Skip to main content
NCBI home page
Springer logoLink to Springer
. 2026 Apr 10;204(7):5094–5108. doi: 10.1007/s12011-026-05018-4

Physicochemical evaluation, Nutritional Profiles, and Fatty Acid Composition in Groundnut (Arachis hypogaea L.) and Linseed (Linum Usitatissimum) in Kamba District, Ethiopia

Mulatu Getachew Teshome 1, Dessie Ezez 1,✉, Mamo Dikamu 1, Tolera Seda Badessa 1
PMCID: PMC13320100  PMID: 41961432

Abstract

Groundnut and linseeds are the major oilseed crops of the world and are an important source of nutrients. This study aimed to evaluate the physicochemical properties, level of essential metals, and fatty acid profiles of groundnut and linseed in Kamba district, Gamo zone, Ethiopia. The results revealed that the highest saponification value (188.4, 191.67) mgKOH/g, acid value (0.99, 1.03) mgKOH/g, specific gravity (0.92, 0.94) Inline graphic, peroxide value (1.27, 1.73) meq/kg, iodine value (98.56, 176.9) gI2/100 g, carbohydrate (21.46, 21.86) %, moisture (5.03, 9.01) %, ash (3.8, 4.74) %, fibre (10.77, 14.34) %, fat (50.22, 39.94) % and protein (19.19, 21.52) % were examined for groundnut and linseed, respectively. The outcomes indicated that most of physicochemical quality parameters were in acceptable range. The levels of minerals (mg/100 g) for sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), and zinc (Zn) were ranged from 25.77 – 32.3, 32.28–40.6, 74.91–80.56, 24.62–27.57, 3.2–4.49, 5.5–5.94 for groundnut, 21.15–30.5, 26.38–38.13, 84.59–86.48, 40.48–56.48, 3.16–3.48, 4.11–4.35 for linseed samples, respectively. The current analysis of essential minerals in groundnut and linseed revealed that Mg exhibited the highest level while Fe showed the lowest. The major fatty acids found in groundnut and linseed oils were oleic acid (C18:1, 59.4%) followed by linoleic acid (C18:2, 29.03%), and palmitic acid (C16:0, 8.95%) for groundnut and linolenic acid (C18:3, 65.1%), oleic acid (C18:1, 15.59%), linoleic acid (C18:2, 12.38%), and palmitic acid (C16:0, 4.57%) for linseed samples. Oleic acid is dominant in groundnut oils whereas linolenic acid is the prominent fatty acid in linseed oil. The principal component analysis (PCA) was applied to identify the significant variables that elucidate the relationship between particular quality characteristics to categorize any group patterns. The results showed that PC1 and PC2 explained 59.60% and 40.40% for groundnut, 52.97% and 47.03% variations for linseed samples, respectively. This study confirmed that the groundnut and linseed samples cultivated in the studied areas contain high oil content with good quality for consumption.

Keywords: Physicochemical property; Nutritional profile, GC-MS; Fatty acid composition; Principal component analysis

Introduction

Oilseed crops are chief sources of lipids for human nutrition as well as for numerous industrial purposes. They are defined as those seeds that contain considerably large amounts of oil. Among various economic plants, linseed and groundnuts are well-known oil-bearing seeds in Ethiopia (Aremu et al. 2015; Getachew et al. 2023). Groundnut (Arachis hypogaea L.) belongs to the Leguminosae family and widely consumed throughout the world (Raigar et al. 2017). It is an annual crop grown mainly in the central region of Ethiopia. Groundnut is a leguminous crop rich in protein (22–30%) and fat (44–56%) and may be consumed in various forms. Groundnuts are considered as significant source of oil, folate, antioxidants, protein, and essential fatty acids (linoleic) (Oyeyinka et al. 2024; Zahran and Tawfeuk 2019). In Ethiopia, groundnuts are predominantly cultivated in sandy and poor fertile soil. Its oils have high health benefits such as maintaining cholesterol and sugar levels, enhancing memory power, retaining clear skin, and anti-aging properties (Abebe et al. 2023; Micha et al. 2023).

Linseed (Linum Usitatissimum) belongs to the Linum genus and Linaceae family, which is cultivated in high elevation areas (Beema et al. 2023). Linseed has been a traditional crop in Ethiopia and it is the second most important oil crop in production after niger (Guizotia abyssinica) in the higher altitudes (Mekebo and Chandravanshi 2014). The optimal temperature for growing and producing high yields of linseed is 10–30 °C (Jones et al. 2021). In many countries, linseed was refined for oil purposes with rich sources of omega-3 fatty acids, especially α-linolenic acid (Huang et al. 2022; Kris-Etherton et al. 2021).

The nutritional value of these oils, associated with their fatty acid, has several benefits, including lubricant, emollient, and anti-inflammatory properties (Smith et al. 2023; Zhang et al. 2023, 2024). The relationship between nutrition and health outcomes has become more prominent for consumers throughout the century (Çiftçi and Suna 2022). The storage and nutritional quality (flavour) of groundnuts and linseeds can be affected by the fatty acid composition of its oil. The oleic to linoleic acid ratio is considered to be an indicator of oil stability, and it is a shelf-life index for industrial applications (Mora-Escobedo et al. 2015; Musa 2017; Zahran and Tawfeuk 2019).

The physicochemical properties of groundnut and linseed oil is vital to inspire cultivation and consumption amongst urban dwellers (Oyeyinka et al. 2024). Food contamination by metals has become a public health concern and there is lack of knowledge about this issue in many developing nations, including Ethiopia (Ezez and Belew 2023). Minerals are involved in a wide variety of metabolic and physiologic processes in human organism whose proper functioning requires the supply of well-known quantities of necessary minerals (Ibourki et al. 2022; Karahan 2022).

Metals including sodium, potassium, calcium, magnesium, iron, and zinc are considered essential elements or mineral nutrients for the plants because of having functions in various biochemical pathways (Ozyigit et al. 2022). On the other hand, excess of some elements can have a deleterious effect on the availability of other elements leading to a negative effect on human health. Several underdeveloped countries still suffer from mineral deficiencies (Ibourki et al. 2022; Jalil et al. 2022; Ozyigit et al. 2022). The rapid trend of communities’ growth in recent decades has highlighted the need for food safety resulting in a more use of farmlands and thus rising contamination by metals in the agricultural soils owing to the extensive use of fertilizers, livestock manure and pesticides (Peirovi-Minaee et al. 2024; Taghavi et al. 2023). The study in Ethiopia showed that groundnut and linseed have recently gained popularity as a healthy food product. The physicochemical parameters and levels of metals including Na, K, Mg, Ca, Fe and Zn were evaluated and displayed significant variability between lines (Mekebo and Chandravanshi 2014). Due to the plentiful benefits of groundnut and linseed, it is therefore very imperative to examine the chemical composition and quality of these crops. From the information accessible so far, no comprehensive findings have been carried out on the chemical quality and chemical composition of these oil crops in Gamo Zone, Kamba woreda. Therefore, the objectives of this study were to (1) evaluate the physicochemical parameters (2) determine the level of essential metals (Na, K, Ca, Mg, Fe, and Zn) and (3) examine the fatty acid profile of groundnut and linseed. This study addresses the gaps by providing a detailed analysis of oils from these seeds cultivated in the studied areas.

Materials and Methods

Study Area Description

The seeds of the groundnuts and linseed for this study were collected from Kamba district, Gamo zone, Ethiopia. It was bordered on the southwest by Gardamartha, west by Ubadebretsahay, northwest by Zala, northeast by Darmalo, and east by Bonke. Many crops are grown in Kamba woreda such as groundnut, linseed, wheat, pea, and bean. Kamba is located northwest of Arba Minch town, 635 km from Addis Ababa and 105 km from Arba Minch with longitudes of 370 4’ 32” E to 37017’51"E and latitudes of 550 6’ 34” N to 60 17’ 29” N. The average temperature and rainfall of this area is 10.1 to 27.5 °C and 801 to 1600 mm/annum, respectively (Meta 2018).

Chemicals and Reagents

For this study, analytical grade chemicals were used. Hexane (Sisco Research laboratory, Pvt. Ltd. Mumbai, India) for extraction, Potassium hydroxide (Mumbai, India), Sodium thiosulphate (Loba Chemie Pvt. Ltd., India), Chloroform (Sisco research laboratories Pvt. Ltd., Mumbai India), Potassium iodide (Abron Chemicals), hydrochloric acid (Blulux Laboratories (P) Ltd.), and Sodium hydroxide (Loba Chemie Pvt. Ltd., India), nitric acid (HNO3 69–72%, Loba Chemie PVT LTD, India) and perchloric acid (70%, Sisco research laboratories PVT LTD, India) were used. Instruments used for the analysis were flame atomic absorption spectrometer (Buck scientific model, 210 VGP, USA) for metal determination and Muffle furnace (FUSEF1AH, R000047 UK) was used for ashing purpose.

Sample Collection and Preparation

The groundnut and linseed seeds were purchased during the same harvesting season from local farmers in Otolo, Maze and Hanika Sobo. The samples were transported to the Arba Minch University Chemistry Research Laboratory for the analysis. The seeds and pod shells were separated manually. All samples were carefully washed with deionized water and oven dried at 105 °C in the laboratory. The mature and healthy seeds were grounded using grinding mill and stored at 4 o C in cool and dry place in glass containers.

Extraction of Oil from Groundnut and Linseed

Extractions of oils for groundnut and linseed were conducted by Soxhlet extraction methods with slight modifications (AOAC) described elsewhere (Bayisa and Bullo 2021). The grinded samples were placed in a thimble and loaded into the Soxhlet extraction unit and the extraction flasks were filled with 200 mL of hexane. A solid-to-solvent ratio of 1:10, extraction time 4 to 6 h, temperature 55 to 70 °C, and particle size of 0.5 to 1.5 mm was employed. After the complete extraction, the samples were concentrated using rotary vapour with specific boiling point of the solvent using 200 mL bar pressure and 50 rpm of the flux until complete removal of the solvent. The final oil from each extract was allowed to cool separately.

Physicochemical Analysis of Groundnut and Linseed

Analysis of Moisture Content

The moisture content of groundnut and linseeds were measured by following the methods described by (Raigar et al. 2017). 5 g of each of the samples were placed in the oven at 105 Inline graphic until the constant weight was obtained. The moisture contents were determined in terms of the percentage of the original weight of the sample.

graphic file with name d33e333.gif 1

 

where w1 is the weight of the dish and undried sample, w2 = weight of dish and dried sample, and W3 = weight of initial sample.

Determination of Ash Content

3 g of groundnut and linseed samples were ashed in the furnace at a temperature of 550 ℃ for 4 h. The residues were allowed to cool at room temperature and then weighed (Ezez and Belew 2023). The ash content of samples was calculated using the following formula.

graphic file with name d33e353.gif 2

Fibre Content Analysis

The fibre content of groundnut and linseed samples were evaluated using the procedure described by (Ezez and Belew 2023). 3 g of samples mixed with 1.25% H2SO4 in 200 mL beaker and the mixture was heated for 30 min. The residue was washed with boiled water and mixed with 200 mL of 1.5% NaOH followed by heating and filtration. The residue was ashed in a muffle furnace at 550 ℃ for 2 h. The fibre content was determined using the Equion 3.

graphic file with name d33e371.gif 3

 

where W1= weight of sample before burning W2= weight of sample after burning W3 = weight of the original sample.

Determination of Crude Protein

For this study, 0.5 g of samples were digested using Kjeldahl apparatus. A catalyst mixture of 1.0 g of K2SO4 and anhydrous CuSO4 were added to the flask. Afterwards, 12.5 mL of 98% H2SO4 was added to the mixture. The digested solutions were diluted in 200 mL volumetric flask. 50 mL of digested solutions were transferred into a distillation flask and 50 mL of 40% NaOH was added to the solution. The liberated ammonia was trapped in 50 mL of 4% boric acid solution to which two drops of mixed indicator (bromocresol green and methyl red). The borate anion proportional to the amount of nitrogen was titrated with 0.1 mol/L H2SO4 until light pink colour.

was observed (Kassaw et al. 2023). The level of crude protein was determined using the following equation.

graphic file with name d33e408.gif 4

 

Where A and B are titre volume in litter of sulphuric acid required for the experiment and blank titrations, respectively, N- normality of standard sulphuric acid used; and w is weight (g) of sample, 14 is atomic mass of nitrogen.

graphic file with name d33e415.gif 5
graphic file with name d33e421.gif 6

where 5.46 and 6.25 are conversion factors of protein in groundnut and linseed, respectively (Puwastien et al. 2011).

Determination of Fat Content

The fat content of groundnut and linseeds were determined by taking 20 g of each samples using soxhlet extraction apparatus. The Soxhlet apparatus was then assembled and the sample solution was allowed to reflux for 6 h using 200 mL of hexane following the procedure modified by (AOAC, 2000) (Kassaw et al. 2023). The mixtures were boiled at 70 Inline graphic until removal of solvents and cooled in the desiccator. The weight of samples was weighed and the contents of fat were calculated using Eq. 7.

graphic file with name d33e445.gif 7

 

Determination of Carbohydrate Content

Total carbohydrate content was determined by adding the total values of crude protein, crude fat, crude fibre, moisture and ash constituents of the sample and subtracting it from 100 (Kassaw et al. 2023).

graphic file with name d33e457.gif 8

Determinations of Acid Value

The acid values of the oil were examined by the methods (Azuokwu et al. 2024; Olaoye et al. 2021) with slight modification. Briefly, 25 mL of diethyl ether and 25 mL of ethanol were mixed and warmed on a hot plate for 3 min to remove the dissolved gases in the mixture. 1 g of oil was dissolved and warmed on a hot plate for 30 min. Two drops of 1% of phenolphthalein were added to the solution and titrated against 0.1 M KOH. The acid value was calculated using Eq. 9 (Zeleke Tilinti et al. 2023).

graphic file with name d33e477.gif 9

where M-Concentration of KOH, V- titre values (mL), 56.1- molecular weight of KOH (g/mol), and W- Weight of oil sample (g).

Determinations of Saponification Value

One gram of crude oil was dissolved in 25 mL of 0.5 N of alcoholic KOH, refluxed for 45 min, cooled, and 1 mL of phenolphthalein was added. The solution was titrated against 0.5 M HCl. A blank determination was also analysed similar with sample solutions.

The volume of HCl was recorded and the saponification values were calculated as Eq. 10 (Pardeshi 2019a).

graphic file with name d33e495.gif 10

where; B-Volume in mL of standard HCl consumed by blank solution, S-Volume in mL of standard HCl Consumed by Sample; N- Normality of Standard HCl; W- Wight in a gram oil taken for analysis.

Determinations of Peroxide Value

For this study, 30 mL of acetic acid–chloroform solution (3:1), 2 g of the extracted oil, and 0.5 mL of potassium iodide were added to Erlenmeyer flask and shaken continuously. 0.1 M sodium thiosulphate (Na2S2O3) solution was used to titrate against 30 mL of water (30 mL) until the original yellow color vanished and a light blue tint appeared. 0.5 mL of 1% starch was added and the mixture was titrated until the blue color disappeared (Abeer et al. 2020; Gore et al. 2023). The peroxide values were calculated by applying Eq. 11 (Wazed et al. 2023).

graphic file with name d33e524.gif 11

Where S-Sample titre Volume (mL), B- Blank titre Volume (cm3), M- Molarity of Na2S2O3.

Determinations of Iodine Value

For the current finding, 1 g of oil were dissolved in 20 mL of carbon tetrachloride and 250 mL of glacial acetic acid. The mixture was allowed to stand in the dark for 1 h with occasional shaking. Then, 20 mL of 15% KI was added (Shiferaw et al. 2019). After incubation,100 mL of distilled water was added and titrated against 0.1 M Na2S2O3 until yellow solution turned its colour. Then a few drops of 1% starch indicator was added and titration was continued until the blue colour disappeared. The iodine value was calculated using Eq. 12 (Idrissi et al. 2024).

graphic file with name d33e558.gif 12

where C- Concentrations of Na2S2O3, V1- Volume of Na2S2O3 consumed by blank, V2- Volume of N2S2O3 Consumed by the sample. W- Weight of oil, 12.69- Conversion Factor.

Determinations of Specific Gravity

Specific gravity was determined with a slight modification of the AOAC procedure described by (Lumpur 2019). Weighed specific gravity bottle of 50 cm 2 capacity was filled with distilled water of 35 Inline graphic to over flow and inserted the stopper. After the 30 min the bottle was removed from the water bath and wiped dry. The weight of the bottle and the content was taken and cooled to 35 Inline graphic and filled to dried specific gravity bottle.

The specific gravity was assessed using the following formula (Olaoye et al. 2021; Shawhatsu 2022).

graphic file with name d33e612.gif 13

where W0 = weight for bottle in grams, W2 = weight of bottle + water in grams.

W3 = weight of bottle + oil sample in gram.

Analysis of Metals in Groundnut and Linseed

To prepare a clear and colourless solution suitable for the analysis of metal levels in groundnut and linseed samples, wet digestion procedure was confirmed. Briefly, 1 g of each seed samples were digested with a mixture of 10 mL of 70% HNO3 and 3 mL of 60% HClO4 at 200 ℃ for 1:20 h for groundnut and 6 mL of 70% HNO3 and 5 mL of 60% HClO4 at 180 ℃ for 1:35 h for linseed samples until clear and colourless solutions were obtained (Audu Chomo et al., 2023). The digested solutions were allowed to cool for 3 h at room temperature. The solution was filtered using Whatman filter paper (No 41), then diluted with distilled water in 50 mL volumetric flask. Digestion was made in triplicates for each bulk sample. Digestion of blank was achieved in parallel by keeping all digestion procedures the same as samples (Kassaw et al. 2023). For quantitative determination, the blank, working standards and samples were run in triplicates for each analytical development. The systematic procedure for metal evaluation, calibration curves were prepared using different working standard solutions. To achieve its superior sensitivity, the working standards were pronounced one after the other in to the flame atomic absorption spectrometer and its absorbance was recorded (Tefera et al. 2025).

GC-MS Analysis of Fatty Acid

The fatty acid profiles in groundnut and linseed samples were identified using GC-MS after the esterification of fatty acids into methyl ester (Yuenyong et al. 2021). 0.6 g of groundnut and linseed oils were added separately to the flask containing 6 mL of 2 N KOH in methanol solution. The mixture was heated in a water bath at 80 °C for 1 h and allowed to cool. Briefly, 10 mL of 5% HCl in methanol solution was boiled in water bath at 80 o C for 1 h. After cooling, 3 mL of hexane and 3 mL of H2O were added and centrifuged. Finally, the aqueous layer from hexane was separated and hexane layer was taken into a vial. The Agilent Technology (GC-8890 A system equipped with 5977B inert mass selective detector, 7693 A autosampler injector (10 µL in size) with an HP-5MS fused silica capillary column (30 m × 0.25 mm ID × 0.25 µL) continued with (70 eV) for GC operations. Helium gas (99.995%) was used as the carrier gas with the flow rate of 1.5 mL/min and 1µL of the sample. The solvent delay of 3 min and a split ratio of 10:1 was injected into the GC column. The oven temperature was adjusted at 90 °C and held for 2 min then ramped at 4 0 C/min to 152 o C for 1 min at the rate of 2 °C/min to 218 o C. Finally ramped to 260 °C at a rate of 20 °C/min. The mass spectrum was developed in the scan mode and the analysis of main fatty acid was interpreted using NIST library (Hagos et al. 2023; Olajuyigbe et al. 2019; Yuenyong et al. 2021).

Data Analysis

Experimental values were expressed as mean ± SD for triplicate measurements. All determined data were statistically analysed by using the SPSS version 26 software. To check the statistical differences between the parameters, Tukey’s post hoc multiple compressions analysis with P < 0.05 probability levels were employed. Principal Component Analysis (PCA) was applied to reduce the dimensionality of complex datasets while preserving the most important information.

Results and Discussion

Physicochemical Characterization of Groundnut and Linseed

Moisture Content Analysis

The moisture content is a key component of oil stability and rancidity (Ashong et al. 2024). The result of the proximate composition for the studied seeds illustrated in Table 1. The average moisture contents of groundnut and linseed in different areas were ranged from 4.35% to 5.03% and 6.54–9.01% with the highest value recorded in Maze (5.03 and 9.01%) whereas the lowest values recorded in Otolo (4.35%) and Hanika Sobo (6.54%) samples, respectively. The outcomes of the studied samples were in agreement with the results ranged from 3.35 to 5% reported in India (Jain et al. 2023), 4.37% (Parameshwari and Nazni 2015) for linseed, in Egypt (4.27–4.85%) (Zahran and Tawfeuk 2019), in Ethiopia (4.51–5.41%) (Belete and Bayissa 2020), India (1.13–6.93%) (Raigar et al. 2017), but lower than in India (1.14–2.16) % (Pardeshi 2019b) for groundnut. For this study, the moisture contents were lower than the standards (7–11%) described by (AOAC, 1990) (Audu Chomo et al., 2023). Low moisture content can result in low rate of oil rancidity with long life span of the sample. Therefore, there is less activities of microorganisms subsequently increasing the shelf life of the seeds.

Table 1.

Physicochemical quality parameters in groundnut and linseed samples.

Sample Location Nutritional values of oil crops (mean ± SD, n = 3)
SV
(mg KOH/g)		 AV
(mgKOH/g)		 SG at 25 0 C PV
(meq/kg)		 IV
(g I2/100 g)		 CHO (%)
Groundnut Otolo 177.65± 0.8a, d 0.65± 0.16a, d 0.92±0.6a, d 0.93±0.20a, d 88.41±0.94a, d 21.46±0.87a, d
Maze 186.06± 1.62b, e 0.84± 0.28 b, e 0.88±0.8b, e 1.17±0.20b, e 86.71±0.66a, 18.61±0.42b, e
Hanika 188.40± 0.81c, f 0.99± 0.14 c, f 0.89±1.04a, e 1.27 ±0.21c, f 98.56±0.28b, f 17.97±0.66b, e
Linseed Otolo 191.67±1.62a, g 0.75± 0.32a, g 0.92± 0.62a, f 1.5±0.15a, d 173.85±0.4a, g 14.86±0.51a, f
Maze 186.06±1.62b, h 0.93± 0.43b, h 0.94± 0.8b, e 1.3±0.15b, g 176.9±0.1a, h 14.43±0.20a, f
Hanika 183.72±1.4c, i 1.03± 0.16c, i 0.92± 0.69b, g 1.73±0.15c, h 175.54±0.9a, i 21.86±0.82b, d
Moisture (%) Ash (%) Fibre (%) Fat (%) Protein (%)
Groundnut Otolo 4.35±0.16a, d 3.80±0.48a, d 7.17±0.39a, d 47.30±0.22a, d 15.92±0.92a, d
Maze 5.03±0.11b, e 3.80±0.07a, d 4.32±0.63b, e 50.22±0.57b, e 18.03±0.87b, e
Hanika 4.77±0.17a, d 3.52±0.20a, d 10.77±0.38c, f 43.79±0.84c, f 19.19±0.61c, f
Linseed Otolo 7.56±0.18a, f 4.17±0.23a, e 11.94±0.67a, g 39.94±0.49a, g 21.52±0.35a, g
Maze 9.01±0.06b, g 4.74±0.12a, e 14.34±0.05b, h 37.42±0.26b, h 20.07±0.27b, h
Hanika 6.54±0.80c, h 4.77±0.27a, e 10.57±0.37c, i 36.58±0.40b, h 19.34±0.09b, h
Open in a new tab

Analysis of Ash Contents

The ash contents outlined in the study locations were in the following descending order: Hanika Sobo (4.77%) Inline graphicMaze (4.74%) > Otolo (4.17%) for linseed and Otolo (3.80%) = Maze (3.80%) > Hanika Sobo (3.52) for groundnut Table 1. The Hanika Sobo sample contained the highest ash content (4.77%) while Otolo sample showed the lowest ash value (4.17%) for linseed as well as the highest ash content was observed in Otolo and Maze (3.80%) for groundnut sample. The ash contents were in agreement with the (AOAC, 1990) standards of 2–5% provided (Audu Chomo et al., 2023). Therefore, the studied oil crops revealed significant amount of ash, which is an important source of minerals. The result of this study was in accordance with the findings conducted in Nigeria (3.05%) (Audu Chomo et al., 2023) for oil seeds, but lower values were examined in China (0.95–1.78%) reported by (Fan et al. 2024).

Analysis of Fibre Contents

The average fibre contents investigated in different areas were Otolo (7.17%), Maze (4.32%), and Hanika Sobo (10.77%) for groundnut and Hanika Sobo (10.57%), Maze (14.34%), and Otolo (11.94%) for linseed samples. The highest content of fibre was found in Hanika Sobo (10.77%) for groundnut and in Maze (14.34%) for linseed samples. In previous reports equivalent amount of fibre contents were noted in Ethiopia (7.63–10.27%) for Lepidium sativum seeds (Feleke et al. 2023), but lower values were conducted in Ethiopia (2.31–2.80%) (Belete and Bayissa 2020) and India (2.24–3.18%) (Pardeshi 2019b) for groundnut. However, greater value of fibre contents were recorded in China in the range (86.04–96.02%) (Fan et al. 2024).

Fat Content

The low-level consumption of fat has a negative effect on cognitive development and the immune functions of the children, and sufficient fat intake is worthy for mental development and the immune system (Jahan et al. 2021). The distribution pattern of oil contents was ranged from 43.79 to 50.22% for groundnut and 36.58–39.94% for linseed samples. Investigation of groundnut and linseed seed samples showed that the highest oil contents in groundnut and linseed were found in Maze (50.22%) and Otolo (39.94%) while the lowest values were explored from Hanika Sob (43.79% and 36.58%), respectively. Most of the results were equivalent with the results from all study presented in Table 1. The finding of current study were in a good agreement with the results (39.1%) reported by (Kumar et al. 2013), (37.61– 41.71%) (Belete and Bayissa 2020), (50.45–52.12%) (Zahran and Tawfeuk 2019), but greater than the results (23.33–29.41%) (Khadra et al. 2022) for groundnut and (23–29.18%) (Jain et al. 2023) for linseed.

Protein Content

Proteins are building blocks of human body needed for growth, development, and body repair cells (Nagrale et al. 2018). According to this study, the protein contents were recorded as 15.92%, 18.03%, 19.19% for groundnut and 21.52%, 20.07%, and 19.34% for linseed in Otolo, Maze and Hanika Sobo samples, respectively Table 1. The protein contents were almost similar to the values (16.38–18.14 g/100 g) obtained by (Jain et al. 2023) for linseed, (24.9–26%) (Kumar et al. 2013), (25.07–28.2%) (Zahran and Tawfeuk 2019), but greater than the range of values (0.77–1.07%) performed by (Khadra et al. 2022) and lower than the finding (42.3–45.4%) (Belete and Bayissa 2020) for groundnut.

Carbohydrate Content

Carbohydrates are the principal energy sources for the human body. Carbohydrates not only represent the most accessible source of energy for our body, but also play an important role in many physiological processes (Kassaw et al. 2023). The recommended dietary allowance of carbohydrate is (46–56) g per day. The tolerable upper intake is 25% of the energy intake (Nagrale et al. 2018). The carbohydrate values in groundnut and linseed samples were found in the range 17.97–21.46% and 14.43–21.86%, respectively Table 1. The highest value of carbohydrate was found in Otolo (21.46%) and Hanika Sobo (21.86%) followed by Maze (18.61%) and Otolo (14.86%) while the lowest value was examined in Hanika Sobo (17.97%) and in Maze (14.43%) for groundnut and linseed, respectively. The value of carbohydrates in the present finding were comparable with the results ranged from 17.61 to 22.37% of previous study reported by (Zahran and Tawfeuk 2019), 25.3–26% (Kumar et al. 2013), but lower than the values (34.41–37.76%) (Pardeshi 2019b) for groundnut and 29.62–35.64% (Jain et al. 2023) for linseed.

Saponification Value

The molecular weight of acids in the oil was directly related to the saponification value of the oil (Mengistie et al. 2018). For the present investigation, saponification values were ranged from 177.65 to 186.06 mg KOH/g for groundnut and 183.72–191.67 mg KOH/g for linseed. According to the finding Table 1, the Hinka Sobo sample depicted higher saponification value for groundnut (188.4 mg KOH/g) followed by Maze sample 186.06 mg KOH/g while the lowest value was recorded in Otolo sample (177.65 mg KOH/g). However, the linseed samples were found in the following descending order Otolo (191.67 mg KOH/g) > Maze (186.06 mg KOH/g) > Hanika Sobo (183.72 mg KOH/g). The saponification values in groundnut obtained in this study were slightly lower than the FAO/WHO standard of edible oils except Hanika Sobo samples. This study agreed with the literature values of soybean (187.1 mg/g), palm (202.39 mg/g), mustard (191.38 mg/g), and bran oil (81.6 mg/g) reported by (Wazed et al. 2023). The saponification values of linseed oil greater than groundnut oils which indicated that linseed oil contains many fatty acids of low molecular weight (Beema et al. 2023; Olaoye et al. 2021; Wazed et al. 2023).

Acid Value

The acid value is a decent indicator of the degradation of oil caused by hydrolysis or enzymes (Mengistie et al. 2018). The higher the free fatty acid level which corresponds to the hydrolysis of triglycerides and hence a decreased oil quality (Ishag et al. 2019). The acid values of oils calculated in groundnut were 0.65 mg KOH/g, 0.84 mg KOH/g and 0.99 mg KOH/g as well as the values in linseed samples were 0.75 mg KOH/g, 0.93 mg KOH/g and 1.03 mg KOH/g for Otolo, Maze and Hanika Sobo samples respectively Table 1. According to the present discovery, the acid values were slightly higher compared to FAO/WHO (1999) specification (≤ 0.6 mg KOH/g of oil (Babandi et al. 2017). The higher acid values are indicative of free fatty acids present in the groundnut and linseed oil, which may be as a result of exposure to atmospheric oxygen or probably due to the method used for the extraction and the moisture contents (Babandi et al. 2017). The levels of free fatty acid rise with increasing acid values which reduces oil quality (Beema et al. 2023).

Peroxide Value (PV)

Peroxide value (PV) measures the rancidity during the storage and stability of oils. Lower PV indicates reduced levels of oxidative rancidity of the oil and suggests the strong presence or high levels of antioxidants. A rancid taste often becomes noticeable when the PV exceeds 20 meq/kg (Mengistie et al. 2018). The estimated peroxide value of oils extracted in groundnut were 0.93 meq/kg, 1.17 meq/kg, and 1.27 meq/kg as well as in linseed were 1.5 meq/kg, 1.3 meq/kg and 1.73 meq/kg for Otolo, Maze and Hanika Sobo samples, respectively Table 1. These results were lower than the previous reports (2.18–2.67) meq/kg investigated by (Olaoye et al. 2021) for groundnut and 4.67 meq/Kg (Ishag et al. 2019) for linseed. The peroxide value of linseed oil greater than groundnut oil, i.e. high oil qualities were presented for linseed. In current study, the peroxide value of both linseed and groundnuts were found within the acceptable range (10 meq/Kg) prescribed by CODEX-STAND − 1999. Peroxide value is the degree of peroxides and hydro peroxides formed in the initial phases of lipid oxidation. When double bonds of unsaturated fatty acids present in oil are oxidized, peroxides are among the oxidation formed as unsaturated fatty acids are responsible for oxidative rancidity (Babandi et al. 2017).

Iodine Value

The iodine values of groundnut and linseed samples were ranged from (86.71–98.56) g I2/ 100 g and (173.85–176.39) g I2/100 g, respectively Table 1. The highest Iodine value was recorded in Hanika Sobo (98.56 g I2/100 g) followed by Otolo (88.41 g I2/100 g) for groundnut and in Maze (176.90 g I2/100 g) followed by Hanika Sobo (175.54 g I2/100 g) for linseed samples. Determination of iodine value revealed the occurrence of saturated and unsaturated fatty acids in the sample. The higher the iodine value, the more the unsaturation and the higher the exposure to oxidation (Idrissi et al. 2024; Olaoye et al. 2021; Suri et al. 2023; Xiao et al. 2022). This finding was lower than the results of earlier study (187.36–I2/100 g) (Oyeyinka et al. 2024). The decrease in iodine value indicates oil oxidation, possibly due to metallic ions present among other factors that enhance or promote oxidation after hydroperoxide formation (Oyeyinka et al. 2024).

where SV = saponification value, AV = acid value, PV = peroxide value, IV = iodine value, SG = specific gravity, CHO = carbohydrate content. For each sample locations, values in the same column for each sample followed by different letters (a–c) are significantly different (P < 0.05). For each oil crop sample, values in the same column for each sample followed by different letters (d–i) are significantly different (p < 0.05) by Tukey’s multiple comparison tests.

Specific Gravity

The oil-specific gravity values were distributed in descending order as follows: Otolo (0.92) > Hanika Sobo (0.89) > Maze (0.88) for groundnut and Maze (0.94) > Otolo (0.92) = Hanika Sobo (0.92) for linseed oil. The highest specific gravity was observed in Otolo (0.92) and Maze (0.94) whereas the lowest values of the specific gravity was determined in Maze (0.88), Otolo and Hanika Sobo (0.92) Table 1. The findings closely agreed with the study performed by (Oyeyinka et al.(2024). The lower specific gravity value indicates the high quality of oil (Abeer et al. 2020; Sufiyanu and Na’ala 2022). For this study, the specific gravity of groundnut and linseed oil were in the acceptable range described by (CODEX-STAND − 1999). ( (p

Concentrations of Metals in Groundnut and Linseed

Minerals like Na, K, Mg, Ca, Fe, and Zn are essential in meeting the essential nutritional needs of humans. They regulate water retention and maintenance for the activation of various metabolic processes within the body (Christian Ebere 2019; Kassaw et al. 2023). Deficiency of primary macronutrients were found to considerably affect the yield and quality of oil seed crops (Zafar et al. 2023). The levels of six essential metals such as Na, K, Mg, Ca, Fe, and Zn in groundnut and linseed from Otolo, Maze and Hanika Sobo are shown in Table 2. The average concentration of metals in the descending order were as follows: Mg > K > Na > Ca > Zn > Fe for groundnut and Mg > Ca > K > Na > Zn > Fe for linseed samples, respectively. The average level of Mg in both groundnut and linseed samples was found to be higher compared to other essential metals examined.

Table 2.

Mineral contents of groundnut and linseed samples in different study areas

Name Locations Level of metals (mean ± SD, mg/100 g, n = 3)
Sodium Potassium Magnesium Calcium Iron Zinc
Groundnut Otolo 26.21±1.52a, d 32.28±1.34a, d 75.74±0.28a, d 27.57±0.14a, d 3.72±0.51a, d 5.70±0.05a, d
Maze 25.77±0.49a, e 40.60±1.24b, e 74.91±0.41a, e 24.62±0.09b, e 4.49±0.32b, d 5.94±0.14a, e
Hanika Sobo 32.30±0.20b, f 32.87±0.07a, f 80.56±1.21b, f 26.02±0.02c, f 3.20±0.02a, d 5.50±0.11a, f
Linseed Otolo 21.15±0.43a, g 38.13±0.52a, g 86.48±0.29a, g 53.16±0.17a, g 3.16±0.04a, d 4.21±0.12a, g
Maze 23.18±0.24b, h 26.38±1.13b,a 85.02±0.43a, h 40.48±0.45b, h 3.84±0.02a, d 4.11±0.20a, h
Hanika Sobo 30.50±0.30c, f 35.93±0.49a, h 84.59±0.51a, i 56.48±0.04c, i 3.30±0.01a, d 4.35±0.01a, i
Open in a new tab

Sodium is an essential metal that regulates blood volume, blood pressure, osmotic equilibrium. The minimum physiological requirement for sodium is estimated to the range from 120 mg/day in new born to 500 mg/day over the age of 10 (Kassaw et al. 2023). The average levels of Na in the studied areas were found in decreasing order as follows: Hanika Sobo (32.3 mg/100 g) > Otolo (26.21 mg/100 g) > Maze (25.77 mg/100 g) for groundnut and Hanika Sobo (30.5 mg/100g) > Maze (23.18 mg/100 g) > Otolo (21.15 mg/100 g) for linseed samples. The highest level of Na in groundnut and linseed was found in Hanika Sobo (32.3 mg/100 g and 30.5 mg/100 g), respectively. The level of Na were lower than the values 35–56.9 mg/100 g in Nigeria reported by (Sanni et al. 2024), but in accordance with 19–48 mg/100 g (Asibuo et al. 2008) for groundnut, but comparable with 242–614 mg/kg in Ethiopia (Mekebo and Chandravanshi 2014) for linseed. The level of Na required to maintain homeostasis in adults is remarkably low (< 500 mg) compared to the mean consumption of most Americans (> 3200 mg) (Beshaw et al. 2022).

The tolerable intake of potassium was 3400 mg/day for adult males and 2600 mg/day for adult females. The recommended consumption by Americans is 2591 ± 9 mg/day (Beshaw et al. 2022; Kassaw et al. 2023). In the current investigation, the mean level of K was ranged from 32.28 to 40.60 mg/100 g for groundnut and 26.38–38.13 mg/100 g for linseed samples. The maximum amount of K was recorded in Maze (40.6 mg/100 g) followed by Otolo (38.13 mg/100 g) whereas the lowest levels were noted in Otolo (32.28 mg/100 g) followed by Maze (26.38 mg/100 g) for groundnut and linseed samples, respectively. According to the findings in Table 2, results were lower than the previous reports in Ethiopia (6494–6755 mg/kg) (Mekebo and Chandravanshi 2014) for linseed and in Ghana (1180–1610 mg/100 g) (Asibuo et al. 2008) for groundnut.

Magnesium is a mineral necessary in small quantities, to make the body function appropriately (Christian Ebere 2019). The suggested daily ingestion of Mg is 400–420 mg/day for men and 310–320 mg/day for women and the average consumption of Mg in oil crops was (412.68 mg/day) (Beshaw et al. 2022; Kassaw et al. 2023). In the current study, the levels of Mg in Otolo, Maze and Hanika Sobo were 75.74 mg/100 g, 74.91 mg/100 g, and 80.56 mg/100 g for groundnut and 86.48 mg/100 g, 85.02 mg/100 g, and 84.59 mg/100 g for linseed samples, respectively Table 2. The level of Mg in the present study was significantly higher than the literature values (1.39 − 1.42 mg/kg) conducted by (Belete and Bayissa 2020), however, significantly lower than reports 209.5–210.3 mg/kg (Kumar et al. 2013) and 2679–3118 mg/kg (Mekebo and Chandravanshi 2014), but equivalent with the literature values (Sanni et al. 2024).

Calcium plays a significant role in the health of bones as well as in regulating blood pressure. The maximum tolerable limit for Ca is 2500 mg/day for adults aging 19–50. For those 51 and older, the limit is 2000 mg/day (Beshaw et al. 2022; Kassaw et al. 2023). The levels of Ca in different areas were found in the decreasing order: Otolo (27.57 mg/100 g) > Hanika Sobo (26.02 mg/100 g) > Maze (24.62 mg/100 g) for groundnut and Hanika Sobo (56.48 mg/100 g) > Otolo (53.16 mg/100 g) > Maze (40.48 mg/100 g) for linseed Table 2. These results highlight the varying mineral profiles in these oilseed crops, which have implications for nutritional value, soil management, and agricultural practices. On average, the level of Ca in linseed sample was higher than groundnut. The results reported in this study were in agreement with the literature (540–744 mg/kg) (Mekebo and Chandravanshi 2014) for linseed, however, lower than the finding in India (Kumar et al. 2013) for groundnut.

Iron is an essential element in human body metabolism acting as a catalyst. Adequate iron is very important for decreasing the incidence of anaemia (Kassaw et al. 2023). The deficiency of iron in the blood can lead to the serious health problems (Ezez and Belew 2023). The level of Fe in Otolo, Maze, and Hanika Sobo were 3.72 mg/100 g, 4.49 mg/100 g, and 3.2 mg/100 g for groundnut and 3.16 mg/100 g, 3.84 mg/100 g, and 3.3 mg/100 g for linseed samples, respectively (Table 2). The highest concentration of Fe was determined in Maze samples in both oil crops while the lowest level was found in Hanika Sobo for groundnut and in Otolo for linseed. The level of Fe from the studied samples were below the recommended safety limits for adults (45 mg/day). According to the previous study in Ethiopia (Belete and Bayissa 2020) and Nigeria (Sanni et al. 2024), lower content of Fe was noted than this study for groundnut. However, greater Fe level was observed in Ethiopia (Mekebo and Chandravanshi 2014), but lower concentration in Nigeria (Opaluwa et al. 2012) for linseed samples.

Zinc is essential for the proper functioning of the immune system. It facilitates division and growth of cells; wound healing and carbohydrate catabolism (Ezez and Belew 2023). The level of Zn in groundnut and linseed samples were varied in the range between 5.50 and 5.94 mg/100 g and 4.11–4.35 mg/100 g, respectively Table 2. The average level of Zn was similar for the investigated oil crops. The outcome of this study revealed that equivalent amount of Zn was found examined by (Asibuo et al. 2008), but the least level of Zn was also reported (Sanni et al. 2024) for groundnut, and comparable levels was also recorded (Mekebo and Chandravanshi 2014). The limitation of this study is lack of comprehensive analysis of physicochemical and nutritional composition of groundnut and linseed in the studied areas.

For each sample locations, values in the same column for each sample followed by different letters (a–c) are significantly different (P < 0.05). For each oil crop sample, values in the same column for each sample followed by different letters (d–i) are significantly different (p < 0.05) by Tukey’s multiple comparison tests.

GC-MS Analysis of Fatty Acids

Linseed and groundnut have been known as a good source of oil with significant proportion of highly unsaturated fatty acid content (Qiu et al. 2020). Fatty acids are the main units for synthesizing certain biologically active substances (Sokoła-Wysoczańska et al. 2018). GC-MS is one of the most common tool for identifying and quantifying fatty acid profiles (Hagos et al. 2023). The GC-MS analysis of the fatty acid profiles in groundnut and linseed oil were presented in Table 3. Fatty acid profiles of the studied oil crops were confirmed using retention time, percentage area, molecular weight, and chemical formula of the fatty acids. The major fatty acids found in groundnut and linseed oils were oleic acid (C18:1, 59.4%) followed by linoleic acid (C18:2, 29.03%), and palmitic acid (C16:0, 8.95%) for groundnut Fig. 1A and linolenic acid (C18:3, 65.1%), oleic acid (C18:1, 15.59%), linoleic acid (C18:2, 12.38%), and palmitic acid (C16:0, 4.57%) for linseed samples Fig. 1B. This finding was similar with the oleic acid (C18:1, 39.71–55.89%), linoleic acid (C18: 2, 2021–35.59%), palmitic acid (C16:0, 11.91–17.16%) reported by (Musalima et al. 2019), oleic acid (C18:1, 53.18%), linoleic acid (C18: 2, 29.74%) and palmitic acid (C16:0, 12.43%) (Niamayoua et al. 2015), oleic acid (C18:1, 56.02–62.93%), linoleic acid (C18:2, 19.56–23.33%), palmitic acid (C16:0, 12.01–14.96%) (Zahran and Tawfeuk 2019) for groundnut, linolenic (C18:3, 58.8%), oleic (C18:1, 17%), linoleic (C18:2, 15.9 5), palmitic (C16:0, 4.58%) (Tanska, 2025), linolenic (C18:3, 39.91–47.61%), oleic (C18:1, 22.6– 28.26%), linoleic (C18:2, 17.8–18.1%), and palmitic (C16:0, 6.85–8.83%) (Atti et al. 2013) for linseed.

Table 3.

Fatty acids identified from groundnut and linseed oils in hexane extract of Maze samples

Oil type Compound Name Formula RT MW (g/mol) Area (%) Chemical Class
Groundnut Palmitic acid C17H34O2 32.8 270.45 8.952 long chain saturated fatty acids
Linoleic acid C19H34O2 39.87 294.47 29.03 polyunsaturated fatty acids
Oleic acid C19H36O2 40.15 296.48 59.4 monounsaturated omega-9 fatty acid
Octadecanoic acid C19H38O2 41.32 298.5 1.868 long-chain saturated fatty acids
Eicosanoic acid C21H42O2 49.57 326.55 0.730 long-chain saturated fatty acid
Linseed Palmitic acid C17H34O2 32.796 270.45 4.577 Long chain saturated fatty acids
Linolenic acid C19H32O2 40.13 292.45 65.1 polyunsaturated fatty acid
Oleic acid C19H36O2 41.308 296.48 15.59 monounsaturated omega-9 fatty acid
Linoleic acid C19H34O2 42.66 294.47 12.38 polyunsaturated fatty acids
Open in a new tab

RT = retention time (min), MW = molecular weight (g/mol)

Fig. 1.

Fig. 1

Open in a new tab

The chromatogram of fatty acid profiles in groundnut (A) and linseed (B) along with their retention time

The composition of groundnut and linseed oil are affected by several sets of factors that consist of genetic factors, environmental conditions, and interactions between environmental and genetic factors (Zahran and Tawfeuk 2019). The occurrence of higher amount of the essential oleic acid and linoleic acids in groundnut and linolenic acid in linseed indicated that the groundnut and linseed oils are highly nutrient (Niamayoua et al. 2015). The groundnut and linseed oils are regarded as oleic-linoleic acid and linolenic oil because of the abundance of those mentioned oils found, respectively. The linseed in the diets increased the stearic acid, without significant difference displaying a positive response given that the stearic acid has no effect on blood cholesterol levels and other vascular and coronary illness risk factors (Atti et al. 2013). Linoleic acid contains anticarcinogenic, antiatherogenic, and antidiabetic modifying qualities that may have positive impacts on health (Gore et al. 2023). According to (Maruba et al., 2018), linolenic acid is rich in omega-3 fatty acids, while linoleic acid is rich in omega-6 fatty acids.

Principal Component Analysis (PCA)

Principal component analysis (PCA) is a multivariate statistical system used for examining the explanation of large datasets and recovering the most useful statistics. It is a size reduction technique using the data set of the investigated oil crops characteristics (Sapkota et al. 2022). The PCA model was applied to all data to identify the significant variables that elucidate the relationships between particular quality characteristics of oil crops to categorize any group patterns (Table 4). All of the total variations have been resulting from two principal component axis and Eigenvalues greater than 1. Variability values (%), cumulative ratio (%), and eigenvalues were illustrated in Table 4.

Table 4.

Eigenvectors and contribution of the first two principal components for groundnut and linseed samples

Parameters Loading values for groundnut Loading values for linseed
PC1 PC2 PC1 PC2
SV 0.477 0.275 0.527 0.175
AV 0.561 0.201 -0.289 -0.154
PV 0.245 0.502 -0.246 0.527
IV 0.701 -0.055 -0.090 -0.329
SG -0.089 -0.354 0.096 -0.328
Moisture 0.046 0.665 0.315 -0.257
Ash -0.305 0.006 -0.229 -0.242
Fibre 0.618 -0.168 0.201 -0.269
Fat -0.269 0.173 0.470 0.189
Protein 0.238 0.531 0.528 0.162
CHO -0.199 -0.280 -0.311 0.092
Na 0.904 -0.028 -0.323 0.004
K -0.131 0.934 -0.040 0.841
Mg 0.802 -0.056 0.466 0.196
Ca -0.014 -0.370 -0.155 0.702
Fe -0.242 0.474 0.034 -0.341
Zn -0.253 0.206 -0.258 0.407
Eigenvalue 10.78 7.27 9.53 8.46
Variance (%) 59.60 40.40 52.97 47.03
Cumulative ratio (%) 59.60 100 52.97 100
Open in a new tab

The PC1 and PC2 explained 59.60% and 40.40% for groundnut, 52.97% and 47.03% variations for linseed samples, respectively. The cumulative ratio of the two primary components accounted for 100% of variation in both oil crops. The first principal component (PC1) having higher contribution factor load from Na (0.904), Mg (0.802), IV (0.701), fibre (0.618), AV (0.561), and SV (0.477) for groundnut and SV (0.527), protein (0.528), fat (0.47), Mg (0.466), and moisture (0.315) for linseed samples. The second principal component (PC2)) described the highest positive factor loads from K (0.934), Fe (0.474), protein (0.531), moisture (0.665), and PV (0.502) for groundnut Fig. 2A and K (0.841), Ca (0.702), Zn (0.407), and PV (0.527) for linseed samples Fig. 2B. The PCA exploration approved for the purpose of this study, thus established significant differences in the chemical composition of oil crops depending on the cultivar. Higher positive loadings in all PCs showed that these metals and physicochemical parameters are likely influenced by factors such as natural composition of the earth’s crust, presence of uncontrolled landfills contribute to the leaching of these metals and other parameters into the agricultural soil. The PCA values confirmed Mg as highest-loading metal (strong in both PC1s) whereas Fe as lowest (weak loadings). Groundnut samples with high PC1 scores are more mineral driven, but potentially acidic while linseed oil is quality focused.

Fig. 2.

Fig. 2

Open in a new tab

Principal component analysis (biplot) showing the relationship among the physicochemical quality properties and analysed metals in groundnut (A) and linseed (B)

Conclusion

Physicochemical characterization, mineral levels and fatty acid profiles of groundnut and linseed from the Gamo Zone, Kamba woreda were examined. For this study, hexane was used to identify the composition of fatty acid profiles for groundnut and linseed. Physicochemical characteristics such as acid value, saponification value, iodine value and peroxide values were in line with the recommended value of edible oils set by FAO/WHO. The average level of minerals decreased in the order as follows: Mg > K > Na > Ca > Zn > Fe for groundnut and Mg > Ca > K > Na > Zn > Fe for linseed samples. From this study, oleic acid, linoleic acid and palmitic acid for groundnut and linolenic acid, linoleic acid, and oleic acid are the major fatty acids identified in linseed whereas octadecanoic acid and eicosanoic acid for groundnut and Palmitic acid for linseed are minor fatty acids. Comparatively, linseed oil contains more fatty acids than groundnuts. In both oil crop samples, two principal components were identified to reduce the dimensionality of complex datasets. PC1 and PC2 together explain a substantial portion of the total variance (> 70%), this indicates strong underlying patterns without needing more components. Apart from having contents of protein, carbohydrate, fat, fibre, and essential minerals, their oils exhibited good physicochemical properties and are rich in essential fatty acids. The chemical composition, physicochemical properties, nutritional values and mineral profiles of groundnut and linseeds suggest that these seeds could be considered as the major sources of good quality oils.

Author Contributions

Mulatu Getachew: Investigation, Formal analysis, Data curation, Methodology, validation Tolera Seda Badessa: Supervision, Conceptualization, Writing-review and editing, validation, Conceptualization, Mamo Dikamu: Conceptualization, Visualization, validation, writing-review and editing, Dessie Ezez: Methodology, Formal analysis, writing original draft, validation.

Funding

No any finical support for the research work and/or publications of articles.

Data Availability

All data used to support the findings were included in the main body of the articles.

Declarations

Competing Interests

The authors declare no competing interests.

Footnotes

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

References

  1. Abebe Y, Tadesse A, Mulugeta G (2023) Soil characteristics and agronomic practices affecting groundnut yield in Ethiopia. Ethiop J Agricultural Sci 22(1):55–67 [Google Scholar]
  2. Abeer AI, Azhari HN, Mahmoud MA, Ibrahim YE, Omer AOI (2020) Physicochemical properties and fatty acids composition of Sudanese baobab (Adansonia digitata L.) seed oil. Int J Pharma Bio Sci 11(1). 10.22376/ijpbs.2020.11.1.p34-42
  3. Aremu MO, Ibrahim H, Bamidele TO (2015) Physicochemical characteristics of the oils extracted from some Nigerian plant Foods – A review. Chem Process Eng Res 32:36–52 [Google Scholar]
  4. Ashong GW, Ababio BA, Kwaansa-Ansah EE (2024) Evaluation of trace metals and quality of selected brands of vegetable cooking oils available on the Ghanaian market. J Trace Elem Minerals 8(2023):100119. 10.1016/j.jtemin.2024.100119 [Google Scholar]
  5. Asibuo JY, Akromah R, Safo-Kantanka O, Adu-Dapaah HK, Ohemeng-Dapaah S, Agyeman A (2008) Chemical composition of groundnut, Arachis Hypogaea (L) landraces. Afr J Biotechnol 7(13):2203–2208. 10.5897/AJB08.113 [Google Scholar]
  6. Atti N, Methlouthi N, Saidi C, Mahouachi M (2013) Effects of extruded linseed on muscle physicochemical characteristics and fatty acid composition of lambs. J Appl Anim Res 41(4):404–409. 10.1080/09712119.2013.792730 [Google Scholar]
  7. Audu Chomo P, Ezekiel Gyang A, Bahago Istifanus J (2023) Chemical Constituents,Proximate Composition, and Heavy Metals of the Oil Seed of Guizotia scabraConsumed in Plateau State-Nigeria. Sci J Anal Chem 11(1):9–12. 10.11648/j.sjac.20231101.12 [Google Scholar]
  8. Azuokwu A, Igbafe A, Yerima Y, Akpobi E, Ngubi F, Azike R, Onoji S (2024) A comparative study of the physicochemical properties of oils extracted from common species of the Niger delta Raphia palm fruits and Elaeis guineensis. Am J Chem Eng 12(3):34–51. 10.11648/j.ajche.20241203.11 [Google Scholar]
  9. Babandi A, Murtala Y, Kabara HT, Abdurasheed A, Yakasai HM, Babagana K, Shehu D, Muhammad A, Ibrahim S, Ibrahim A (2017) Assessment of heavy metal and physicochemical properties of ground nut oil locally processed in Kano, Nigeria. Biol Environ Sci J Tropics 14(3):21–29 [Google Scholar]
  10. Babatunde OA, Bello GS (2016) Comparative assessment of some physicochemical properties of groundnut and palm oils sold within Kaduna metropolis, Nigeria. I. O. S. R. J Appl Chem 9(11):2278–5736 [Google Scholar]
  11. Bayisa YM, Bullo TA (2021) Optimization and characterization of oil extracted from Croton macrostachyus seed for antimicrobial activity using experimental analysis of variance. Heliyon 7(9):1–3 [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Beema N, Mukkamula N, Mothuku S, Thumu R, Azmeera T, Biman KK (2023) Comparative analysis of physico-chemical properties and fatty acid composition of linseed (Linum usitatissimum L.) oils of Indian accessions. J Appl Biology Biotechnol 11(1):80–81 [Google Scholar]
  13. Belete A, Bayissa LD (2020) Proximate and mineral compositions of Raw and roasted groundnut (Arachis Hypogaea L.) obtained from East Hararghe zone. Ethiopia J Sci Sustainable Dev 8(1):26–38. 10.20372/au.jssd.8.1.2020.0140 [Google Scholar]
  14. Beshaw T, Demssie K, Tefera M, Guadie A (2022) Determination of proximate composition, selected essential and heavy metals in Sesame seeds (Sesamum indicum L.) from the Ethiopian markets and assessment of the associated health risks. Toxicol Rep 9:1806–1812. 10.1016/j.toxrep.2022.09.009 [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Christian Ebere E (2019) Proximate and mineral composition of sesamum indicum L. Seed. Med Anal Chem Int J 3(4). 10.23880/macij-16000152
  16. Çiftçi S, Suna G (2022) Functional components of peanuts (Arachis Hypogaea L.) and health benefits: A review. Future Foods 5(2021):100140. 10.1016/j.fufo.2022.100140 [Google Scholar]
  17. Ezez E, Belew M (2023) Analysis of physicochemical attributes, contamination level of trace metals and assessment of health risk in mango fruits from Southern region Ethiopia. Toxicol Rep 10(2022):124–132. 10.1016/j.toxrep.2023.01.004 [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Fan R, Wang L, Cao H, Du R, Yang S, Yan Y, Zheng B (2024) Characterization of the structure and physicochemical properties of soluble dietary fiber from peanut shells prepared by pulsed electric fields with Three-Phase partitioning. Molecules 29(7):1603. 10.3390/molecules29071603 [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Feleke A, Bibiso M, Lelago A (2023) Levels of metals and nutritional composition of garden Cress (Lepidium sativum) Seed, in Southern Ethiopia. Agricultural Sci Digest 43(3):368–372. 10.18805/ag.DF-477 [Google Scholar]
  20. Getachew B, Tadesse A, Merga B (2023) Agro-ecological factors affecting groundnut cultivation in Ethiopia. Ethiop J Agricultural Res 18(2):127–141 [Google Scholar]
  21. Gore VB, Rathod PJ, Vala AG, Bhavitha G, Kumar D (2023) Fatty acid profiling through GC-MS in oil extracted from Thirty varieties of groundnut grown in Gujarat, India. Emergent Life Sci Res 09(01):149–158. 10.31783/elsr.2023.91149158 [Google Scholar]
  22. Hagos M, Yaya EE, Chandravanshi BS, Redi-Abshiro M (2023) Determination of fatty acids composition by Gc-Ms and physicochemical parameters of pumpkin (Cucurbita Maxima) seed oil cultivated in Ethiopia. Bull Chem Soc Ethiop 37(3):565–577. 10.4314/bcse.v37i3.3 [Google Scholar]
  23. Huang Y, Zhang X, Yang H (2022) Health benefits of alpha-linolenic acid: A review of recent research. Nutrients 14(8):1623. 10.3945/ajcn.113.07151435458185 [Google Scholar]
  24. Ibourki M, Ait H, Laila B, El B, Sakar H, Asdadi A (2022) Mineral profiling of Twenty wild and cultivated aromatic and medicinal plants growing in Morocco. Biol Trace Elem Res 200:4880–4889. 10.1007/s12011-021-03062-w [DOI] [PubMed] [Google Scholar]
  25. Idrissi LE, El Guezzane Z, Boujemaa C, Bernoussi IE, Sifou S, El Moudden A, Ullah H, Bari R, Goh A, Goh KW, Bouyahya BH, Harhar A, H., Tabyaoui M (2024) Blending cold-pressed peanut oil with omega-3 fatty acids from walnut oil: analytical profiling and prediction of nutritive attributes and oxidative stability. Food Chemistry: X 22:101453. 10.1016/j.fochx.2024.101453 [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Ishag OAO, Khalid AA, Abdi A, Erwa IY, Omer AB, Nour AH (2019) Proximate composition, physicochemical properties and antioxidant activity of flaxseed. Annual Res Rev Biology 34(2):1–10. 10.9734/ARRB/2019/v34i230148 [Google Scholar]
  27. Jahan S, Bisrat F, Faruque MO, Ferdaus MJ, Khan SS, Farzana T (2021) Formulation of nutrient enriched germinated wheat and mung-bean based weaning food compare to locally available similar products in Bangladesh. Heliyon 7(5):e06974. 10.1016/j.heliyon.2021.e06974 [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Jain R, Singh Head V, professor A, Singh V (2023) Proximate, mineral and anti-nutritional (Cyanogenic glycosides) properties of flaxseed (Linum usitatissimum). ~ 2513 ~ Pharma Innov J 12(6):2513–2515. https://www.agmrc.org/commodities- [Google Scholar]
  29. Jalil D, Waleed L, Abdulwhaab S, Abid A (2022) Health risk study of heavy metals from consumption of drugs (Solid and Liquid) samples derived from medicinal plants in Iraq. Biol Trace Elem Res 201:3528–3540. 10.1007/s12011-022-03408-y [DOI] [PubMed] [Google Scholar]
  30. Jones P, Peterson T, Ho T (2021) Linseed oil: an overview of its production and health benefits. J Nutr Biochem 93:108–119 [Google Scholar]
  31. Karahan F (2022) Evaluation of trace element and heavy metal levels of some ethnobotanically important medicinal plants used as remedies in Southern Turkey in terms of human health risk. Biol Trace Elem Res 201:493–513. 10.1007/s12011-022-03299-z [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Kassaw G, Badessa TS, Ezez D (2023) Mineral contents and health risk assessment of Sesame (Sesamum indicum Linn) seeds grown in Ethiopia. J Food Compos Anal 123:105562. 10.1016/j.jfca.2023.105562 [Google Scholar]
  33. Khadra B, Ahmed M, Somia B, Ahmed B, Nafissa B, Nassima F (2022) Physicochemical properties of balanites aegyptiaca’s seeds and seed oil from Southern Algeria. Egypt J Chem 65(10):39–45. 10.21608/EJCHEM.2022.98766.4596 [Google Scholar]
  34. Kris-Etherton PM, Harris WS, Appel LJ (2021) Omega-3 fatty acids and cardiovascular disease: new evidence, continued controversy. J Am Coll Cardiol 58(20):45–60. 10.1016/j.jacc.2011.06.063 [DOI] [PubMed] [Google Scholar]
  35. Kumar B, Sadagopan RS, Vasanthi P, Kalapati R, M., Vishnuvardhan M (2013) Comparative physico-chemical, proximate and mineral analysis on Raw and roasted seeds of groundnut. Commun Plant Sci 3:3–4 [Google Scholar]
  36. Lumpur K (2019) Joint FAO/WHO food standards programme codex committee on fats and oils 26 th Session recommended methods of analysis and sampling codex stan 234–1999
  37. Maruba P, Jamaran K, Basuki W, Jansen S (2018) Determination and identification of Omega 3 and 6 fatty acids position in nile tilapia oil. Earth Environ Sci 205(1):012045. 10.1088/1755-1315/205/1/012045 [Google Scholar]
  38. Mekebo D, Chandravanshi BS (2014) Levels of essential and non-essential metals in linseed (linum usitatissimum) cultivated in Ethiopia. Bull Chem Soc Ethiop 28(3):349–362. 10.4314/bcse.v28i3.4 [Google Scholar]
  39. Mengistie T, Alemu A, Mekonnen A (2018) Comparison of physicochemical properties of edible vegetable oils commercially available in Bahir Dar, Ethiopia. Chem Int 4(2):130–135 [Google Scholar]
  40. Meta MG (2018) Extraction and physicochemical characterization of oil from Maringa stenopetala seeds. IOSR J Appl Chem 11(6):1–7. 10.9790/5736-1106010107 [Google Scholar]
  41. Micha R, Peñalvo JL, Cudhea F, Imamura F (2023) Dietary fats and health: new evidence and current controversies. JAMA 329(2):112–124 [Google Scholar]
  42. Mora-Escobedo R, Hernández-Luna P, Joaquín-Torres IC, Ortiz-Moreno A, Robles-Ramirez MDC (2015) Physicochemical properties and fatty acid profile of eight peanut varieties grown in Mexico. CYTA - J Food 13(2):300–304. 10.1080/19476337.2014.971345 [Google Scholar]
  43. Musa M (2017) Fatty acid Composition, Tocopherol and sterol contents in linseed (Linum usitatissimum L.) varieties. 36(3):147–152
  44. Musalima JH, Ogwok P, Mugampoza D (2019) Fatty acid composition of oil from groundnuts and oyster nuts grown in Uganda. J Food Res 8(6):37. 10.5539/jfr.v8n6p37 [Google Scholar]
  45. Nagrale SC, An P, Tayade N, Pv J, Ys W (2018) Proximate composition and Estimation of mineral content from different Mungbean (Vigna radiata (L).Wliczek) genotypes. J Pharmacognosy Phytochemistry 7(4):3434–3436. https://www.nlm.nih.gov/ [Google Scholar]
  46. Niamayoua RK, Nsikabaka S, Ossoko JPL, Enzonga J, Djimi LS, Silou T, Desobry S, Bioprocédés L, De, Biomolécules I, De LE, De, De A, De Haye F (2015) Nutritional Value of Manga Groundnut (Arachis hypogea) and Characterization of Oil Extracted by Solvent. 7(12):914–920. 10.19026/ajfst.7.2533
  47. Olajuyigbe AA, Amah GH, Adebawo OO, Olajuyigbe OO (2019) Extraction and GC-MS analysis of the fatty acids in commonly consumed melon seed varieties in Nigeria. GSC Biol Pharm Sci 7(3):077–092. 10.30574/gscbps.2019.7.3.0086 [Google Scholar]
  48. Olaoye AB, Oladejo AA, Ishaya FA (2021) Determination of Physico-chemical Properties, cholesterol and vitamin A levels of vegetable oils commonly sold in ado Ekiti metropolis. Eur J Nutr Food Saf 13(5):53–56 [Google Scholar]
  49. Opaluwa OD, Aremu MO, Ogbo LO, Abiola KA, Odiba IE, Abubakar MM, Nweze N (2012) Heavy metal concentrations in soils, plant leaves and crops grown around dump sites in Lafia Metropolis, Nasarawa State, Nigeria. Adv Appl Sci Res 3(2):780–784 www.pelagiaresearchlibrary.com [Google Scholar]
  50. Oyeyinka SA, Agabje RO, Babayeju AA, Opaleke DO, Kolawole FL, Badmos AA, Njobeh PB, Adebo OA (2024) Consumer perception and physicochemical properties of crude groundnut oil in comparison with selected vegetable oil. Discover Food 4(1):50. 10.1007/s44187-024-00118-3 [Google Scholar]
  51. Ozyigit II, Karahan F, Ertugrul I, Asli Y, Ozyigit H, Ilcim A (2022) Heavy metals and trace elements detected in the leaves of medicinal plants collected in the Southeast part of Turkey. Arab J Geosci 15:27. 10.1007/s12517-021-09264-9 [Google Scholar]
  52. Pandurangan MK, Murugesan S, Gajivaradhan P (2014) Physicochemical properties of groundnut oil and their blends with other vegetable oils. J Chem Pharm Res 6(8):60–66
  53. Parameshwari S, Nazni P (2015) Physicochemical and Nutrient Analysis of Linseed (Linum Usitatissimum) Powder. 392–395
  54. Pardeshi S (2019a) Assessment of proximate composition of groundnut seeds and characterization of their extracted oils from different varieties grown in India. Int Res J Eng Technol 6(8):854–860 [Google Scholar]
  55. Pardeshi S (2019b) Proximate composition of groundnut seeds and physicochemical composition of their extracted oils from different groundnut varieties grown in India. Int Adv Res J Sci Eng Technol 6(9):25–32. 10.17148/IARJSET.2019.6903 [Google Scholar]
  56. Peirovi-Minaee R, Alami A, Esmaeili F, Zarei A (2024) Analysis of trace elements in processed products of grapes and potential health risk assessment. Environ Sci Pollut Res 31(16):24051–24063. 10.1007/s11356-024-32654-x [DOI] [PubMed] [Google Scholar]
  57. Puwastien P, Siong TE, Kantasubrata J, Craven G, Feliciano RR, Judprasong K (2011) Manual of food analysis. Aseanfoods, 188. www.inmu.mahidol.ac.th/aseanfoods
  58. Qiu C, Wang H, Guo Y, Long S, Wang Y, Mehmood A, Guo X, Jarvis DI (2020) Comparison of fatty acid composition, phytochemical pro Fi Le and antioxidant activity in four Fl ax (Linum usitatissimum L.) varieties. Oil Crop Sci 5(3):136–141. 10.1016/j.ocsci.2020.08.001 [Google Scholar]
  59. Raigar RK, Upadhyay R, Mishra HN (2017) Optimization of microwave roasting of peanuts and evaluation of its physicochemical and sensory attributes. J Food Sci Technol 54(7):2145–2155. 10.1007/s13197-017-2654-0 [DOI] [PMC free article] [PubMed] [Google Scholar]
  60. Sanni JA, Sanni GO, Awoniyi RR, Osanyinlusi R, Richards YE, Adesina GI, Adenuga OO, Apata SA, Ekun OE (2024) Effects of processing on the proximate Composition, mineral content and the phytochemical analysis of groundnut seeds (Arachis hypogeae). Biology Med Nat Prod Chem 13(1):63–71. 10.14421/biomedich.2024.131.63-71 [Google Scholar]
  61. Sapkota BK, Khadayat K, Sharma K, Raut BK, Aryal D, Thapa BB, Parajuli N (2022) Phytochemical analysis and antioxidant and antidiabetic activities of extracts from Bergenia ciliata, mimosa pudica, and phyllanthus emblica. Adv Pharmacol Pharm Sci 2022. 10.1155/2022/4929824 [DOI] [PMC free article] [PubMed]
  62. Shawhatsu NM (2022) Variation of refractive index with physical properties of groundnut oil. Int J Adv Eng Manage 4(6):1624–1625 [Google Scholar]
  63. Shiferaw Y, Kassahun A, Tedla A, Feleke G, Abebe AA (2019) Investigation of essential oil composition variation with age of Eucalyptus globulus growing in Ethiopia. Nat Prod Chem Res 07(02). 10.35248/2329-6836.19.7.360
  64. Smith R, Jones P, Johnson L (2023) Linseed oil: Production, quality, and health benefits. J Agric Food Chem 71(4):951–967 [Google Scholar]
  65. Sokoła-Wysoczańska E, Wysoczański T, Wagner J, Czyż K, Bodkowski R, Lochyński S, Patkowska-Sokoła B (2018) Polyunsaturated fatty acids and their potential therapeutic role in cardiovascular system disorders: A review. Nutrients 10(10):1561. 10.3390/nu10101561 [DOI] [PMC free article] [PubMed] [Google Scholar]
  66. Sufiyanu S, Na’ala SI (2022) Physico-chemical analysis of oil from two cultivars of groundnut seeds (Arachis hypogea L). Dutse J Pure Appl Sci 8(1):87–92. 10.4314/dujopas.v8i1a.9 [Google Scholar]
  67. Suri K, Singh B, Kaur A, Yadav MP (2023) Physicochemical characteristics, oxidative stability, pigments, fatty acid profile and antioxidant properties of co-pressed oil from blends of peanuts, flaxseed and black Cumin seeds. Food Chem Adv 2:100231. 10.1016/j.focha.2023.100231 [Google Scholar]
  68. Taghavi M, Darvishiyan M, Momeni M, Eslami H, Fallahzadeh RA, Zarei A (2023) Ecological risk assessment of trace elements (TEs) pollution and human health risk exposure in agricultural soils used for saffron cultivation. Sci Rep 13(1):4556. 10.1038/s41598-023-31681-x [DOI] [PMC free article] [PubMed] [Google Scholar]
  69. Tanska M, Sylwester C, Tadeusz S, Bogumił R, Marta K, Zofia A, Iwona K (2025) Variation in linseed oil composition: impact of Cultivar, cultivation System, and year of cultivation. Molecules 30:875. 10.3390/molecules30040875 [DOI] [PMC free article] [PubMed] [Google Scholar]
  70. Tefera M, Aderajew H, Ezez D, Dikamu M, Lakew W (2025) Holistic approach to assess human health risks, integrating physicochemical quality attributes and heavy metal levels in tap water. Toxicol Rep 15:102121. 10.1016/j.toxrep.2025.102121 [DOI] [PMC free article] [PubMed] [Google Scholar]
  71. Wazed M, Yasmin S, Basak P, Hossain A, Rahman M, Hasan M, Khair M, Khatun M (2023) Evaluation of physicochemical parameters of edible oils at room temperature and after heating at high temperature. Food Res 7(4):91–94 [Google Scholar]
  72. Xiao Y, Liu H, Lu Q, Li H, Liu Q, Li S, Liu H, Varshney RK, Liang X, Hong Y, Chen X (2022) Lipid profile variations in high Olecic acid peanuts by following different cooking processes. Food Res Int 155:110993. 10.1016/j.foodres.2022.110993 [DOI] [PubMed] [Google Scholar]
  73. Yuenyong J, Pokkanta P, Phuangsaijai N, Kittiwachana S, Mahatheeranont S, Sookwong P (2021) GC-MS and HPLC-DAD analysis of fatty acid profile and functional phytochemicals in Fifty cold-pressed plant oils in Thailand. Heliyon 7(2):e06304. 10.1016/j.heliyon.2021.e06304 [DOI] [PMC free article] [PubMed] [Google Scholar]
  74. Zafar SH, Umair M, Akhtar M (2023) Nutritional evaluation, proximate and chemical composition of Mungbean varieties/cultivars pertaining to food quality characterization. Food Chem Adv 2(2022):100160. 10.1016/j.focha.2022.100160 [Google Scholar]
  75. Zahran HA, Tawfeuk HZ (2019) Physicochemical properties of new peanut (Arachis Hypogaea L.) varieties. OCL - Oilseeds Fats Crops Lipids 26(2). 10.1051/ocl/2019018
  76. Zeleke Tilinti B, Ayichiluhim B, Mekonnen Tura T, A., Duraisamy R (2023) Extraction and characterizations of Omega 3-fatty acid from Cat fish collected from Arba minch Chamo lake. Cogent Food Agric 9(1):2216042. 10.1080/23311932.2023.2216042 [Google Scholar]
  77. Zhang W, Yang T, Li S (2023) Fatty acids and their role in skin health: mechanisms and applications. J Cosmet Dermatol 22(1):123–135 [Google Scholar]
  78. Zhang W, Yang T, Li S (2024) The role of fatty acids in skin health and protection. J Cosmet Dermatol 23(2):212–225 [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

All data used to support the findings were included in the main body of the articles.

Articles from Biological Trace Element Research are provided here courtesy of Springer

RESOURCES