Nutritional composition, phytochemical, and functional properties of six soybean varieties cultivated in Cameroon

The objective of this study was to evaluate the influence of different varieties on the nutritional composition, phytochemical, and functional properties of selected soybean varieties cultivated in Cameroon. Soybean varieties TGX 1835, TGX 2001‐8DM, MAK SOY 1N, MAK SOY 3N, MAK SOY 4N, and SOUNG PUNGUNG 2400 were collected and analyzed for their nutritional composition (proximate composition and mineral content), oil quality (peroxide, thiobarbituric acid, iodine, and acid values), total phenolic content, and functional properties. Results of the proximate composition showed that soybean varieties MAK SOY 3N, MAK SOY 4N, and TGX 1835 had the highest protein and lipid contents. The calcium and potassium contents were expressively higher in soybean variety MAK SOY 4N. Soybean variety MAK SOY 3N portrayed the best magnesium, zinc, and iron contents. The oils from all the six soybean varieties exhibited very good chemical properties as far as their safety is concerned. TGX 1835, MAK SOY 4N, and SOUNG PUNGUNG 2400 had the highest total phenolic content. The functional properties presented by all six soybean varieties were similar. These new varieties can be exploited for their nutritional and technological properties. The population should be encouraged to produce and consume them.


| INTRODUCTION
Soybean (Glycine max) is one of the most cultivated plants worldwide, mostly grown as a forage crop and oil seed belonging to the family Fabaceae and is regarded as a nutritionally rich food source which has gradually gained vital grounds in functional health foods (Lee et al., 2013).Cultivation of soybean originated from South Asia (i.e., China) and, over time, has spread throughout Asia, America, Africa, and down to Cameroon which is a big part of the Sub-Saharan cultivation system (Onuorah et al., 2010).The cultivation and consumption of soybean in Cameroon dates as far back as 1978 with a recent average annual production rate of 9.23% (Nzossié & Bring, 2020).Legumes like soybean continuously gain solicitation in agriculture and nutrition by both consumers and producers because of its high farm yield, good nutritional composition, and intriguing phytochemical and functional properties (Lopez-Cortez et al., 2016).
Various researches have proven soybean contains about 40% protein (all essential amino acids), 20% fats (largely unsaturated), 30% carbohydrates, 17% fibers (both soluble and insoluble), and 5% ash making it a very good source of minerals such as calcium (276 mg/100 g), magnesium (280 mg/100 g), potassium (1.797 mg/100 g), iron (16 mg/100 g), and zinc (4.8 mg/100 g) (Mateos-Aparicio et al., 2008;Messina, 2016).In addition to the claim of soybean being highly nutritive, it also contains bioactive compounds such as vitamins, phenols, isoflavones, tocopherols, anthocyanins, and tannins which have good antioxidant activity and hence are extremely beneficial for good health (Lee & Choung, 2011;Myung & Hwang, 2008).Although soybean has good nutritional and bioactive properties, it, on the other hand, also contains a significant amount of antinutrients like gums, trypsin inhibitors, oxalate, phytates, saponins, and tannins which reduce the bioavailability of some nutrients thus becoming detrimental to health (Mikic et al., 2009;Sharma et al., 2011).In view of improving the nutritional, bioactive, and functional traits of soybean as well as its agricultural yield, pest resistance, and some physical characteristics, this crop has been genetically modified over the years leading to a surge in the availability of various varieties (Clemente & Cahoon, 2009;Homrich et al., 2012).These varieties are being constantly industrialized and transformed to various solicited products such as oils, soymilk, flours, tofu, cereal blend, and also the bean all with improved nutritional, phytochemical, and functional properties and product quality (Haun et al., 2014;Kim et al., 2021).These varieties may have different nutritional, functional, phytochemical, and organoleptic characteristics.These properties can also be influenced by the environmental and climatic conditions.
In the past decade, a significant dynamic in soybean production in the Sudano-Sahelian region was recorded resulting in a significant increase of the Cameroon's production that rose from 5698 t in 2001 to 24,195 t in 2020 with a growing average annual rate of 9.23%.
Because of its high production, this legume is the second most cultivated oil seed crop in Cameroon after groundnut (Nzossié & Bring, 2020).With the increasing population of Cameroon that rose from about 4.3 million in 1950 to about 27.9 million in 2022, the demand of soybean has significantly increased.This needs to be addressed in order to make this cereal which is the main source of protein (40-42%) (Messina, 2016) for the population in rural areas to be economically and physically available.In this line, it will help reduce the severity of food insecurity in those areas.However, its production yield is influenced by several factors such as environmental and climatic changes (Kim & Choe, 2004;Shan et al., 2005).In this regard, new varieties with specific characteristics are being developed by scientist in order to overcome these challenges and make this interesting source of nutrients available for the entire population.It is important to note that soybean is the world's largest genetically modified crop due to its nutritional, agronomic, and industrial attention (Homrich et al., 2012;ISAAA, 2018).These changes in the gene of the crop made available in the market different soybean varieties with interesting properties.The particularity of genetically modified soybean is that it has superior nutritional traits including changes in protein quality and quantity, essential amino acids, oil, essential fatty acids, bioactives, and mineral elements (Kim et al., 2021).The most common variety available in Cameroon is TGX 1835.Recently, new varieties were made available by the Ministry of Scientific Research to Agricultural Research Institutes so that they can be tested for their production yield.These varieties include TGX 2001-8DM, MAK SOY 1N, MAK SOY 3N, MAK SOY 4N, and SOUNG PUNGUNG 2400.It will be of great importance to know the nutritional, phytochemical, and functional properties of these varieties so as to know the best variety suitable for the production and consumption of Cameroon's population.Variations in varieties have a significant impact on the lipid quality, nutritional composition, and functional and phytochemical properties of soybean.
In previous studies, the impact of the varieties or some genetic changes on the nutritional composition of soybean was reported.Kim et al. (2020) compared the seed nutritional composition between conventional varieties and transgenic soybean overexpressing Physaria FAD3-1.In the same line, Sharma et al. (2014) investigated the physical characteristics and nutritional composition of new soybean genotypes (SL688, SL525, SL783, SL768, SL799, SL794, SL831, and SL869).The chemical composition and nutritional value of some varieties of soybean (Nei dou-4, OAC vision, Severnaya-4, and Sibiryachka) cultivated in Mongolia were investigated by Mungunkhuyag et al. (2021).Mitiku (2021) and Niyibituronsa et al. (2018) evaluated the impact of processing on the nutritional composition of soybean varieties from Ethiopia (Didessa, Katta, and Korme) and Rwanda (Peka 6, Sc.Saga, Sc.Sequel, Sc.Squire, SB24, and Local), respectively.Though several investigations have been carried out on the impact of difference in variety on the nutritional properties of soybean, there is almost no information on the nutritional, phytochemical, and functional properties of the new soybean varieties cultivated in Cameroon.
The objective of this study was to evaluate the influence of difference in varieties on the nutritional composition and phytochemical and functional properties of soybeans cultivated in Cameroon.All chemicals and reagents used in this study were of analytical grade.

| Sample preparation
Soybean samples of different varieties (1 kg each) were taken to the laboratory for sorting, cleaning with tap water to remove dust and other impurities before being dried in the oven at 50 C for 24 h to remove the water that was used for cleaning.After drying, 400 g of each variety was soaked in 3 L of water for 24 h.The soaked samples were de-hulled and dried in an electric air-drying oven at 50 C for 48 h.The dried samples were ground and sieved using a 1 mm diameter pore sieve and were used for further analysis.

| Analysis of proximate composition of different soybean varieties
The analysis of proximate composition was carried out using the Association of Official Analytical Chemists methods (AOAC, 1990).
The moisture content, ash content, crude protein, crude fat, and carbohydrates were evaluated.The moisture content was evaluated by dehydrating the samples in an electric air-dried oven at 103 C till constant weight.For the ash content, the samples were incinerated at 550 C following the AOAC procedure 942.05.The micro-kjeldahl method was used to determine the nitrogen content following the AOAC procedure 984.13 and the protein estimated as nitrogen Â 6.25.The soxhlet method was used for the measurement of the fat content according to the AOAC procedure 963.15.The AOAC (2005) method was used for the determination of the fiber content.The amount of carbohydrates was calculated by difference (AOAC, 1990), after deducting the lipid, moisture, protein, fiber, and ash contents from 100.

| Analysis of mineral content
The ash obtained from the incineration of each sample was dissolved with 10 mL of a 20% HCl solution.The solution was filtered, and the filtrate was used for the detection and quantification of minerals.An atomic absorption spectrometer (Varian 220FS Spectra AA, Les Ulis, France) was used for this purpose and for the following minerals: calcium, sodium, iron, potassium, and magnesium.The vanadomolybdate colorimetric method was used for the determination of the phosphorus content.Calibration curves of standards were used for this purpose.

Oil extraction
Oil from soybean varieties was extracted using the maceration method as reported by Womeni et al. (2013).About 200 g of soybean flour was macerated in 800 mL of hexane.The mixture was regularly stirred for 48 h before being filtrated with the Whatman paper (Number 1).The residues were further macerated in 400 mL of hexane to extract the residual oil.The filtrate was evaporated at 40 C under vacuum on a rotatory evaporator for the removal of hexane.
The oil was weighed for the determination of the extraction yield.

Oil characterization
The collected oil samples were characterized by determining their peroxide, thiobarbituric acid, iodine, and acid values.The peroxide value was determined following the International Dairy Federation (1991) standard method 74A:1991.The iodine and acid values were determined following the AOCS ( 2003) standard method.The thiobarbituric acid value was evaluated following the method described by Draper and Hadley (1990).

Extraction
The phenolic compounds were extracted from soybean flours by maceration in ethanol as reported by Womeni et al. (2013).About 50 g of each soybean flour was macerated at room temperature in 200 mL of ethanol and stirred for 48 h.The solution was filtered using the Whatman paper number 1, and the cake was re-extracted in 100 mL of ethanol to maximize the extraction of phenolic compounds.After mixing both filtrates, they were evaporated at 40 C under vacuum for the removal of ethanol.The dried extract was weighed, and the yield was calculated.It was therefore stored in the freezer for further analysis.

Analysis of the total phenolic content
The method reported by Gao et al. (2000) was used for the determination of the total phenolic content of soybean flour samples.In this light, 20 μL of a 2 mg/mL extract solution was added into a 5 mL test tube.After that, 0.2 mL of Folin-Ciocalteu reagent and 2 mL of distilled water were added.The mixture was allowed to incubate for 3 min at room temperature, and 1 mL of a 20% sodium carbonate solution was added.The solution was again incubated for 20 min under similar conditions, and the absorbance of the final solution was measured at 765 nm on a spectrophotometer.The standard curve of gallic acid was used for the calculation of the total phenolic content, which was expressed in milligrams of gallic acid equivalent per gram.

Water and oil holding capacities
The methods described by Lin et al. (1974) modified by Tambo et al. (2019) were used for the determination of these parameters.About 1 g of soybean flour was mixed with 10 mL of palm olein for the evaluation of the oil holding capacity.The same method was used for the water holding capacity, but in this case, distilled water was used.
The mixture was incubated in a water bath at 30 C for 30 min before being centrifuged at 4,500g for 15 min.The volume of water or oil absorbed was measured.The water and oil holding capacities were determined as follows: where Vi = initial volume of water/oil and Vf = volume of water/oil after centrifugation.

Loose and packed bulk densities
The method reported by Okaka et al. (1991) was used for the determination of these parameters.About 20 g of soybean flour was introduced into a 100 mL measuring cylinder, and the volume occupied by the sample was recorded.After that, the cylinder was tapped 100 times, and the second volume was recorded.These values were used to calculate the loose and packed bulk densities using the formula: Loose density, Packed density ¼ Weight of Sample=Volume occupied by the sample:

Hausner ratio and porosity
The Hausner ratio which is the proportion of loose and packed bulk densities was calculated as follows: Hausner ratio ¼ Packed density=Loose density: The following formula was used for the calculation of the porosity, equally from the loose and packed bulk densities: Compressibility index=Porosity ¼ Packed density ð À Loose density=Packed densityÞ Â 100:

Emulsion activity and stability
The emulsion activity and stability were determined according to the method described by Beuchat (1977) and Kinsella (1979), respectively.About 1 g of soybean flour was mixed with 3 mL of distilled water and 3 mL of refined palm olein in graduated centrifuge tubes.The mixture was stirred for 10 min using a vortex and centrifuged at 3500g with a velocity of 2.054 g for 30 min.After this, the emulsion's height was measured.For the emulsion stability, the tube was first heated at 80 C for 30 min before the centrifugation process.The emulsion activity and stability were calculated as follows: where He = height of the emulsified layer in centimeters; Hw = total height of the liquid in the tube in centimeters; Hes = height of the emulsified layer after treatment (in centimeters); and Hws = total height of the liquid in the tube after thermal treatment in centimeters.

pH and titratable acidity
The AOAC (1990) method was used for the measurement of the pH of soybean flour solutions.About 1 g of each sample was introduced into centrifuge tubes and mixed with 10 mL distilled water.The mixture was stirred for 30 min using a vortex and centrifuged at 4500g for 15 min.The pH of the aqueous phase was determined using a calibrated pH meter at room temperature (25 C).
Concerning the titratable acidity, the method reported by AFNOR (1982) was used for the determination of the titratable acidity.About 1 g of sample was soaked in 10 mL of distilled water for 30 min, and the volume of solution was taken to 50 mL.After that, 0.1 mL of phenolphthalein solution (0.05% in ethanol 1/1 (v/v)) was added.The mixture was titrated using a 0.1 N NaOH solution (4 g/L).When a persistent pink color (for at least 30 s) appeared, titration was stopped, and the volume of NaOH used was recorded (V NaOH in milliliters).The titratable acidity was calculated as follows: where ml = ml 0.1 NaOH used; N = normality of 0.1 N NaOH; and m = mass of flour.

Protein solubility
Soybean flour samples were analyzed for their protein solubility as described by Ige et al. (1984).About 1 g of sample was dissolved in 25 mL distilled water, and the pH was adjusted to the desired value using a 1 N HCl/NaOH solution.The pH values of 2, 4, 6, 8, and 12 were considered.The tubes containing the samples were centrifuged at 4000g for 15 min, and protein content was determined using the biuret method (1949).Protein solubility was calculated using the following formula: where M 1 = mass of protein in the supernatant (grams) and M 2 = mass of sample (grams).

| Statistical analysis
The obtained data were subjected to one-way analysis of variance with the Student-Newman-Keuls tests using the software Graphpad-InStat version 3.0.10.0 (Graphpad software), to evaluate the statistical implication of the data.The variances were important at probability level less than 5%.The ash content was found to be ranged between 3.70% and 5.20%, which was higher than 1.01-1.67%reported by Eshun (2012) but close to 5.07-5.89%obtained by Mungunkhuyag et al. (2021) with different soybean varieties.The ash content is an indicative of the amount of minerals present in a sample.The slight variations in the ash content between samples can be attributed to the difference in varieties.

| Proximate composition
The protein content revealed values ranged between 25.50% and 36.62%, which were lower than 39.4-44.4% and 36.94-40.01%,respectively, reported by Eshun (2012) with different soybean varieties.MAK SOY 4N, MAK SOY 3N, and TGX 1835 were found to exhibit the highest (p < 0.05) protein contents compared with the other varieties.The differences observed can be attributed to the cultivar, the production site, and period.High protein content suggests that soybean varieties could be used in the management of protein energy malnutrition such as kwashiorkor and marasmus.It also helps in body building, tissue maintenance, and reparation as well as strengthening the immune system.
The lipid content values ranged between 26.98% and 32.38%, which were higher than 17.7-20.3%and 14.0-18.7%,respectively, reported by Mungunkhuyag et al. (2021) and Sharma et al. (2014) with different soybean varieties and genotype.However, MAK SOY 3N and MAK SOY 4N presented significantly ( p < 0.05) higher lipid contents compared with other varieties.This can be attributed to factors such as the cultivar, environmental factors, the maturity of the plant, and geographical location.Soybean oil is recognized for its high content in polyunsaturated fatty acids among which essential fatty acids (linoleic acid and alpha-linolenic acid) were reported to have cardio protective, anti-obesity, anticancer effects, and so forth (Han, 2012;Messina, 1997).

| Mineral content
The mineral content of different soybean varieties is presented in Looking at the calcium content, its value was ranged between 384.00 and 880.00 mg/100 g, which was higher than 62.93-217.74mg/100 g obtained by Eshun (2012) with soybean varieties Slintuya-1, Quarshie, and Jenguma.The calcium content of the soybean varieties tested varied significantly with the highest value obtained with MAK SOY 4N.The variations obtained among the varieties as well as with those of the literature can be attributed to the plant variety, nature of the soil, environmental factors, geographical location, and the state of maturity of the plant.As previously mentioned with phosphorus, calcium is involved in the building and maintenance of bones and teeth.In addition, calcium plays the role of messenger in signal transduction and is also involved in the process of blood clotting (Mehas & Rodgers, 1997).
MAK SOY 1N, MAK SOY 3N, and SOUNG PUNGUNG 2400 exhibited significantly (p < 0.05) higher magnesium content compared with the other samples.Magnesium is one of the most important cofactors used in metabolic reactions within the human body (Yokota et al., 2007).It is involved in the biosynthesis of protein and energy production and helps to trap calcium in the teeth (Mehas & Rodgers, 1997).This suggests that the consumption of these three soybean varieties will be highly beneficial for humans as far as metabolism is concerned.The magnesium content obtained in this study was significantly higher than 8.39-8.53,1.6-2.0,and 24.98 mg/100 g, respectively, reported by Eshun (2012), Mungunkhuyag et al. (2021), and Uwem et al. (2017).The factors previously mentioned can be responsible for the variations observed.
The variations in sodium and potassium contents revealed that they were ranged between 297.13 and 1657.63 and 74.42 and 117.07 mg/100 g, which were, respectively, higher than 16.05-18.12and 57.18-79.92mg/100 g obtained by Kim et al. (2020) with 13 conventional and transgenic soybean varieties.Apart from MAK SOY 3N that presented significantly ( p < 0.05) lower sodium and potassium contents, all the other varieties showed good concentrations of these parameters.The variety and environmental factors might explain the changes observed between the varieties tested and the data from literature.Sodium is needed in the body in small quantity and helps in the regulation of blood pressure and in the good functioning of muscles and nerves.In the same light, potassium is beneficial for humans due to its direct relationship with hypertension (Etiosa et al., 2018;Kinge et al., 2019).This suggest that the soybean varieties that exhibited higher potassium and sodium content can help after consumption in the regulation of blood pressure and in the maintenance and good functioning of nerves.
Results of the mineral content showed that MAK SOY 3N had the highest ( p < 0.05) iron and zinc contents (31.59 and 107.20 mg/100 g) compared with other varieties.Iron is well known for its role as part of the respiratory pigments (myogloblin, hemoglobin, and several enzymes).Its deficiency can lead to severe anemia (Loumouamou et al., 2010).Zinc strengthens the immune system and is involved in biosynthesis of proteins and nucleic acids, in wound healing, and in the digestion of carbohydrates (Etiosa et al., 2018).The consumption of MAK SOY 3N would be highly beneficial due to these properties.The amount of iron obtained in this study was lower than 106-113 mg/100 g reported by Kim et al. (2020) with 13 soybean varieties.However, the zinc content was close to 28.39-43.18mg/100 g obtained by the same author on the same soybean varieties.The variety might be responsible for the high iron and zinc contents of MAK SOY 3N compared with other varieties.
T A B L E 2 Mineral content of soybean varieties.Note: Data are presented as mean ± SD (n = 2).Values within the same column with different superscript letters (a-f) are significantly ( p < 0.05) different.
The quality parameters of oils extracted from soybean varieties are presented in Table 3.The determination of the peroxide value generally informs on the primary oxidation state of an oil which is characterized by the presence of hydroperoxides (Ozkan et al., 2007), while the thiobarbituric acid value gives an idea of its secondary oxidation state, that is, the decomposition of hydroperoxides into aldehydes (Iqbal & Bhanger, 2007).Results showed hydroperoxide and thiobarbituric acid values of oils extracted from different soybean varieties ranged between 6.11and 15.52 meq O 2 /Kg and 2.00 and 6.38 ppm, respectively.The peroxide values obtained were within the recommended range which is 15 meq O 2 /Kg for crude oils (FAO/WHO, 2009).In the same line, the acid values of these oils were ranged between 0.31% and 1.53% which is lower than 4% recommended by FAO/WHO (2009).It is important to note that this parameter informs on the presence of free fatty acids released from the hydrolysis of triglycerides present in oils, promoted by moisture (Freja et al., 1999).The iodine value which informs on the degree of unsaturation of oil was ranged between 99.27 and 117.30g I 2 /100 g, which was lower than 124-139 g I 2 /100 g recommended by the CODEX STAN (1999).The oil extraction method as well as the technique used to characterize the iodine value might explain the slight variations observed.The samples that exhibited the best quality based on the abovementioned parameters were TGX 1835, TGX 2001-8DM, MAK SOY 1N, MAK SOY 3N, and SOUNG PUNGUNG 2400.However, in a general manner, these oils exhibited good chemical properties as far as their safety is concerned.Those with high iodine values could be more suitable for consumption as their high level of polyunsaturated fatty acids could make them to have interesting biological properties as it has been demonstrated that oils rich in essential fatty acids are cardio protective and have antidiabetic and anti-obesity properties (Desnoyers et al., 2018).3.5 | Functional properties

| Water and oil holding capacities
The interaction between oils and flours is very important in food formulation for flavor maintenance and improving the texture and nutritional value of food (Womeni et al., 2012).The water and oil holding capacities of different soybean varieties are presented in Figure 2. No significant ( p < 0.05) difference was obtained between the oil holding capacities of the soybean variety tested.However, the oil holding capacity of each flour was about 65%.This can be explained by the high hydrophobicity of the protein due to the high presence of hydrophobic amino acids.It has been reported that the capacity of proteins to bind to lipids can be exploited in the food industry to maintain food flavor and increase their nutritional value (Kinsella, 1979).The results of the water absorption capacity showed that they were significantly ( p < 0.05) lower compared with oil absorption capacity.This can be explained by the high presence of hydrophobic amino acids compared with polar amino acids in soybean proteins.
TGX 1835, MAK SOY 3N, and MAK SOY 4N exhibited significant (p < 0.05) water holding capacities compared with the other varieties.
This can be attributed to their high amount in polar amino acids in these samples compared with other varieties.Water holding capacity informs on the degree of hydration of proteins and depends on the nature of the amino acids present.These results are in agreement with the findings of Sylvia et al. (2023) who obtained water holding capacities varying between 15% and 30%.However, their oil holding capacity was significantly lower than those obtained in this study.
T A B L E 3 Oil quality parameters of soybean varieties.bulk density suggests that these flours can be used at the same level to improve the thickness of foods, which is important in the formulation of infant foods.

| Hausner ratio and porosity
The variations in Hausner ratio and porosity of the flours obtained from different soybean varieties are presented in Figure 4a,b.No significant ( p > 0.05) change in these parameters was registered among the cultivars.The Hausner ratio (Figure 4a) and porosity (Figure 4b) were ranged between 1.4 and 1.8 and 25% and 40%, respectively.
These results were in agreement with the findings of Olawoye and Gbadamosi (2017) who reported porosity varying between 26.90% and 45.53%; however, their reported Hausner ratio was significantly lower.The Hausner ratio obtained in this study was higher than 1-1.25, which characterizes flours with excellent and near free-flowing characteristics (Eltayeb et al., 2011).As far as the porosity is concerned, its high value promotes better transportation, storage, and packaging of flours obtained from these varieties (Drakos et al., 2017).

| Emulsion activity and stability
Proteins are the surface-active molecules that have that ability to form and stabilize emulsions through electrostatic repulsion on oil droplet sources (Kaushal et al., 2012).The emulsion activity and stability of different soybean flour samples are presented in Figure 5. Bernhardt, 2010).The higher interaction of proteins with other components can also explain this increase (Chinma et al., 2009).In addition, Graham and Phillips (1979) reported that emulsion stability can increase due to the formation of highly cohesive fields by the absorption of rigid globular proteins that resist to mechanical deformations.
Generally, the emulsion activity and stability was ranged between 2% and 30%, which was significantly lower than 44.37% (emulsion capacity of raw soybean) reported by Sakare et al. (2020).

| Titratable acidity and pH
The titratable acidity and pH of soybean flour solutions are exhibited in Figure 6a PUNGUNG were more acidic.It has been reported that food with higher acidity can be preserved for a longer period because their acidity inhibits the growth of microorganism and delay enzymatic reactions (Pinheiro et al., 2022).From this, we can suspect that the flours It is important to note that the flour from all these soybean varieties presented higher protein solubilities at pH 12.The increase in solubility in basic medium can be explained by structural and conformational changes due to the opening of polar amino acids by denaturation or interaction as reported by Weiss et al. (2011).This can also be explained by a change in native structures which could increase amino and carboxyl groups (Womeni et al., 2012).
Phenolic compounds are natural antioxidants found in most plants where they are used for defense.They have been demonstrated to have good antioxidant properties which make them beneficial for human studies.The total phenolic contents of the soybean varieties tested are presented in Figure1.TGX 1835, MAK SOY 4N, and SOUNG PUNGUNG 2400 presented significantly ( p < 0.05) higher total phenolic contents compared with the other varieties.The genotypic difference between these varieties can explain the variations observed.Similar results were reported byYusnawan (2018) with different soybean cultivars.However, the total phenolic content obtained in their study (2.30-2.82mg GAE/g) was significantly lower compared with the values obtained in this study.The difference in extraction methods, quantification technique, and the varieties can explain the differences observed.
± 4.72 ab 0.41 ± 0.01 b Note: Data are presented as mean ± SD (n = 3).Values within the same column with different superscript letters (a-c) are significantly ( p < 0.05) different.3.5.2 | Loose and packed bulk densitiesThe loose and packed bulk densities of soybean flour samples are shown in Figure3.No significant (p > 0.05) difference was observed in the loose and packed bulk densities of different soybean flours.However, these values were ranged between 0.4 and 0.7, which are in line with the findings ofSylvia et al. (2023),Mohajan et al. (2018), andUkwuru (2003), obtained with soybean flour samples.Bulk density is important for dietary bulk requirements and packaging of food in the industry.Loose bulk density improves food digestibility and nutrient and energy density which are an added value in food formulation(Oppong et al., 2015).The nonsignificant difference in packedF I G U R E1 Total phenolic content of the six different soybean varieties.Data are presented as mean ± SD (n = 3).Values with different superscript letters (a-c) are significantly (p < 0.05) different.F I G U R E 2 Water and oil holding capacities of six soybean varieties.Data are presented as mean ± SD (n = 2).Values with the same superscript letters (a-b and A-A) are not significantly (p > 0.05) different.
Results of emulsion activity and stability revealed significantly ( p < 0.05) higher values in TGX 1835, TGX 2001-8DM, and MAK SOY 3N compared with other varieties.The emulsion activity and stability are generally linked to the amount of oil emulsified and stabilized by the protein present in the flour(Shad et al., 2013).The difference between them is related to the nature of the proteins present, starch, and lipid composition.From the results, the flour from TGX 1835, TGX 2001-8DM, and MAK SOY 3N are more suitable to be used in food formulation.This is because their proteins were capable of increasing the emulsion formation and stability compared with those of the other varieties.The nature of the amino acids making these proteins can also explain the results obtained(Elkhalifa & ,b. Results showed no significant (p > 0.05) difference in titratable acidity (Figure 6b) of soybean flour varieties, while for the pH, TGX 1835, TGX 2001-8DM, and MAK SOY 3N presented the highest ( p < 0.05) values.From the pH value (Figure 6a), it is clear that the flours of MAK SOY 1N, MAK SOY 4N, and SOUNG

F
I G U R E 3 Loose and packed bulk densities of six different soybean varieties.Data are presented as mean ± SD (n = 2).Values with the same superscript letters (A-A and a-a) are not significantly (p > 0.05) different.F I G U R E 5 Emulsion activity and stability of six different soybean varieties.Data are presented as mean ± SD (n = 2).Values with different superscript letters (a-c) are significantly (p < 0.05) different.F I G U R E 4 (a) Hausner ratio and (b) porosity of six soybean varieties.Data are presented as mean ± SD (n = 2).Values with the same superscript letters (a-a) are not significantly (p < 0.05) different.from MAK SOY 1N, MAK SOY 4N, and SOUNG PUNGUNG have a better stability compared with the other flour due to their low pH.The pH values obtained with these flours (5.5-6.5) are in agreement with the findings of Sylvia et al. (2023) who obtained values varying between 5.5 and 7. 3.5.6| Protein solubility The protein solubility of soybean flour samples at pH 2, 4, 6, 8, 10, and 12 is presented in Figure 7. Results reported that soybean varieties TGX 2001-8DM, MAK SOY 3N, and TGX 1835 presented good protein solubilities at at-least three different pH while MAK SOY 1N, MAK SOY 4N, and SOUNG PUNGUNG were solely soluble at pH 12.
The fact that TGX 2001-8DM, MAK SOY 3N, and TGX 1835 saw their protein F I G U R E 6 (a) pH and (b) titratable acidity of flours from six different soybean varieties.Data are presented as mean ± SD (n = 2).Values with the same superscript letters (a-a) are not significantly (p < 0.05) different.soluble at least at three different pH is an advantage as their flours can have more application in food formulation compared with those from the other varieties.These results are in agreement with the findings of Dobhal and Raghuvanshi (2018) on black soybean flour.4 | CONCLUSION Making available the seedling of these soybean varieties to Cameroonian for cultivation and consumption will be beneficial to ensure food security.MAK SOY 3N, MAK SOY 4N, and TGX 1835 are richer in proteins and lipids than TGX 2001-8DM, MAK SOY 1N, and SOUNG PUNGUNG 2400.MAK SOY 4N has the highest calcium and potassium contents, while MAK SOY 3N has the highest magnesium, zinc, and iron contents.The oils from all six soybean varieties exhibited are suitable for consumption.TGX 1835, MAK SOY 4N, and SOUNG PUNGUNG 2400 are rich in phenolic compounds.Functional properties presented by all six soybean varieties are similar and in essence good, making them good ingredients for food formulation.This new varieties can be consumed by the population for nutritional purpose at the same level with the local variety TGX 1835 that has been used for years.Further research should be done on other aspects such as their antinutritional content and the fatty acid composition of their oils.
Eshun (2012)cant ( p > 0.05) difference was recorded in the fiber content of the different soybean varieties tested.The fiber content obtained was in alignment with 2.97-3.01%reportedbyEshun(2012).The presence of fibers in food facilitates digestion, prevents constipation, and helps in the regulation of the blood sugar and lipids.Proximate composition.
(Hou et al., 2009)l., 2021)1N, and SOUNG PUNGUNG 2400 presented significantly (p < 0.05) higher values compared with other varieties.As previously mentioned, the cultivar might be responsible for the variations observed.It is important to know that sugars in soybean influence the quality, digestibility, and nutritional value of soy derivatives.Glucose, fructose, raffinose, and stachyose are the main sugars found in soybean.Among them, glucose, fructose, and sucrose contribute to the sweet taste and are digestible(Mungunkhuyag et al., 2021).Raffinose and stachyose are not digested and generally cause flatulence and diarrhea(Hou et al., 2009).Note: Data are presented as mean ± SD (n = 2).Values within the same column with different superscript letters (a-d) are significantly ( p < 0.05) different.