in cartons or on pallets.
2.2.2. Formulation of Composite Flours
Composite flours are obtained by mixing gluten and flour from the cereals used in this study in the proportions: 90% flour: 10% gluten as shown in (Table 2). The mixture was homogenized using a Philips mixer (HR2811 model). The result is 100% wheat flour-based composite flours. The coloration of the composite flours is rectified by adding turmeric flour to each of the local flours.
2.2.3. Assessment of the Nutritional Quality of Composite Flours
Dry matter and ash contents were determined by oven-drying at 105˚C to constant weight using the NF V03-707 method [14] . Proteins were determined by the traditional Kjeldahl method [15] . Carbohydrates and fiber were determined by the AOAC 985-29 method. Micronutrients, iron and zinc were determined by UV-VIS spectrophotometry (DR 5000; HACH et LANGE, France). Lipids were determined using the Soxhlet gravimetric method. The gluten content of the composite flours was determined as described:
Diagram 1. Scheme of the flour preparation process of the cereals used in this study.
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Table 2. Composite flour formulations.
Operating mode
Weigh 33.33 g of flour, mix with 17 ml of water (kneading the dough to form the dough piece) and the resulting 10 g flour dough piece was washed with a 2% NaCl solution. The resulting mass was wiped dry, weighed, oven-dried at 120˚C for 2 hours, cooled in a desiccator and then reweighed [16] . The mass of gluten obtained is determined by the formula:
Or m: weighed mass.
2.2.4. Analysis of Functional Properties
● Water absorption capacity (WAC)
It is determined according to method [17] . Which consists of: Take 1 g (m0) of flour to disperse in 10 ml of distilled water. Shake for 30 minutes using a KS10 shaker, then centrifuge the mixture at 4500 rpm for 10 minutes. Weigh the wet pellet collected (m2) and dry at 105˚C to constant weight (m1). The water absorption capacity (WAC) was then determined using the formula:
● Oil absorption capacity (CAH)
It is determined according to the method of [17] [18] . Which consists in taking 1 g (m1) of flour to be dispersed in 7 ml of refined palm oil. Shake for 30 minutes using a KS10 shaker, and centrifuge the mixture at 4500 rpm for 10 minutes. Weigh the wet pellet collected (m2) and dry at 105˚C to constant weight (m3). The water absorption capacity (WAC) was then determined using the formula:
2.2.5. Determining the Baking Value
It represents all the plastic properties of doughs intended for bread-making, and is carried out using the CHOPIN alveograph. These tests are covered by standard NF ISO 5530-4: 2002.
● Operating mode
The method consists in gradually moving a fragment of mass dough in the form of a disk, under the influence of an air current, from the state to the natural limit of dough extension, where a break occurs. By recording a curve on a recording cylinder, it is possible to assess the flour’s baking properties [17] .
● Analysis of dough behavior
Add 2.5% salted water to 250 g flour. Knead the mixture (flour + water) for 2 minutes. Knead the resulting dough in the Chopin alveograph mixer (8 min, 60 rpm). Roll the dough back and forth on a glass plate using a roller. Lubricate dough with kerosene oil. Using a cookie cutter, cut the rolled dough into 5 pieces. Let dough pieces rest for 14 min, 25˚C in the alveograph relaxation chamber. Insert each dough piece between two metal plates to allow the open air valve to apply atmospheric pressure to the dough. Determine the paleographic parameters, notably the dough’s toughness (P), extensibility (L), work of deformation (W) and balance between toughness and extensibility (P/L).
● The energy value was determined using Coleman’s empirical formula and the coefficients of Alwater and Rosa [2] as follows:
E (calories) = 4(% Protein + % Carbohydrate) + (9 × % Lipids).
2.2.6. Statistical Analysis
Analyses are performed in triplicate and results are expressed on a dry matter basis. The data were then subjected to an analysis of variance (ANOVA) using StastSoft software (Tulsa, USA) to compare the means. In the event of a significant difference, the Newman-Keuls test was used to identify the means responsible for the observed difference at the 5% threshold.
3. Results
In this study, the provenance of the samples, schema of composite flour formulations, the formulation of composite flours based on cereals (fonio, sorghum and millet) and gluten in proportions of 90:10%, the composition and physicochemical properties of local cereal flours before gluten insertion and flours after gluten insertion (gluten/local flours composites) are shown in the tables (Tables 1-4) flour preparation process in Diagram 1, the different flours obtained and the commercial gluten used are shown in Figure 1). This formulation gave us the following results: Proteins (fonio, millet and sorghum) from 1.1 to 0.2; 0.4 to 0; and 9.5 to 16.1 g%g respectively. Lipids from 7.2 to 14.01; from 7.1 to 13.9 and from 2.6 to 1.2 g%g. Carbohydrates from 71.6 to 65.5, 7.1 to 13.9, and from 66.2 to 54.6 g%g. Fiber from 2.6 to 2.0 g%g; from 2.7 to 1.9 and from 2.4 to 1.7 g%g respectively. Ash from 2.6 to 1.7; 2.8 to 2.1; and 3.1 to 2.2 g%g. Calories from 325.1 to 292.8; from 322.8 to 287.3; and from 326.2 to 280.7 Kcal. However, the values found: characteristics of pasta made from composite bread-making cereal flours, water and oil absorption capacity, the breads obtained and their characteristics, bread made from local cereal flours are shown in the tables and figure (Tables 5-7 and Figure 2).
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Table 3. Composition of cereal flours before gluten insertion.
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Table 4. Composite gluten and local cereal flours after gluten insertion.
(Fo + Gl): fonio mixtures with gluten; millet with gluten (Mi + Gl) and sorghum with gluten (So + Gl).
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Table 5. Characteristics of composite cereal bread flour pastes.
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Table 6. Water and oil absorption capacity.
CAE: water absorption capacity; CAH: oil absorption capacity.
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Table 7. Bread characteristics of local cereal flours.
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Figure 1. Showing flour of: millet, fonio, sorghum and wheat gluten.
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Figure 2. Showing the three breads made from the flours of: millet, fonio, sorghum and wheat gluten.
The effect of adding gluten flour to cereal flours showed changes in paleographic parameters. At 10% insertion, led to different formulations with the following values (Table 8).
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Table 8. Rheological characteristics.
F1, F2 and F3 are the different formulations.
4. Discussion
Adding gluten flour to local cereal flours increases the total protein, lipid, fiber ash and energy content of composite flours. Protein contents before and after insertion vary from 7.2 to 14.25 g%g for fonio; from 7.1 to 14.36 for millet and from 9.5 to 15.35 g%g for sorghum. These protein contents for the millet and sorghum varieties used are higher than the millet and sorghum varieties used by [19] , which are: 8 to 11.7 and 9.6 to 12.5 g%g respectively. Lipids from 1.1 to 0.7 g%g for fonio; from 0.4 to 0.3 for millet and from 2.6 to 2.3 g%g for sorghum. This protein content in the sorghum variety used in this formulation is higher than that used by [2] [12] , which varies between 12.5%, 11% and 10.5% respectively. Carbohydrates from 71.6 to 71.6 for fonio, from 72.7 to 72.7 for millet and from 2.5 to 2.3 g%g for sorghum; fiber from 2.4 to 2.4 g%g for fonio, from 2.7 to 2.3 g%g for millet and from 2.5 to 2.3 g%g for sorghum; ash from 2. 6 to 2.2 g%g for fonio, 2.8 to 2.2 g%g for millet and 3.1 to 2.2 g%g for sorghum; calories: 325.1 to 92.14 Kcal%g for fonio; 322.8 to 88.54 Kcal for millet and 326.2 to 280. 120.1 Kcal for sorghum. This is probably due to the low carbohydrate and lipid content of gluten. However, the mineral elements in local cereal flours and composite flours. This is higher than in composite flours with a mass difference of 5.0, 1.1, 0.02, and 0.02 calcium, iron, copper and zinc respectively (Table 3 and Table 4). Vitamin contents in local cereal flours and their composites also vary with the insertion of gluten: β-carotene 25 to 27 mg%g; 40 to 43 mg%g and 31 to 35 mg%g respectively. However, the other vitamins—thiamine, riboflavin and niacin—are present, albeit at low levels. According to [20] , traditional hulling by friction, for example, to obtain cereal grains, can influence the content of certain nutrients such as iron by 10% to 12%. These protein and fiber contents in millet are higher than those found by [21] in the preparation of its infant flour formulated with local ingredients. The results obtained showed that mineral contents were as follows: Ca: 105; 92 and 121 mg%g; Mg: 85; 113 and 88 mg%g; Iron: 4.6; 3.7; and 4.8 mg%g; Cu: 0.02; 0.01; and 0.02 mg%g; Zinc: 0.03; 0.04 and 0.04 mg%g respectively.
● Functional properties of composite flours
The dough characteristics of composite flours bread-making cereals (Table 5) show a protein growth rate, and extensibility. The swelling index of (Fo + Gl) is significantly lower than that of the other formulated flours. Toughness and ratio of configuration of the three different formulations increase progressively, but with an average difference of 0.03 to 0.05 (Table 5). However, the bakery strength (F1) value (Fo + Gl) is higher than the others. However, all three values are appreciable, as they are greater than or equal to 150 as the limit value for bread-making [22] . The water absorption capacities of local fonio, millet and sorghum flours are respectively 180.29% for fonio flour, 115.62% for millet flour and 121.54% for sorghum flour. With regard to oil absorption capacity, their values are 104.38% for fonio flour, 95.53% for millet flour and 98.30% for sorghum flour (Table 6). Table 7 shows the characteristics of bread made from local cereal flours and wheat gluten. We note an increase in bread weight after: 2 to 3 hours of fermentation: 538 to 531 and 388 to 352 for (Fo + Gl) and (Mil + Gl). This is probably due to the escape of air from the bread. However, this value decreases for the (So + Gl) mixture to 540 to 533. Also, bread volume increases after: 2 to 3 hours of fermentation for all combinations (Fo + Gl); (Mil + Gl) and (So + Gl). Baker’s strength (W) is the deformability of the dough made by a flour. It is characterized by two parameters: elasticity and extensibility. The first is the dough’s capacity to stretch and return to its original shape after an applied effort, while the second expresses its ability to be stretched without being torn. In terms of rheological characteristics, the baking strength values of formulated flours are given in Table 8. These values oscillate around 150 (G + Mi (F2); 155 (G + So) (F3) and 160 (G + Fo) (F1). These values are higher than 150, as a value below 150 is not suitable for bread-making [22] [23] . With regard to the extensibility of formulated flours, we note a slight difference of 0.8 to 1.8 mm with the highest value (G + So) (F3) at: 77.6. Toughness P and the P/L ratio increased with the insertion rate. The F3 formulation had the highest values for toughness and extensibility, at: 77.6 and 135 mm. Baking strength was highest with F1 (G + Fo), followed by F2 and F3 respectively. The swelling index is higher with F3 than the other two. An excellent study was made by [12] in a process for formulating composite flour (sorghum and wheat flours) with different incorporations: water absorption capacity 58%; tenacity 110%; extensibility 70%; with good bolting strength (W) 260% versus 121.54%; 135%; 77.6% and 155% respectively (Table 6 and Table 8). This difference can probably be linked to the following parameters: variety, chemical composition of the growing medium (soil). According to [23] , between 150 and 180 is the average for bread-making. For an extension, we carried out a chemical study to determine the lipid, carbohydrate, trace element and vitamin contents before and after formulation for all the flours formulated, including sorghum flour and gluten (So + Gl) (Table 3 and Table 4), and the bread characteristics of the flours.
5. Conclusion
Cereals (fonio, sorghum and millet) are widely used for human consumption in many countries in Africa and elsewhere. For economic and health reasons, a formulation of cereal-based flours was developed in this work as a method of preparing flour for bread-making with the incorporation of gluten flour in local cereal flours (fonio, sorghum and millet) up to 10%, which will reduce wheat flour imports by at least 50%. In addition, the production of low-cost ready-to-use therapeutic foods (breads, cakes and gluten flour, cookies) based on composite flours made from local cereal flours will considerably reduce malnutrition among children under five. To this end, post-formulation studies were carried out to assess the nutritional quality of the composite flours (dry matter, protein, lipid, carbohydrate, ash and micronutrient contents), as well as their functional properties (water and oil absorption capacity) and baking value. The flours formulated had an appreciable baking strength of 150 Joule. Further studies are recommended, as these flours could be an alternative to make up for the shortfall in imported flours.