Evaluation of proximate composition, and mineral content of five soybean varieties in two research centers

doi:10.21203/rs.3.rs-5273018/v1

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Evaluation of proximate composition, and mineral content of five soybean varieties in two research centers

https://doi.org/10.21203/rs.3.rs-5273018/v1

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Soybean is a valuable source of high-quality protein and oil, widely used in human diets. This study aimed to evaluate the proximate composition and mineral content of soybean varieties from two Ethiopian research centers and Dolo-Ado. Mature soybean seeds were collected from Kelafo, Dolo-Ado, and local markets. Proximate composition (moisture, ash, fat, protein, fiber) and mineral content (calcium, iron, magnesium, zinc) were analyzed using standard methods, with triplicate measurements. Data were analyzed using Design Expert version 13 and Excel 2019. Moisture content ranged from 4.78–7.34%, protein 19.65–30.35%, fat 5.37–21.61%, and fiber 3.75–6.29%. Calcium ranged from 48.9–157.2 mg/100g, iron 5.37–12.06 mg/100g, magnesium 658.5–2429.1 mg/100g, and zinc 3.79–6.45 mg/100g. Varieties K-Pawa 1, K-Pawa 3, D-Pawa 3, and D-Gezale exhibited high nutritional value, making them suitable for addressing protein-energy malnutrition and mineral deficiencies, particularly in vulnerable populations such as infants and lactating mothers.

Food Science & Technology

Soybean varieties

Proximate composition

Mineral content

Nutritional analysis

Soybean, botanically known as Glycine max (L.), originated in Eastern Asia, likely in northern and central China. Mature soybean seeds consist of approximately 40% protein, 20% oil, and 10% water-soluble carbohydrates [1]. Glycine max is a vital legume that is increasingly consumed for its nutritional and economic benefits [2]. Its high-quality protein and oil are essential for human health. As one of the primary sources of these nutrients, soybeans play a significant role in human diets [3]. The quality of soybeans is typically assessed based on their protein, oil, fatty acid, and mineral content, making these factors crucial for enhancing human and animal nutrition. This importance is likely because soybean products are excellent and affordable sources of protein, minerals, phosphorus, and vitamins [4]. Additionally, soybean products are well-known for their significant contributions to health and wellness. Regular soybean consumption has been reported to prevent conditions such as heart disease, obesity, hypercholesterolemia, cancer, diabetes, kidney disease, and osteoporosis. Soybeans are also suitable for individuals who experience allergic reactions to animal milk [5]. Among cereals and legumes, Glycine max boasts the highest protein content (40%). In comparison, other legumes contain 20–30% protein, while cereals have a protein range of 8–15% [6].

Soybeans have a higher protein content (40%) compared to beef (19%), chicken (20%), fish (18%), and groundnut (23%), making them a more economical source of protein (IITA 1990). Additionally, soybeans are of particular interest as a plant-based protein due to their cholesterol-lowering effects in patients with type II hyperlipoproteinemia [7]. Besides their high protein content, soybeans contain approximately 20% oil, the second-highest among all food legumes. Peanuts have the highest oil content at about 48% on a dry matter basis, followed by chickpeas with around 5% oil [8]. Soybeans are also rich in essential minerals and vitamins such as iron, zinc, copper, thiamine, riboflavin, niacin, pantothenic acid, and phospholipids [9]. These vitamins and minerals play crucial roles in red blood cell formation due to their hematinic properties [10]. Moreover, soybeans are known to contain flavonoids, particularly isoflavones, which contribute to their strong cancer-fighting and disease-preventing properties [11].

As part of the study evaluation of the proximate composition and mineral content of five soybean varieties in two research centers, various research centers under the Somali Region Pastoral and Agro-pastoral Research Institute (SoRPARI) have focused on developing and releasing soybean varieties. A proximate analysis is essential to assess the quality of these varieties. This study aims to evaluate the nutritional value, anti-nutritional factors, mineral content, and functional and physical properties of soybean varieties adapted and released by SoRPARI. Understanding the nutritional diversity of soybeans will have a direct impact on improving their quality for breeding and food product development, addressing food insecurity, malnutrition, and mineral deficiencies, particularly in low-income communities. The objective of the study is to evaluate the proximate composition and mineral content of the five soybean varieties.

2.1. Sample collection and preparation

Mature soybean seeds were obtained from the Kelafo and Dolo-Ado Research Centers, while two local varieties were purchased from local markets in Gode and Jigjiga cities, located in the Somali Regional State, Ethiopia. The seeds were first cleaned to remove any foreign materials, and any damaged or insect-infested seeds were discarded. After being washed with tap water, the seeds were sun-dried for 8 hours to eliminate any moisture absorbed during washing. They were then milled into flour, packed in airtight polyethylene bags, and stored at 4°C for further analysis.

2.2. Determination of Proximate Composition

The proximate composition of the soybean varieties was determined using standard analytical methods [12]. All measurements were performed in triplicate, and the results were expressed as percentages.

2.3. Determination of Mineral content

The concentrations of selected mineral elements (Ca, Fe, Mg, and Zn) were determined from a solution prepared by wet digestion of the sample ash with a 1:1 (v/v) mixture of HCl and nitric acid. The analysis was conducted using an atomic absorption spectrophotometer [12].

2.4. Data analysis

All analyses were performed in triplicate and the results were presented as mean ± standard error. Data analysis and modeling were conducted using GenStat version 18 and Excel 2019. A significance level of p < 0.05 was considered statistically significant.

3.1. Proximate composition of soybean varieties

The soybean varieties were analyzed for various proximate compositions, including ash content, moisture content, crude fat, crude fiber, crude protein, carbohydrate content, and energy content, using standard techniques. The results are summarized in Table 1. Variety K-Pawa 1 had the highest moisture content among all the varieties, although it was not significantly different from K-Pawa 2. The lowest moisture content was found in L-Jigjiga, which showed a significant difference compared to L-Gode. D-Pawa 1 exhibited the highest ash content, although there was no significant difference between it and the other varieties, except for K-Gezale and the local varieties.

Table 1 also shows that D-Gezale had the highest crude fat content, though K-Pawa 3 showed no significant difference from G-Gezale. The local varieties, however, had the lowest crude fat content. The data further revealed that the local varieties contained more fiber than the others. Notably, D-Pawa 3 had the highest protein content, while the local varieties had the lowest. Carbohydrate content was found to be higher in the local varieties, with significant differences observed between them. K-Pawa 1 had the lowest carbohydrate content. In terms of energy content, D-Gezale recorded the highest significant value, with no significant differences between varieties D-Pawa 1, D-Pawa 2, K-Gizo, K-Pawa 1, K-Pawa 2, and K-Pawa 3.

Table 1

Proximate Composition of Different Soybean Varieties
Varieties	Location	Parameters
Varieties	Location	Moisture (%)	Ash (%)	Crude Fat (%)	Crude Protein (%)	Crude Fiber (%)	Carbohydrate (%)	Energy (%)
Gezale	Dolo-ado Center	5.09 ± 0.04^c	5.62 ± 0.07^ab	21.61 ± 0.03^a	28.92 ± 0.03^c	3.75 ± 0.13^d	35.01 ± 0.18^ef	450.21 ± 0.32^a
Gizo		5.51 ± 0.02^abc	5.76 ± 0.03^ab	13.04 ± 0.02^h	28.68 ± 0.03^d	5.04 ± 0.03^b	41.97 ± 0.04^c	399.96 ± 0.23^e
Pawa 1		5.53 ± 0.03^abc	6.30 ± 0.48^a	21.47 ± 0.01^b	28.73 ± 0.02^d	4.45 ± 0.09^bc	45.35 ± 0.05^efg	489.5 ± 0.39^b
Pawa 2		5.17 ± 0.01^bc	5.75 ± 0.19^ab	20.83 ± 0.01^e	27.96 ± 0.02^f	4.14 ± 0.05^cd	47.07 ± 0.00^d	487.6 ± 0.26^b
Pawa 3		5.81 ± 0.11^abc	5.77 ± 0.08^ab	20.02 ± 0.00^f	30.35 ± 0.02^a	4.57 ± 0.05^bc	45.06 ± 0.52^fg	481.8 ± 2.00^c
Gezale	Kelafo Center	6.25 ± 0.02^abc	5.22 ± 0.07^b	16.56 ± 0.01^g	26.35 ± 03^g	4.32 ± 0.24^bcd	52.77 ± 0.22^c	465.6 ± 0.88^d
Gizo		6.52 ± 1.68^abc	5.34 ± 0.09^ab	21.27 ± 0.00^c	26.35 ± 0.03^g	4.92 ± 0.30^b	35.60 ± 0.32^d	439.23 ± 1.26^b
Pawa-1		7.34 ± 0.61^a	5.64 ± 0.55^ab	21.13 ± 0.05^d	29.52 ± 0.02^b	4.62 ± 0.02^bc	44.73 ± 0.06^g	487.2 ± 0.17^b
Pawa-2		7.17 ± 0.42^a	5.84 ± 0.50^ab	21.12 ± 0.00^d	28.49 ± 0.01^e	4.36 ± 0.20^bcd	46.03 ± 0.01^e	488.2 ± 0.09^b
Pawa-3		7.12 ± 0.02^ab	5.61 ± 0.27^ab	21.60 ± 0.00^a	27.94 ± 0.02^f	4.63 ± 0.03^bc	31.1 ± 0.00^e	430.56 ± 0.08^b
Cantrol	Gode	4.79 ± 0.70^c	4.27 ± 0.38^c	5.37 ± 0.02^j	19.86 ± 0.02^h	5.94 ± 0.30^a	59.77 ± 0.29^a	366.85 ± 1.32^f
Control	Jigjiga	4.78 ± 0.08^c	3.82 ± 0.12^c	6.34 ± 0.02ⁱ	19.65 ± 0.04ⁱ	6.29 ± 0.08^a	59.12 ± 0.02^b	372.14 ± 0.43^g
Grand Mean		6.59	5.43	17.53	26.9	4.75	50.82	468.64
CV %		11.6	7.8	0.2	0.1	6.2	0.6	0.3
LSD %		1.66	0.658	0.071	0.076	0.644	0.664	2.63
All values are the means expressed on a dry matter basis ± standard error. Means with the same superscripts do not differ significantly (P < 0.05), D = Dolo-Ado, K = Kelafo, CV = Coefficient of Variation, LSD = Least Significance Difference.

3.2. Mineral contents and anti-nutritional factors of different soybean varieties

The results of the mineral element analysis, including calcium, iron, magnesium, and zinc, are shown in Table 2, with concentrations expressed as mg/100 g of soybean flour. Variety K-Pawa 3 had the highest calcium content, followed by D-Pawa 3 and D-Gizo, though there was no significant difference between D-Pawa 3 and D-Gizo. K-Pawa 3 also had the highest iron content among all the varieties, while the local varieties showed the lowest mineral content overall.

In terms of magnesium, K-Pawa 2 exhibited the highest content, with K-Pawa 3 ranking next. The results indicate that K-Pawa 3 had significantly higher levels of all the analyzed minerals compared to the other varieties. The lowest zinc content was found in L-Jigjiga.

Table 2

Total mineral contents of different soybean varieties
Varieties	Location	Parameters (mg/100 g)
Varieties	Location	Calcium %	Iron %	Magnesium %	Zinc %
Gezale	Dolo-ado Center	130.8 ± 0.19^d	9.570 ± 36.07^bcd	930.9 ± 36.07^e	6.040 ± 0.01^abc
Gizo		143.0 ± 2.10^b	9.765 ± 111.75^bcd	1144.1 ± 111.75^cd	6.030 ± 0.09^abc
Pawa 1		137.9 ± 1.47^c	8.105 ± 67.80^de	1073.5 ± 67.80^cde	6.000 ± 0.10^abc
Pawa 2		135.4 ± 1.57^c	9.990 ± 2.87^bc	1231.8 ± 2.86^bc	6.075 ± 0.19^abc
Pawa 3		143.7 ± 1.32^b	10.815 ± 16.23^ab	1140.0±`6.23^cd	5.680 ± 0.19^cd
Gezale	Kelafo Center	137.9 ± 1.34^c	9.165 ± 11.90^bcde	978.1 ± 11.90d^e	6.450 ± 0.00^a
Gizo		138.1 ± 1.21^c	9.355 ± 0.13^bcde	1117.3 ± 0.13cd^e	6.275 ± 0.30a^b
Pawa-1		130.2 ± 0.81^d	8.715 ± 61.65^cde	1095.1 ± 61.64^cde	6.385 ± 0.03^ab
Pawa-2		127.1 ± 1.74^d	8.110 ± 1.07^de	2429.1 ± 1.07^a	6.120 ± 0.07^abc
Pawa-3		157.2 ± 0.74^a	12.060 ± 9.51^a	1378.2 ± 9.51^b	5.960 ± 0.08^bc
Cantrol	Gode	55.4 ± 1.10^e	7.705 ± 1.20^e	658.5 ± 1.12^f	5.275 ± 0.03^d
Control	Jigjiga	48.9 ± 1.38^f	5.375 ± 123.48^f	945.3 ± 123.48^e	3.790 ± 0.16^e
Grand Mean		123.79	9.06	1177.0	5.840
CV %		7.6	6.8	3.3	8.1
LSD %		1.49	173.3	0.41	0.19
All values are the means expressed on a dry matter basis ± standard error. Means with the same superscripts do not differ significantly (P < 0.05), D = Dolo-Ado, K = Kelafo, CV = Coefficient of Variation, LSD = Least Significance Difference.

4.1. Proximate composition of Soybean

The study revealed that soybean has a low moisture content, ranging from 4.78–7.34%. This low moisture content implies that soybeans can be stored for extended periods, as moisture facilitates the growth of microorganisms. These findings align with a similar study conducted in Nigeria, which reported a moisture content of 6.12%, further supporting the idea that soybeans can be stored for long periods without significant microbial growth [13].

The ash content in the soybean samples was significantly high, ranging from 3.82–6.30%, suggesting that these soybeans are rich in minerals. This finding is consistent with another study in Nigeria, which reported an ash content of 4.29%, indicating the potential of soybeans as a valuable source of minerals [14].

The protein content in the soybean samples ranged from 19.65–30.35%, indicating a high concentration of protein compounds. This makes soybeans a promising solution for addressing malnutrition, particularly protein-energy malnutrition conditions like marasmus and kwashiorkor.

The crude fat content in this study ranged from 5.37–21.61%, with varieties such as D-Gezale and K-Pawa 1 showing the highest values at 21.61% and 21.60%, respectively. Though the overall fat content was lower compared to other sources, these varieties demonstrated promising results, which are in agreement with previous studies [14].

The fiber content of the soybean samples ranged from 3.75% (D-Gezale) to 6.29% (L-Jigjiga). Fiber is known for its health benefits, including preventing constipation and reducing the risk of colon cancer. This finding is consistent with another study that reported a fiber content of 6.84% [2].

The carbohydrate content ranged from 44.75–68.82%, offering a high carbohydrate level that can be valuable in managing protein-energy malnutrition. High carbohydrate content allows the body to use proteins, fats, and minerals for tissue building and repair rather than as an energy source. These results are consistent with those of a previous study that reported carbohydrate content between 34.97% and 39.86% [15].

Finally, the energy content of the soybeans ranged from 403.1 kcal/100 g to 450.21 kcal/100 g, aligning with research conducted in Ghana, where the energy content ranged from 458.58 to 473.62 kcal/100 g [15]. These results indicate that soybeans can provide significant energy, making them a valuable food source.

4.2. Mineral Concentrations of Soybean

The study found that calcium content in the soybean varieties ranged from 48.9–157.21%. These results suggest that soybeans can be utilized in the development of various products, such as complementary foods for infants, as calcium plays a crucial role in building strong bones and teeth. Calcium is a key component of bone and tooth formation, which aligns with the findings of [15], who also emphasized calcium's importance in skeletal development.

The iron content in the soybeans was significantly high, ranging between 5.37% and 12.06%, with K-Pawa 3 showing the highest iron concentration. This makes soybeans a valuable resource for addressing iron deficiency, particularly in vulnerable groups such as lactating mothers, young children, and adolescent girls. This finding agrees with [16], which highlighted iron's essential role in red blood cell function, particularly in carrying and releasing oxygen throughout the body.

Magnesium content was also significantly high, and it plays a vital role in enabling protein formation, supporting calcium retention in teeth, and aiding in energy release. The zinc content in the soybeans ranged from 3.79–6.45%, with zinc providing numerous health benefits, including enhancing the immune system’s ability to fight off bacteria and viruses. These results are consistent with research that shows magnesium supports protein synthesis and energy metabolism, while zinc is crucial for immune function [15].

The results of this study indicate that the soybean varieties grown in the Kelafo and Dolo-Ado centers show promising potential. Among the key findings, varieties such as K-Pawa 1, K-Pawa 3, D-Pawa 3, and D-Gezale exhibited high levels of protein, crude fat, and carbohydrates. These varieties serve as valuable sources of macronutrients, making them suitable for the development of various food products and intervention programs aimed at alleviating protein-energy malnutrition.

Although the fiber content was relatively low, it still offers health benefits, such as helping to prevent or relieve constipation and addressing issues like diabetes and obesity. Additionally, the high ash content in some of the soybean varieties suggests they are rich in essential minerals, including magnesium, calcium, zinc, and iron, which are crucial for supporting overall health and development.

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 acknowledge the support of SoRPARI in finishing the study.

Availability of Data and Materials

Not applicable.

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The authors declare no competing interests.

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Evaluation of proximate composition, and mineral content of five soybean varieties in two research centers

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Abstract

1. INTRODUCTION

2. MATERIAL AND METHODS

2.1. Sample collection and preparation

2.2. Determination of Proximate Composition

2.3. Determination of Mineral content

2.4. Data analysis

3. RESULTS

3.1. Proximate composition of soybean varieties

3.2. Mineral contents and anti-nutritional factors of different soybean varieties

4. DISCUSSION

4.1. Proximate composition of Soybean

4.2. Mineral Concentrations of Soybean

5. CONCLUSION

Declarations

Ethics Approval and Consent to Participate

Competing Interests

Funding

Authors' Contributions

Acknowledgment

Availability of Data and Materials

References

Additional Declarations

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