Evaluation of proximate composition and mineral contents of Sorghum Blended with Peanut

doi:10.21203/rs.3.rs-5272919/v1

Improving the nutritional status of infants requires the optimal use of available food resources. This study aimed to develop a product and evaluate its proximate composition and mineral content by blending sorghum with peanuts (SBP) to enhance the nutritional quality of sorghum-based foods. Seven formulations of composite flours were created, consisting of 100% sorghum flour with 0% peanut flour, 92.5% sorghum flour with 7.5% peanut flour, 85% sorghum flour with 15% peanut flour, 77.5% sorghum flour with 22.5% peanut flour, and 70% sorghum flour with 30% peanut flour. The technological properties and nutritional characteristics of these composite flours were determined using AOAC methods. The moisture content of the SBP sample flours ranged from 5.34–6.35%, with the mixture containing 70 grams of sorghum and 30 grams of peanut having the highest moisture content. This finding suggests that increasing the peanut proportion raises the moisture content of the flour. The crude protein content of the SBP samples ranged from 12.53–17.38%, with the highest protein concentration (17.38%) observed in the 70:30 sorghum-to-peanut mixture, indicating its potential as a valuable source of plant-based protein. The crude fat content in the sorghum and peanut flours varied between 4.40% and 15.61%. The total carbohydrate content ranged from 54.08–75.33%, with the highest carbohydrate content observed in the 100% sorghum flour and the lowest in the 70:30 sorghum-to-peanut mixture. The total energy content of the SBP sample flours varied between 388.86 kcal/100g and 423.80 kcal/100g. Based on the results, this study suggests that SBP composite flours can be used as complementary foods, meeting the daily energy requirements for infants aged 6–12 months.

Food Science & Technology

Complementary food for infants

Mineral content

Nutritional improvement

Proximate composition

Sorghum-peanut blend

Food crops continue to be a critical source of human nutrition, providing essential nutrients, proteins, and calories, especially in developing countries. Sorghum (Sorghum bicolor), one of the oldest known cereal grains, ranks fifth globally in production after wheat, rice, maize, and barley (Espitia-Hernández et al., 2022). As a potential source of bioactive compounds, sorghum plays a vital role in human nutrition, particularly for over 750 million people living in the semi-arid tropics of Africa, Asia, and Latin America. Most sorghum producers are small-scale subsistence farmers with limited access to essential agricultural inputs such as fertilizers, improved seeds, water, and credit facilities (Teshome et al, 2021). Major sorghum-producing countries include the United States, Nigeria, Sudan, Mexico, China, India, Ethiopia, Argentina, Burkina Faso, Brazil, and Australia, with Burkina Faso leading in sorghum production and consumption per capita (Dicko et al., 2006).

Sorghum sustains the livelihoods of the rural poor and significantly contributes to household food security and nutrition in these regions. Beyond its role in food security, sorghum also provides income for many households (Tadele, 2019). Nutritionally, sorghum is a rich source of micronutrients (minerals and vitamins) and macronutrients (carbohydrates, proteins, and fats). Despite these benefits, sorghum-based foods are often nutritionally deficient and organoleptically inferior. However, sorghum offers various health benefits, including inhibiting cancer tumor growth, protecting against diabetes and insulin resistance, being gluten-free for people with celiac disease, managing cholesterol levels, and providing a high antioxidant content compared to other grains and fruits. Sorghum may also have therapeutic potential for treating human melanoma.

Peanut (Arachis hypogaea L.) is another crucial food crop, valued as an energy-dense source of plant protein. Peanuts are commonly consumed roasted or processed into various products such as peanut butter, sweets, and cakes (Singh et al., 2021). Additionally, peanuts, also known as groundnuts, are a significant source of vegetable oil and protein. Originating in Central America, peanuts have spread globally and are now cultivated in more than 300 varieties worldwide (Sobowale et al., 2019). Rich in health-benefiting nutrients, peanuts contribute to human health through their high protein content and essential nutrients.

In Ethiopia, sorghum is traditionally processed at the household level using small grain mills. To enhance the nutritional quality of cereal-based traditional diets, the supplementation of sorghum with peanut flour, which is high in protein, has often been recommended. Sorghum and peanuts are easily accessible in the region, making them suitable for nutritional improvement initiatives. Therefore, the aim of this study was to investigate the influence of different sorghum and peanut flour composites on proximate composition and functional characteristics. The composites were then developed into sorghum-peanut blended flour, and their sensory characteristics were evaluated.

2.1. Raw Materials and sample preparation, Blending Ratio based complementary food

The experimental materials were sourced from the local market in Jigjiga city, with approximately 5 kg of sorghum grains and peanuts collected. Sorghum flour was prepared following the method described by Almeida-Dominguez et al. (1993), while peanut flour was prepared using the method developed by Yegrem et al. (2022). The sorghum grains were cleaned and sorted, with small, broken, and immature grains, as well as dust, sand, stones, and other foreign materials, removed. The cleaned sorghum was then washed with tap water, milled using a portable hand machine, packed in airtight polythene bags, and stored at room temperature in a dry, clean area.

This study aimed to determine the optimal ratio of sorghum and peanuts in composite flours for use as complementary foods. A D-optimal mixture design was employed, resulting in a total of seven formulations, with sorghum ranging from 70–100 grams and peanut from 0–30 grams, to set up the experiment.

2.2. Proximate Composition Analysis

The proximate composition of sorghum, peanut flour, and their mixed flours was analyzed using standard methods as outlined by the AOAC (2000). Gross energy was calculated based on the fat, carbohydrate, and protein contents using Atwater's conversion factors: 16.7 KJ/g (4 kcal/g) for protein, 37.4 KJ/g (9 kcal/g) for fat, and 16.7 KJ/g (4 kcal/g) for carbohydrates, with the results expressed in calories (AOAC, 2000). Mineral content analysis followed the AOAC (2000) procedures. All analyses were performed in duplicate, and the results were presented as mean ± standard deviation.

2.3. Data Analysis and Optimization

All analyses were conducted in duplicate (unless otherwise stated) and the results were presented as mean values. The statistical significance of the obtained data was analyzed and modeled using Design Expert® version 13. A significance level was accepted at probabilities of p ≤ 0.01 and p ≤ 0.05.

3.1. Proximate composition and energy content of SBP flour

Table 1 indicates the proximate composition of porridge flour from the local ingredients of sorghum and peanuts. The results of the chemical composition analysis of the raw materials of sorghum and peanuts are presented in Table 1. Components other than moisture contents are expressed on a dry basis. There was a significant (P < 0.01) difference between the difference in the values of moisture, protein, fat, ash, fiber, carbohydrate, and energy contents.

Table 1

Proximate composition of SBP flour samples
Std	Run	Block	SBP		Proximate composition
			A:	B:	Proximate composition
			Sorghum (g)	Peanut (g)	M.C (%)	C.P (%)	C.fat (%)	C.Fib (%)	Ash (%)	CHO (%)	Energy (kcal/100g)
7	1	Block 1	70	30	6.35	17.38	14.60	3.61	3.98	54.08	417.27
3	4	Block 1	85	15	5.75	14.70	10.52	2.84	1.98	64.21	410.32
6	3	Block 1	100	0	5.34	12.53	4.40	1.05	1.34	75.33	391.09
2	2	Block 1	70	30	6.23	16.46	15.61	3.53	3.8	54.37	423.80
5	5	Block 1	77.5	22.5	6.09	15.65	12.50	2.97	2.61	60.17	415.83
1	6	Block 1	100	0	5.41	12.43	4.42	1.59	1.32	74.83	388.86
4	7	Block 1	92.5	7.5	5.67	13.66	7.71	2.73	1.45	68.78	399.14

SBP = Sorghum Blended peanut, A = Sorghum, B = Peanut, MC = Moisture Content, CP = Crude Protein, C.Fib = Crude fiber, CHO = Carbohydrate, kcal = kilo calorie.

3.1.1. Moisture content

As indicated in Table 1, the study's findings on the mixture proportion of sorghum and peanut flour demonstrated a strong linear significance at a 1% probability level (P ≤ 0.01) regarding the moisture content of SBP (sorghum blended with peanut) flour. The moisture content of the SBP sample flour ranged from 5.34–6.35%. Notably, the mixture proportion of 70 grams of sorghum and 30 grams of peanut had the highest moisture content among the other ratios. This suggests that increasing the peanut ratio in the mixture elevates the moisture content.

According to the FAO/WHO recommendation for the safety limit on microbial prevention in soft products like porridge, the results indicate that the SBP product, with a maximum moisture content of 6.35%, falls well below the recommended safe limit of 10%, which is considered safe for microbial control. Foods with higher moisture content, as noted by Karuppuchamy et al. (2024), can promote microbial growth, making this result significant for food safety.

In local feeding practices in developing countries, it is common for mothers to prepare large batches of dry infant foods to save time and energy for other household tasks, which makes moisture control vital (Makinde & Lapido, 2012). The regression model for moisture, as indicated in the quadratic model (Eq. 20), illustrates the relationship between the two variables in this study.

$$\:\text{Y}={5.39}_{{\text{x}}_{1}}+{6.29}_{{\text{x}}_{2}}-{0.05}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.1$$

Where Y = Moisture content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

3.1.2. Protein contents

Table 1 shows that the linear mixture of sorghum enriched with peanut flour had a significant effect on the protein content of SBP (sorghum blended with peanut) sample flours, with a strong linear significance (P ≤ 0.01). The crude protein content of the SBP samples ranged from 12.53–17.38%. The highest protein content (17.38%) was observed in the mixture of 70 grams of sorghum and 30 grams of peanut flour, indicating its potential as a good plant protein source. These protein levels align with Teshome (2014), which reported non-extruded protein content ranging between 11.17% and 16.38%. As depicted in Fig. 6, the curve indicates that increasing the peanut ratio results in higher protein content, while decreasing the peanut ratio lowers the protein concentration.

A minimum protein content of 13.8% is required for optimal amino acid complementation and growth in complementary foods. Therefore, all formulations with a protein value of 13.8% or higher met the protein requirements for complementary foods for older infants and young children, as per Masters et al. (2016). The regression model for crude protein content is represented by Eq. 21, demonstrating a quadratic relationship with two variables.

$$\:\text{Y}={12.50}_{{\text{x}}_{1}}+{16.89}_{{\text{x}}_{2}}-{0.11}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.2$$

Where Y = Protein content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

3.1.3. Protein contents

Table 1 indicates that the linear mixture of sorghum and peanut flour has a significant effect on the crude fat content of the SBP sample flours, with a strong linear significance (P ≤ 0.01). The crude fat content of the SBP samples ranged between 4.40% and 15.61%. These results align with the study by Teshome (2014), which recorded fat content in extruded blends of sorghum-peanut, sorghum-soybean, and local control samples, ranging from 7.3–18.36%, 4.42–10.5%, and 1.25% for extruded sorghum-peanut, sorghum-soybean, and control samples, respectively.

Similar findings were also reported by Shimelis & Rakshit (2005). Conversely, Makinde & Lapido (2012) recorded a higher crude fat content (4.12%) in sorghum flour. These variations could be attributed to differences in variety or processing methods. The regression model for crude fat content is represented by Eq. 22, showing a quadratic relationship with two variables.

$$\:\text{Y}={4.46}_{{\text{x}}_{1}}+{15.03}_{{\text{x}}_{2}}+{2.48}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.3$$

Where Y = Crude fat content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

3.1.4. Crude fiber contents

Table 1 demonstrates that the linear mixture of sorghum and peanut flour significantly influences the crude fiber content of the SBP sample flours, with a strong linear significance (P ≤ 0.01). The fiber content of the SBP samples varied among the seven different formulations, ranging from 1.05–3.61%. A statistically significant difference (P ≤ 0.01) was observed among the different composite SBP sample flours. The highest fiber content was noted in SBP samples prepared with a mixture of 70 grams of sorghum and 30 grams of peanut flour.

The results further indicated an increasing trend in fiber content correlating with a higher proportion of peanut flour. This finding is consistent with Teshome (2014), where the fiber content was reported to range from 1.31–2.29% for sorghum-peanut blends, 1.28–2.18% for sorghum-soybean blends, and 2.28% for control samples. According to the Protein Advisory Group Recommendations (1972), the acceptable fiber content for weaning foods should not exceed 5%. High fiber content can reduce the digestibility of certain foods; however, the crude fiber contents in the sorghum-peanut blends were within an acceptable range. The fiber content is illustrated in the mixture contour graph (Fig. 8), while the regression model for crude fiber is represented by Eq. 23, indicating a quadratic relationship between the two variables.

$$\:\text{Y}={1.42}_{{\text{x}}_{1}}+{3.48}_{{\text{x}}_{2}}+{1.87}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.4$$

Where Y = Crude fiber content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

3.1.5. Total ash contents

Table 1 indicates that the linear mixture of sorghum and peanut flour significantly affects the total ash content of the SBP sample flours, with a strong linear significance (P ≤ 0.01). The ash content in the SBP blends of sorghum and peanut samples ranged from 1.32–3.98%. This finding aligns with the report by Teshome (2014), which noted that the ash contents of porridge blends from sorghum-peanut, sorghum-soybean, and control samples ranged from 1.33–1.91%, 1.87–3.19%, and 1.10%, respectively.

$$\:\text{Y}={1.42}_{{\text{x}}_{1}}+{3.48}_{{\text{x}}_{2}}+{1.87}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.5$$

Where Y = Total ash content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

The ash content in weaning foods is critical for ensuring adequate mineral intake during infancy. According to the Protein Advisory Group recommendations (1972), the acceptable ash content for such foods should not exceed 5%. In this study, the observed ash content for sorghum aligns with previous research by Makinde and Lapido (2012), which explored the physicochemical properties of sorghum-based complementary foods. Additionally, the formulated foods analyzed in this research consistently remained within this recommended limit, as noted by Munasinghe et al. (2013). The highest recorded ash content in the SBP flour indicates its substantial potential for preparing complementary foods that can effectively meet the mineral requirements for infants during their complementary feeding periods. The regression model for crude fat content, displayed in Eq. 24, further supports the relationship between the variables involved.

3.1.6. Total Carbohydrate content

The findings presented in Table 1 indicate that the linear terms of the mixture of sorghum and peanut flour exhibit a strong significance (P ≤ 0.01) on the total carbohydrate content. The total carbohydrate content for all formulations ranged from 54.08–75.33%. Notably, the formulation with zero peanut flour demonstrated the highest carbohydrate content, while the lowest carbohydrate content was observed in the formulation containing 30 grams of peanut flour.

As the proportion of peanut flour increased, there was a significant reduction in the total carbohydrate content (p < 0.05), which can be attributed to the inherently lower carbohydrate content of peanut flour compared to sorghum. This trend aligns with findings reported by Teshome (2014), indicating that the total carbohydrate content decreases with the inclusion of ingredients like peanuts and soybeans that contain lower carbohydrate levels. According to the Protein Advisory Group (1972), sorghum serves as the primary carbohydrate source, contributing to maintaining approximately 65% of the carbohydrate content in the formulations. The regression model for crude fat content, presented in Eq. 25, indicates a quadratic model with two variables, supporting the analysis of the relationship between the mixture components and their effects on carbohydrate content.

$$\:\text{Y}={74.89}_{{\text{x}}_{1}}+{54.44}_{{\text{x}}_{2}}-{1.38}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.6$$

Where Y = Total Carbohydrate content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

As illustrated in Fig. 10, the graph's curve demonstrates that the carbohydrate content increases as the proportion of peanut flour decreases. The carbohydrate content of sorghum flour obtained in this study was comparable to the 70% reported by Mihrete et al. (2019), although it is lower than the 76.94% reported by Shimelis and Rakshit (2005).

This variation in carbohydrate content may be attributed to factors such as germination time, the specific sorghum variety used, and the differing experimental conditions in each study. These factors can significantly influence the nutritional composition of sorghum flour, leading to variations in carbohydrate content across different research findings.

3.1.7. Total Energy content

As indicated in Table 1, the linear model of the mixture of sorghum and peanut flour demonstrates a strong significance (P ≤ 0.01) concerning gross energy content. The total energy content of the SBP sample flours ranged from 388.86 kcal to 423.80 kcal per 100g. The highest total energy content was observed in the SBP sample prepared from a formula consisting of 70 grams of sorghum and 30 grams of peanut flour, while the lowest energy content was found in the SBP sample made solely from 100 grams of sorghum.

These findings suggest that the high protein and fat content of peanuts significantly contributes to the increased caloric value of the SBP samples when a larger proportion of peanut flour is included. Previous studies on the characteristics of complementary foods have indicated that the high-fat content of legumes and oilseed flours enhances the energy density of products made from various formulations (Nzeagwu et al., 2009). The regression model for total energy content is presented in Eq. 26, indicating a quadratic model with two variables.

$$\:\text{Y}={389.73}_{{\text{x}}_{1}}+{420.60}_{{\text{x}}_{2}}+{16.27}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.8$$

Where Y = Total Energy content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

The current total energy requirement for healthy breastfed infants is approximately 615 kcal/day from 6 to 8 months, 686 kcal/day from 9 to 11 months, and 894 kcal/day from 12 to 23 months (Dewey & Brown, 2003). To meet these energy requirements, infants would need approximately 156 to 237 grams of complementary porridge daily, depending on their age. Incorporating foods rich in lipids into the porridges can enhance energy density and provide essential nutrients (Dewey & Brown, 2003). As indicated in Fig. 11, the curve shows that the energy content of the SBP samples decreases as the peanut ratio decreases.

Table 2

The regression coefficient of a quadratic polynomial, R2, and lack of fit for the proximate composition of SBP flour
Source	MC	C.Protein	C.Fat	C.Fib	C.Ash	ToC	EK	PC	TaC
Model	0.93**	21.67**	126.14**	5.01**	7.82**	387.95**	1670.94**	2162.10**	0.0562**
LM	0.93**	21.66**	125.67**	4.74**	7.22**	386.99**	1666.46**	2161.58**	0.0558**
A	5.39**	12.50**	4.46**	1.42**	1.34	75.23**	391.09**	144.36**	0.4364**
B	6.29**	16.89**	15.03**	3.48**	3.87	56.68**	429.58**	100.52**	0.2137**
AB	-0.05	-0.13	2.48	1.87	-2.79**	-3.54*	7.63	2.61	-0.0713
Adj. R²	0.97	0.97	0.99	0.86	0.9936	0.99	0.98	0.9635	0.9052
Lack of fit	0.45	0.95	0.74	0.28	0.49	0.1113	0.80	0.0928	0.0142
Std.Dev.	0.07	0.34	0.42	0.35	0.0915	0.57	2.52	3.67	0.0308
C.V. %	1.25	2.28	4.17	13.53	3.89	0.87	0.61	2.99	9.66
Mean	5.83	14.69	9.97	2.62	2.35	65.64	411.01	122.67	0.3187
A = Sorghum, B = Peanut, LM = Linear mixture, Std.Dev = standard deviation, MC = Moisture Content, P = Protein, Crude Fib = fiber, ToC = Total carbohydrate, EK = Energy Kcal/100g PC = Phytate contents, TaC = Tannin contents Significant at P ≤ 0.05 level, *Significant at P ≤ 0.01

3.2. Mineral contents of SBP flour

Table 3 displays the mineral composition of all samples and components of the SBP samples. At the 1% probability level (P ≤ 0.01), the models fitted for the mineral content of all samples indicated that the lack-of-fit p-values were not significantly different. Furthermore, a normality plot of the residuals, used as a diagnostic technique, demonstrated that the residuals for all response variables followed a normal distribution.

Table 3

The mineral content of SBP flour samples
Std	Run	Block	SBP				Mineral contents
			A:	B:			Mineral contents
			Sorghum (g)	Peanut (g)	Calcium Mg/100g	Iron Mg/100g		Zinc Mg/100g	Potassium Mg/100g	Magnesium Mg/100g
7	1	Block 1	70	30	59.90	10.07		5.17	585.49	167.10
3	2	Block 1	85	15	23.84	4.16		3.42	441.56	130.43
6	3	Block 1	100	0	5.07	1.99		2.85	320.16	105.87
2	4	Block 1	70	30	58.95	10.95s		5.41	549.95	166.60
5	5	Block 1	77.5	22.5	38.68	7.65		3.91	492.34	148.73
1	6	Block 1	100	0	5.06	1.98		2.72	324.86	103.90
4	7	Block 1	92.5	7.5	10.61	2.54		3.00	397.96	122.07
SBP = Sorghum Blended peanut, A = Sorghum, B = Peanut,

3.2.1. Calcium content

Table 3 shows that the linear model of sorghum blended with peanut flour exhibited a strong linear significance (P ≤ 0.01) and a significant interaction effect (P ≤ 0.01) on calcium content. The calcium content for a mixture of 70 grams of raw sorghum and 30 grams of peanut flour was 59.90 mg/100g, while the lowest calcium content, found in the 100:0 ratio of raw sorghum to peanut flour, was 5.07 mg/100g.

As indicated in Table 3, the control group of the study had the lowest calcium content, and it is well-documented in the literature that sorghum is generally not a good source of calcium. The findings of this study demonstrate that calcium concentration increased sharply with higher peanut ratios. Specifically, the 70:30 ratio of sorghum to peanut flour yielded 59.90 mg/100g of calcium, while the 77.5:22.5 ratio provided 38.68 mg/100g. These results align with the Recommended Dietary Allowance (RDA) for infants, which is set at 270 mg per day for ages 6 to 12 months (Trumbo et al., 2002). The current blended product meets the RDA for this life stage, providing 22.18% of the required intake for the highest blend formulation ratio. The regression model for calcium content is presented in Eq. 27, indicating a quadratic model with two variables.

$$\:\text{Y}={4.89}_{{\text{x}}_{1}}+{59.44}_{{\text{x}}_{2}}-{36.92}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.9$$

Where Y = Calcium content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

3.2.2. Iron content

As shown in Table 3, the linear model of sorghum blended with peanut flour exhibited a strong linear significance (P ≤ 0.01) and a significant interaction effect (P ≤ 0.05) on iron content. The iron content across all formulations ranged from 1.98 mg/100g to 10.95 mg/100g (Table 3). The levels of iron in the product were within the recommended range of 9 mg/1000 kcal for local diets formulated for malnourished children (Golden, 2009). The increased iron content in sorghum enhanced with peanut flour is attributed to the higher proportion of peanut flour used.

The study's findings are consistent with the recommended dietary allowance (RDA) for infants and children, indicating a reasonable alignment with nutritional guidelines. Moreover, this result aligns with other studies; the iron levels in sorghum-based complementary foods observed in this study (5.56–6.21 mg/100g) were comparable to those reported by Mosha et al. (2000).

The iron content in the current study ranged from 3.89 to 21.95 mg/100g, while the RDA for infants aged 6 to 12 months is 11 mg/day and 7 mg/day for children aged 13 to 36 months, respectively. The blended product meets 18.09–99.54% of the RDA for infants aged 6 to 12 months and 28.28–100% for children aged 13 to 36 months, based on lower and higher values, respectively. The regression model for iron content is presented in Eq. 28, indicating a quadratic model with two variables.

$$\:\text{Y}={1.92}_{{\text{x}}_{1}}+{10.63}_{{\text{x}}_{2}}-{7.63}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.10$$

Where Y = Iron content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

3.2.3. Zinc content

As indicated in Table 3, the linear model of sorghum blended with peanut flour showed strong linear significance (P ≤ 0.01) and a significant interaction effect (P ≤ 0.05) on the iron content. The zinc content of sorghum and peanut flour samples is also represented in Table 3. The zinc content of the SBP sample flours ranged from 2.72 to 5.17 mg/100g. This finding aligns with similar reports by Rasmata et al. (2023), which indicated that the zinc content in six formulated sorghum-based complementary foods ranged from 2.01 to 3.7 mg/100g.

According to the findings of this study, the zinc levels are consistent with the recommended dietary allowance (RDA) for infants and children. The RDA for both infants aged 6 to 12 months and children aged 13 to 36 months is 3 mg/day. The blended product meets 90.67–100% of the RDA for both age groups, based on lower and higher values, respectively.

Existing literature suggests that zinc is one of the most essential minerals for infants, as it plays a crucial role in brain growth. As indicated in Fig. 14, the zinc content decreased as the proportion of peanut flour decreased. The regression model for zinc content is presented in Eq. 29, indicating a quadratic model with two variables.

$$\:\text{Y}={2.82}_{{\text{x}}_{1}}+{5.24}_{{\text{x}}_{2}}-{2.79}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.11$$

Where Y = Zinc content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

3.2.4. Potassium content

As seen in Table 3, the linear model of sorghum blended with peanut flour exhibited strong linear significance (P ≤ 0.01). The findings indicate that the SBP sample flours have high potassium concentrations, with the potassium content ranging from 324.86 to 585.49 mg/100g, as shown in Table 3. This finding is promising and meets the recommended dietary allowance (RDA) for infants; however, the potassium requirements for children were not met, which may necessitate further investigation into the blending ratio of peanut flour.

The potassium levels in both products fall within the value of 1400 mg/100 kcal recommended by Golden (2009) for moderately malnourished children. Potassium depletion occurs in all malnourished children, making it essential for supplementary diets to contain sufficient potassium to support a renal excretion rate of 27 mg/kg/day and fecal excretion of 39 mg/kg/day (Golden, 2009).

The results of this study align with the RDA for infants and children. The RDA for infants aged 6 to 12 months is 860 mg/day, while for children aged 13 to 36 months, it is 2000 mg/day (Trumbo et al., 2002). The blended product met 37.23–68.08% of the RDA for infants aged 6 to 12 months and 16.01–29.27% of the RDA for children aged 13 to 36 months, based on lower and higher values, respectively. The regression model for potassium content is presented in Eq. 30, indicating a quadratic model with two variables.

$$\:\text{Y}={325.80}_{{\text{x}}_{1}}+{564.74}_{{\text{x}}_{2}}-{7.34}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.12$$

Where Y = Potassium content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

3.2.5. Magnesium content

Table 3 indicates that the linear model of sorghum blended with peanut flour showed strong linear significance (P ≤ 0.01). The magnesium content of both sorghum and peanut flour samples is represented in Table 3, with the magnesium content of SBP samples ranging from 103.90 to 167.10 mg/100g. This finding aligns with similar reports, and both products met the recommended levels of 200 mg/1000 kcal (Golden, 2009).

Magnesium is an essential nutrient for growth, and its deficiency negatively influences growth by interfering with protein utilization. This mineral is particularly important for stunted children who require adequate magnesium for proper development. The regression model for magnesium content is presented in Eq. 31, indicating a quadratic model with two variables.

$$\:\text{Y}={105.57}_{{\text{x}}_{1}}+{166.58}_{{\text{x}}_{2}}-{12.53}_{{\text{x}}_{1}{\text{x}}_{2}}\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:\dots\:..\text{e}\text{q}.13$$

Where Y = Magnesium content, X₁ = Sorghum, X₂ = Peanut, X₁X₂ = Sorghum and Peanut

Table 4

Regression coefficients of a quadratic polynomial or linear model, R2, and lack of fit for the selective mineral of SBP flour samples
Source	Calcium Mg/100g	Iron Mg/100g	Zinc Mg/100g	Potassium Mg/100g	Magnesium Mg/100g
Model	3452.83**	89.38**	7.24**	64231.38**	4199.20**
Linear mixture	3347.84**	85.24**	6.64**	64227.23**	4187.11**
A	4.89**	1.92**	2.82**	325.80**	105.57**
B	59.44**	10.63**	5.24**	564.74**	166.58**
AB	-36.92**	-7.33*	-2.79*	-7.34	-12.53
Adj. R²	0.9990	0.98	0.9791	0.9769	0.9920
Lack of fit	0.1924	0.45	0.3594	0.6405	0.0919
Std. Dev.	0.7666	0.47	0.1599	15.84	2.37
C.V. %	2.66	8.34	4.23	3.56	1.75
Mean	28.87	5.62	3.78	444.62	134.96
A = Sorghum, B = Peanut, Significant at P ≤ 0.05 level, *Significant at P ≤ 0.01

3.3. Optimum blending ratio of SBP Product

The optimization process involved establishing criteria for each response to determine the optimum levels of the variables in the experiment. The objective was to maximize the puffing scale, rollability scale, crude protein, crude fat, crude fiber, total ash, total carbohydrate, total energy, calcium, iron, zinc, and overall acceptability. This research aimed to identify the ideal blending ratios of each ingredient to produce a porridge with the desired nutritional content and sensory appeal.

The optimized formulation consisted of 74.90 grams of sorghum flour and 25.10 grams of peanut flour. The overall acceptability values for moisture, protein, fat, fiber, ash, carbohydrate, energy, magnesium, calcium, iron, potassium, and zinc were as follows: 16.16%, 13.65%, 6.14%, 3.08%, 3.40%, 57.59%, 417.79 kcal/100g, 154.91 mg/100g, 45.50 mg/100g, 18.85 mg/100g, 525.09 mg/100g, and 4.47 mg/100g, respectively.

Table 5

Response optimization for proximate, physicochemical, and anti-nutritional contents of SBP flour
Name	Unit	Lower Limit	Upper Limit	The optimum value
A: Sorghum	G	70	100	74.90
B: Peanut	G	0	30	25.10
Moisture	%	12.43	17.38	16.16
Protein	%	4.40	15.61	13.65
Fat	%	5.34	6.35	6.14
Fiber	%	1.32	3.98	3.08
Ash	%	1.05	3.61	3.40
Carbohydrate	%	54.08	75.33	57.59
Energy	Kcal/100g	388.86	423.81	417.79
Mg	mg/100g	103.90	167.10	154.91
Ca	mg/100g	5.06	59.90	45.50
Fe	mg/100g	3.99	21.95	18.85
K	mg/100g	320.16	585.49	525.09
Zn	mg/100g	2.72	5.41	4.47
Overall acceptability	Scale	4.501	4.861	4.81
Desirability	--	--	--	0.68

The findings of this study indicated that incorporating a maximum of 30% peanut flour into the composite flour formula significantly enhanced the product's macronutrient profile, including protein, fat, carbohydrate, and energy content. Additionally, the levels of micronutrients such as calcium, iron, zinc, magnesium, and potassium increased dramatically with the addition of peanut flour. As the proportion of peanut flour rose to 30%, the concentration of anti-nutritional factors, such as phytates and tannins, in the SBP product decreased.

To optimize the proximate composition and mineral concentration, the formulation of the SBP sample flours was numerically analyzed. The optimal formulation was found to consist of 74.90% sorghum flour and 25.10% peanut flour, which yielded the best results for all tested parameters.

Ethics Approval and Consent to Participate

This study was conducted in accordance with ethical standards and received approval from the Institutional Review Board at the Somali Region Pastoral and Agropastoral Research Institute. All participants provided written informed consent before their inclusion in the study. The research adhered to ethical guidelines to ensure the confidentiality and rights of the participants.

Consent for Publication

All authors have agreed to the submission and publication of this manuscript. We confirm that the manuscript, including any identifiable information, does not violate any confidentiality agreements and that consent for publication has been obtained from all relevant parties.

Competing Interests

The authors declare that they have no competing interests.

Funding

Somali Region Pastoral and Agropastoral Research Institute

Authors' Contributions

Mahamed Dol Ateye conceived the study, contributed to the study design, performed the analysis, and manuscript writing. Abdulkarim Mohammed Ali, Shamsedin Mahdi Hassan, and Hodo Mohamed Jama contributed data duration and visualization. Mahamed Dol Ateye reviewed and edited the manuscript. All authors read and approved the final manuscript.

Acknowledgment

The authors extend their gratitude to the Somali Region Pastoral and Agropastoral Research Institute for funding this study.

Availability of Data and Materials

Not applicable.

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The authors declare no competing interests.