J. Biosci. Agric. Res. | Volume 33, Issue 01, 2675-2683 | https://doi.org/10.18801/jbar.330124.322
Article type: Research article | Received: 02.04.2024; Revised: 10.05.2024; First published online: 25 May 2024.
Article type: Research article | Received: 02.04.2024; Revised: 10.05.2024; First published online: 25 May 2024.
Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit
Md. Mohidul Hasan 1, Israt Jahan 2, Md. Rishad Abdullah 3, Mohammad Rezaul Karim 4, Md. Mehbub Hasan 3, Mst. Zinnatun Nesha 4 and Kazi Tanzila Akter Banna 4
1 Dept. of Planning, Bangladesh Jute Research Institute, Manik Mia Avenue, Dhaka-1207, Bangladesh.
2 Genome Research Centre, Bangladesh Jute Research Institute, Manik Mia Avenue, Dhaka-1207, Bangladesh.
3 Jute Research Regional Station, Bangladesh Jute Research Institute, Rangpur-5403, Bangladesh.
4 College of Agricultural Sciences, International University of Business Agriculture and Technology, Dhaka, Bangladesh.
✉ Corresponding author: [email protected] (Hasan, MM).
1 Dept. of Planning, Bangladesh Jute Research Institute, Manik Mia Avenue, Dhaka-1207, Bangladesh.
2 Genome Research Centre, Bangladesh Jute Research Institute, Manik Mia Avenue, Dhaka-1207, Bangladesh.
3 Jute Research Regional Station, Bangladesh Jute Research Institute, Rangpur-5403, Bangladesh.
4 College of Agricultural Sciences, International University of Business Agriculture and Technology, Dhaka, Bangladesh.
✉ Corresponding author: [email protected] (Hasan, MM).
Abstract
Kenaf (Hibiscus cannabinus L.) is a versatile plant belonging to the Malvaceae family. Historically valued for its fiber, Kenaf has gained attention for its nutritional and medicinal properties. The study aimed to analyze the nutritional composition of Kenaf seed oil and to assess edible application of Kenaf seed oil. Addressing the study objectives, the study was conducted at three different laboratories from February 2024 to May 2024. Potential Edible Application and Nutritional Benefits from kenaf seed oil were analyzed by considering essential fatty acid, specific gravity, and total tocopherol. There were 9 essential fatty acids found like C14:0 (Myristic acid) 0.15%; C16:0 (Palmitic acid) 20.29%, C16:1 (Palmitoleic acid) 0.61%, C17:0 (Heptadecanoic acid) 0.06%, C18:0 (Stearic acid) 1.40%, C18:1 (Oleic acid) 27.44%, C18:2 (Linoleic acid) 49.43%, a polyunsaturated fatty acid C18:3 (Linolenic acid) 0.47% and C24:0 (lignoceric acid) 0.14%. The specific gravity of the sample at 30°C was 0.9124 g/ml. Vitamin E which were found as Alpha Tocopherol (43 mg/100g), Gamma Tocopherol (31.23 mg/100g) and Delta Tocopherol (2.83 mg/100g). These nutritional and functional properties of the kenaf will be helpful for further research, development and application in various industries in connection to food, cosmetics, pharmaceuticals and health issues.
Key Words: Kenaf, Oil, Seed, Fatty acid and Tocopherol
Kenaf (Hibiscus cannabinus L.) is a versatile plant belonging to the Malvaceae family. Historically valued for its fiber, Kenaf has gained attention for its nutritional and medicinal properties. The study aimed to analyze the nutritional composition of Kenaf seed oil and to assess edible application of Kenaf seed oil. Addressing the study objectives, the study was conducted at three different laboratories from February 2024 to May 2024. Potential Edible Application and Nutritional Benefits from kenaf seed oil were analyzed by considering essential fatty acid, specific gravity, and total tocopherol. There were 9 essential fatty acids found like C14:0 (Myristic acid) 0.15%; C16:0 (Palmitic acid) 20.29%, C16:1 (Palmitoleic acid) 0.61%, C17:0 (Heptadecanoic acid) 0.06%, C18:0 (Stearic acid) 1.40%, C18:1 (Oleic acid) 27.44%, C18:2 (Linoleic acid) 49.43%, a polyunsaturated fatty acid C18:3 (Linolenic acid) 0.47% and C24:0 (lignoceric acid) 0.14%. The specific gravity of the sample at 30°C was 0.9124 g/ml. Vitamin E which were found as Alpha Tocopherol (43 mg/100g), Gamma Tocopherol (31.23 mg/100g) and Delta Tocopherol (2.83 mg/100g). These nutritional and functional properties of the kenaf will be helpful for further research, development and application in various industries in connection to food, cosmetics, pharmaceuticals and health issues.
Key Words: Kenaf, Oil, Seed, Fatty acid and Tocopherol
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I. Introduction
Kenaf (Hibiscus cannabinus L.), an annual herbaceous plant belonging to the Malvaceae family, is widely distributed across Asia and Africa, thriving mainly in temperate to tropical regions (Zawawi et al., 2014). The Malvaceae family is known for its economic and horticultural significance (Akinrotimi & Okocha, 2018). Kenaf, which belongs to the genus Hibiscus, includes more than 200 species, both annual and perennial (Hassan et al., 2018). This versatile plant can grow under diverse weather conditions, reaching heights of 2.5 to 4.5 meters with a woody base. As one of the most important fiber crops globally, kenaf is composed of various valuable components, including stalks, leaves, and seeds, which provide fibers, fiber strands, proteins, oils, and allelopathic chemicals (Akinrotimi & Okocha, 2018). These components enable the production of numerous products, supporting continuous use and development (Mostafa et al., 2013).
Traditionally considered waste after losing viability in storage, kenaf seeds have been found to contain significant amounts of antioxidant-rich oil (Chan & Ismail, 2009; Ryu et al., 2017). This unique composition has led to the use of kenaf seed oil as an alternative edible oil for human consumption (Chan & Ismail, 2009; Cheng et al., 2016; Mariod et al., 2010; Mohamed et al., 1995). Natural antioxidants in kenaf seed oil may offer protective benefits against cancer (Wing et al., 2016). Additionally, kenaf seeds have been consumed to aid in weight gain and bruise healing (Alexopoulou et al., 2013). The plant exhibits various medicinal properties, including analgesic, aperitif, aphrodisiac, anti-inflammatory, and antioxidant effects, particularly in its leaves and seeds. It has also been associated with benefits such as weight gain, anemia treatment, and fatigue reduction (Kobaisy et al., 2001; Khare, 2007; Kubmarawa et al., 2009; Alexopoulou et al., 2013). Given its abundance and promising nutritional attributes, exploring kenaf seed oil's potential as an edible oil could diversify agricultural applications and contribute to healthier dietary options (Coetzee et al., 2008).
Plant seeds have historically served as vital sources of oils for dietary, medicinal, and industrial purposes, often obtained as valuable by-products from industrial fruit processing. Efficient pre-extraction and extraction processes are crucial for recovering bioactive components from plant materials. Optimizing these processes can enhance the yield and quality of essential oils, maximizing their commercial value and expanding their applications across various sectors (Daud et al., 2022). This research proposal outlines a systematic plan to observe and evaluate the nutritional composition and assess the edible application of kenaf seed oil.
II. Materials and Methods
Study location
The experiment was conducted in the laboratory of the Department of Breeder Seed, Bangladesh Jute Research Institute, Dhaka; Centre for Advanced Research in Sciences (CARS), University of Dhaka and WAFFEN Research Laboratory Limited from February 2024 to May 2024.
Materials used
Kenaf (Hibiscus cannabinus L.) variety HC-95 was released in 1995 (Figure 01) and collected from Jute Research Regional Station, Rangpur.
Step-1 Collection of Kenaf seed
Step-2 Extraction of kenaf seed oil
Step-3 Analysis of extracted kenaf seed oil
Figure 01. Kenaf seed sample Figure 02. Flowchart diagram of experimental design
Design of experiment
There were three steps followed for this experiment. The flow chart diagram is shown in Figure 02.
Procedures of extraction
Kenaf seeds have high oil content and are extracted through several methods. For this experiment, use solvent extraction method.
Seed weighting: Accurate measurement of the seed weight ensures consistency in the extraction process. In this case, 200 grams of seeds were chosen for extraction, but the quantity can vary based on the desired yield (Figure 03).
Drying: Drying the seeds helps to remove any moisture present, which could interfere with the extraction process. Typically, seeds were dried using air or oven drying methods until they reached a specified moisture content (Figure 04).
Figure 03. Measuring seed weights Figure 04. Drying Figure 05. Powder of kenaf seed
Grinding: The dried seeds were ground into a fine powder using a mechanical grinder or mill. Grinding increases the surface area of the seeds, enhancing the extraction efficiency by allowing better contact between the solvent and the seed material (Figure 05).
Mixing with solvent: Half of the ground powder (100 gm) was mixed with a solvent mixture containing 200 ml of hexane and 100 ml of water. Hexane was a common solvent used for extracting oils from seeds due to its ability to dissolve non-polar compounds like oils. The addition of water helps separate impurities and polar components from oil (Figure 06).
Extraction with Hexane
The prepared seed powder was conveyed to an extractor. In the extractor, the seed powder was exposed to hexane solvent. Hexane was chosen as a solvent because it selectively dissolves the oil present in the seeds. The seed powder was mixed with 200 ml hexane and 100 ml water.
Figure 6. Hexane mixed with powder
Figure 07. Hexane mixed with powder (Resting period)
Figure 08. Separating hexane from the mixture Figure
09. Hexane Evaporation
Resting period: After mixing, the mixture was allowed to rest for 2 hours. During this time, the hexane dissolved the oil present in the seeds, forming a mixture called miscella (Figure. 07).
Separation of miscella: After the resting period, the mixture of hexane and oil (miscella) was obtained. The liquid part (miscella) was separated from the solid residue (seed powder) using a pipette or other suitable means. The miscella, containing the dissolved oil, was collected for further processing (Figure 08).
Hexane Evaporation: The hexane-oil mixture obtained from the separation step was transferred to a suitable container, such as a beaker. The hexane was allowed to evaporate from the mixture, leaving behind the oil in the beaker. Evaporation could be facilitated by applying gentle heat or allowing the mixture to sit room temperature, depending on the volatility of hexane (Figure 09).
Oil collection from mixture
Once the hexane had completely evaporated, the oil residue left in the beaker was collected. The oil collected was the desired product of the extraction process and could be further processed or used as needed. This process ensures that the oil was efficiently extracted from the seeds using hexane as a solvent and then separated from the solvent for final collection.
Parameters tested for edible application
Determination of fatty acid composition ,
Fatty acid methyl ester (FAMEs) preparation: The fatty acid composition was determined by the conversion of oil to fatty acid methyl esters prepared by adding 30mg of oil followed by 3ml of Methanolic KOH (0.5N) and 2ml of Boron trifluoride methanol complex according to the method of AOAC 969.33 & 969.22 with some modifications. The mixtures were cooled, then 20ml saturated Sodium chloride solution was added and 15 minutes for settling. The upper phase containing the FAMEs was recovered by adding 8 ml of n-hexane and analyzed by Gas chromatography (GC- FID). 1 µl samples were injected into the Gas Chromatograph following standard conditions.
The percentage of fatty acid was calculated based on the peak area ratios of fatty acid species to the total peak area of all the fatty acids in the oil sample. The results were expressed in percentages (%). Fatty Acids are calculated individually by the following formula:
Individual Fatty acids %
=(Aera of sample component ×Concentration of standard component ×100)/(Aera of standard component)
Determination of specific gravity
The specific gravity content was determined according to the AOAC method , (AOAC 920.212). The sample was filter through a filter paper to remove any impurities and the last traces of moisture. Make sure that the sample is completely dry. Cool the sample to 30°C or ambient temperature desired for determination. The dry pycnometer was filled with the prepared sample in such a manner to prevent entrapment of air bubbles after removing the cap of the side arm. The stopper was inserted. The pycnometer was immersed in water bath at 30±2.0°C and held for 30 min. Carefully wiped off any oil that had come out of the capillary opening was carefully wiped off. The bottle was removed from the bath, cleaned and dried thoroughly. The cap of the side arm was removed and quickly weighed ensuring that the temperature did not fall below 30°C. Calculations were done with the following equation:
Specific Gravity at 30°C (g/ml)=(A-B)/(C-B)
Where,
A = weight in g of specific gravity bottle with oil at 30°C
B = weight in g of specific gravity bottle at 30°C
C = weight in g of specific gravity bottle with water at 30°C
Determination of Vitamin-E Test
Chromatographic condition:
Column: RP-C18 (Acclaim TM 120, 5µm, 150 × 4.6 mm)
Mobile phase: Methanol (100%)
UV detection: 292 nm
Injection volume: 20 μl
Flow rate: 1.0 ml/min
Run time: 10 mins
Sample Preparation
Accurately 0.5 g of oil sample was weighed in a brown 250 ml round bottom flask. 1 g of L-ascorbic acid was added. 50 ml of Ethanol (Absolute) was added, then 15 ml of 50% KOH was added. Saponification was performed using reflux condenser. Successful saponification was indicated by the disappearance of fatty drops. The sample was rinsed from a flask with 50 ml Ethanol and transferred into a 250 ml separating funnel. 120 ml water was added (breaking emulsion), then extraction was made with a total of 150 ml n-hexane. Hexane phase was washed with water until the KOH was cleared out from the hexane extract and the washings were drained off. Hexane phase was rotary evaporated at 50 °C at 260 mbar. The residue was dissolved in 10 ml of Methanol (HPLC Grade) and injected 20µl into the HPLC system.
III. Results and Discussion
Determination of fatty acid composition
A total of 21 fatty acids were analyzed, with 9 being detected and quantified (Table 01). The most abundant fatty acid was linoleic acid (C18:2), which constituted 49.43% of the total fatty acid content surpassing the levels reported by others [Mohamed et al. (1995): 42.0% to 50.1%, Karim et al. (2021): 29.97% to 31.21%, Ryu et. al. (2013): 36.35% to 39.35%)]. However linolenic acid content of 0.47%, which is consistent with the findings of Mohamed et al. (1995) and Ryu et. al. (2013), who reported ranges of 0.4% to 1.1% and 0.23% to 0.43% respectively for linolenic acid in KSO.
The level of myristic acid in the kenaf seed oil (KSO) sample was less than what was reported by Mohamed et al. (1995), who observed myristic acid levels ranging from 0.30% to 0.79%. Orsavova et al. (2015) noted 0.09% myristic acid in sunflower oil and 0.39% in rice bran oil. However, Frančáková et al. (2015) did not detect any myristic acid in sesame or olive oil.
The oil sample showed a palmitic acid level of 20.29%. This corresponds closely to the findings of Mohamed et al. (1995), who reported palmitic acid levels ranging from 18.6% to 21.4% in kenaf seed oil. However, Karim et al. (2021) and Ryu et. al. (2013) observed significantly higher levels of palmitic acid in kenaf seed oil, ranging from 26.49% to 26.93% and 32.77% to 34.97% respectively. The test KSO showed a palmitoleic acid content of 0.61%. Karim et al. (2021) also noted palmitoleic acid levels of 0.38% to 0.42% in KSO. However, Mohamed et al. (1995) reported a higher amount of palmitoleic acid in their study, ranging from 1.3% to 2.1%. Additionally, common vegetable oils contain lower amounts of palmitoleic acid, as indicated by Orsavova et al. (2015) (sunflower oil: 0.12%, sesame oil: 0.11%, rice bran oil: 0.19%).
The extracted KSO contained 0.06% heptadecanoic acid, a value closely resembling that reported by Karim et al. (2021) (0.04%). Likewise, Orsavova et al. (2015) stated that sunflower oil contains 0.02% heptadecanoic acid. The test sample contained 1.40% stearic acid. In comparison, Mohamed et al. (1995) reported stearic acid levels ranging from 2.0% to 4.0%, Karim et al. (2021) reported 2.70% to 3.64%, and Ryu et. al. (2013) noted 3.06% to 3.16% in their studies. However, other vegetable oils contain higher amounts of stearic acid, such as sunflower oil with 2.8% (Orsavova et al. 2015), and soybean oil with 4.07% (Chowdhury et al., 2007).
The tested KSO exhibited a 27.44% oleic acid content. This aligns with the findings of Mohamed et al. (1995) and Ryu et. al. (2013), who reported oleic acid levels ranging from 24.8% to 34.1% and 26.32% to 29.87%, respectively. However, Karim et al. (2021) observed higher oleic acid levels, ranging from 31.41% to 36.19% in KSO. Comparatively, other vegetable oils contain higher amounts of oleic acid, such as sunflower oil with 45.39% (Chowdhury et al., 2007), sesame oil with 40.75% (Frančáková et al., 2015). The tested KSO exhibited a lignoceric acid content of 0.14%, which is in line with the findings of Mohamed et al. (1995) (0.6% to 0.18%) and Karim et al. (2021) (0.09% to 0.11%). Similarly, sesame oil reported 0.09% lignoceric acid (Frančáková et al., 2015).
The analysis did not detect the presence of several fatty acids, including C6:0, C8:0, C10:0, C12:0, C17:1, C20:0, C20:1, C20:2, C22:0, C22:1, C22:2, and C24:1, indicating that their concentrations, if present, were below the detection limits of the analytical method employed. These findings highlight the potential nutritional value of kenaf seed oil, particularly due to its high content of linoleic and oleic acids, which are essential fatty acids with significant health benefits.
The composition suggests potential health implications, as unsaturated fatty acids are generally healthier than saturated ones. The ratio of omega-6 to omega-3 fatty acids (linoleic acid to linolenic acid) is important for assessing nutritional quality, with an optimal ratio of around 4:1.
Table 01. Determination of fatty acid composition from kenaf seed extract.
Analysis of tocopherol and specific gravity
Specific gravity
The specific gravity of the sample at 30°C was measured at 0.9124 g/ml. Specific gravity is a measure of the density of a substance compared to the density of a reference substance (usually water). This parameter can provide insights into the purity, concentration, or composition of the sample. In this case, it indicates the density of the substance at a specific temperature, which can be useful for various applications, including quality control and formulation (Table 02).
Total tocopherol
Tocopherols are a group of vitamin E compounds with antioxidant properties. The total tocopherol content in the test sample of KSO oil was measured at 77.07 mg/100g using High-Performance Liquid Chromatography (HPLC) (Table 02). This exceeds the values reported by Chew et al. (2016) (62.25-67.33 mg/100g), Chew et al. (2017a) and Chew et al. (2017b) (51.3–64.1 mg/100g), and Nyam and Lau (2015) (38.8 mg/100g) for total tocopherol per 100 g of kenaf seed oil. In terms of total tocopherol content, sunflower oil contains 80.6-85.2 mg/100g (Gliszczyńska-Świgło et al., 2007)) and soybean oil contains 81.7-84.1 mg/100g (Gliszczyńska-Świgło et al., 2007). This parameter reflects the overall concentration of tocopherols present in the sample, which is crucial for assessing its antioxidant activity and potential health benefits.
Alpha Tocopherol
Among the tocopherol compounds, α-tocopherol content in the test sample of KSO was measured at 43 mg/100g (Table 02). This is notably higher compared to findings from previous studies. For instance, Chew et al. (2016) reported a range of 12.14-16.72 mg/100g, while Chew et al. (2017a) and Chew et al. (2017b) found a range of 12.2–21.9 mg/100g. Nyam and Lau (2015) found even lower levels at 6.4-7.2 mg/100g α-tocopherol in KSO. In contrast, Gliszczyńska-Świgło et al. (2007) observed higher amounts of α-tocopherol (56.4-58.6 mg/100 g) in sunflower oil. Alpha-tocopherol is the most biologically active form of vitamin E and is known for its antioxidant properties. Its concentration in the sample indicates the presence of this vital compound, which contributes significantly to the sample's antioxidant capacity and potential health effects.
Beta Tocopherol and
The test sample of KSO oil showed a β-tocopherol content of 31.23 mg/100g (Table 02). This contrasts sharply with the findings of Chew et al. (2017a) and Chew et al. (2017b) who reported a much lower range of 6.4-6.8 mg/100g of β-tocopherol in KSO. Rafalowski et al. (2008) noted higher levels, observing 18.5 mg of β-tocopherol per 100 g of sunflower oil and 18.7 mg per 100 g of soybean oil. Desai et al. (1988) found a range of 0.5-2.9 mg of β-tocopherol per 100 g of rice bran oil, with only trace amounts in olive oil.
Table 02. Analysis of specific gravity and total Tocophrol in kenaf seed oil
Gama Tocopherol
The γ-tocopherol content in the test sample of KSO oil was measured at 31.23 mg/100g (Table 02). This falls within the range reported by Nyam and Lau (2015), who found 26.4-31.6 mg of γ-tocopherol per 100g of kenaf seed oil. Other studies yielded varying results, such as Chew et al. (2017a) , Chew et al. (2017b) reporting 17.8–27.2 mg/100g and Chew et al. (2016) reporting 46.52-54.18 mg/100g of γ-tocopherol in KSO. Carpenter (1979) documented γ-tocopherol levels of 3.8-3.9 mg/100g in sunflower oil, 91.0-93.8 mg/100g in soybean oil, and 1.9-2.1 mg/100g in olive oil.
Delta-tocopherol
The δ-tocopherol content in the test sample of kenaf seed oil was measured at 2.84 mg/100g. While its concentration is lower than other tocopherol forms, it still contributes to the sample's antioxidant capacity. This finding aligns with the results of Chew et al. (2017a), Chew et al. (2017b) and Nyam and Lau (2015), who reported ranges of 1.3–2.5 mg/100g and 2.9-3.1 mg/100g of δ-tocopherol in kenaf seed oil, respectively. Gliszczyńska-Świgło et al., (2007) observed δ-tocopherol levels of 2.90-3.10 mg/110g in sunflower oil and 17.9-18.5 mg/100g in soybean oil. Delta-tocopherol, along with the other tocopherol forms, collectively enhances the sample's stability and shelf life by protecting it from oxidative damage (Table 02).
IV. Conclusion
Overall, the analysis provides comprehensive information about the specific gravity and tocopherol composition of the sample, which are essential for evaluating its quality, nutritional value, and potential health benefits. These results can guide further research, development, and application of the sample in various industries, including food, cosmetics, and pharmaceuticals.
Kenaf (Hibiscus cannabinus L.), an annual herbaceous plant belonging to the Malvaceae family, is widely distributed across Asia and Africa, thriving mainly in temperate to tropical regions (Zawawi et al., 2014). The Malvaceae family is known for its economic and horticultural significance (Akinrotimi & Okocha, 2018). Kenaf, which belongs to the genus Hibiscus, includes more than 200 species, both annual and perennial (Hassan et al., 2018). This versatile plant can grow under diverse weather conditions, reaching heights of 2.5 to 4.5 meters with a woody base. As one of the most important fiber crops globally, kenaf is composed of various valuable components, including stalks, leaves, and seeds, which provide fibers, fiber strands, proteins, oils, and allelopathic chemicals (Akinrotimi & Okocha, 2018). These components enable the production of numerous products, supporting continuous use and development (Mostafa et al., 2013).
Traditionally considered waste after losing viability in storage, kenaf seeds have been found to contain significant amounts of antioxidant-rich oil (Chan & Ismail, 2009; Ryu et al., 2017). This unique composition has led to the use of kenaf seed oil as an alternative edible oil for human consumption (Chan & Ismail, 2009; Cheng et al., 2016; Mariod et al., 2010; Mohamed et al., 1995). Natural antioxidants in kenaf seed oil may offer protective benefits against cancer (Wing et al., 2016). Additionally, kenaf seeds have been consumed to aid in weight gain and bruise healing (Alexopoulou et al., 2013). The plant exhibits various medicinal properties, including analgesic, aperitif, aphrodisiac, anti-inflammatory, and antioxidant effects, particularly in its leaves and seeds. It has also been associated with benefits such as weight gain, anemia treatment, and fatigue reduction (Kobaisy et al., 2001; Khare, 2007; Kubmarawa et al., 2009; Alexopoulou et al., 2013). Given its abundance and promising nutritional attributes, exploring kenaf seed oil's potential as an edible oil could diversify agricultural applications and contribute to healthier dietary options (Coetzee et al., 2008).
Plant seeds have historically served as vital sources of oils for dietary, medicinal, and industrial purposes, often obtained as valuable by-products from industrial fruit processing. Efficient pre-extraction and extraction processes are crucial for recovering bioactive components from plant materials. Optimizing these processes can enhance the yield and quality of essential oils, maximizing their commercial value and expanding their applications across various sectors (Daud et al., 2022). This research proposal outlines a systematic plan to observe and evaluate the nutritional composition and assess the edible application of kenaf seed oil.
II. Materials and Methods
Study location
The experiment was conducted in the laboratory of the Department of Breeder Seed, Bangladesh Jute Research Institute, Dhaka; Centre for Advanced Research in Sciences (CARS), University of Dhaka and WAFFEN Research Laboratory Limited from February 2024 to May 2024.
Materials used
Kenaf (Hibiscus cannabinus L.) variety HC-95 was released in 1995 (Figure 01) and collected from Jute Research Regional Station, Rangpur.
Step-1 Collection of Kenaf seed
Step-2 Extraction of kenaf seed oil
Step-3 Analysis of extracted kenaf seed oil
Figure 01. Kenaf seed sample Figure 02. Flowchart diagram of experimental design
Design of experiment
There were three steps followed for this experiment. The flow chart diagram is shown in Figure 02.
Procedures of extraction
Kenaf seeds have high oil content and are extracted through several methods. For this experiment, use solvent extraction method.
Seed weighting: Accurate measurement of the seed weight ensures consistency in the extraction process. In this case, 200 grams of seeds were chosen for extraction, but the quantity can vary based on the desired yield (Figure 03).
Drying: Drying the seeds helps to remove any moisture present, which could interfere with the extraction process. Typically, seeds were dried using air or oven drying methods until they reached a specified moisture content (Figure 04).
Figure 03. Measuring seed weights Figure 04. Drying Figure 05. Powder of kenaf seed
Grinding: The dried seeds were ground into a fine powder using a mechanical grinder or mill. Grinding increases the surface area of the seeds, enhancing the extraction efficiency by allowing better contact between the solvent and the seed material (Figure 05).
Mixing with solvent: Half of the ground powder (100 gm) was mixed with a solvent mixture containing 200 ml of hexane and 100 ml of water. Hexane was a common solvent used for extracting oils from seeds due to its ability to dissolve non-polar compounds like oils. The addition of water helps separate impurities and polar components from oil (Figure 06).
Extraction with Hexane
The prepared seed powder was conveyed to an extractor. In the extractor, the seed powder was exposed to hexane solvent. Hexane was chosen as a solvent because it selectively dissolves the oil present in the seeds. The seed powder was mixed with 200 ml hexane and 100 ml water.
Figure 6. Hexane mixed with powder
Figure 07. Hexane mixed with powder (Resting period)
Figure 08. Separating hexane from the mixture Figure
09. Hexane Evaporation
Resting period: After mixing, the mixture was allowed to rest for 2 hours. During this time, the hexane dissolved the oil present in the seeds, forming a mixture called miscella (Figure. 07).
Separation of miscella: After the resting period, the mixture of hexane and oil (miscella) was obtained. The liquid part (miscella) was separated from the solid residue (seed powder) using a pipette or other suitable means. The miscella, containing the dissolved oil, was collected for further processing (Figure 08).
Hexane Evaporation: The hexane-oil mixture obtained from the separation step was transferred to a suitable container, such as a beaker. The hexane was allowed to evaporate from the mixture, leaving behind the oil in the beaker. Evaporation could be facilitated by applying gentle heat or allowing the mixture to sit room temperature, depending on the volatility of hexane (Figure 09).
Oil collection from mixture
Once the hexane had completely evaporated, the oil residue left in the beaker was collected. The oil collected was the desired product of the extraction process and could be further processed or used as needed. This process ensures that the oil was efficiently extracted from the seeds using hexane as a solvent and then separated from the solvent for final collection.
Parameters tested for edible application
Determination of fatty acid composition ,
Fatty acid methyl ester (FAMEs) preparation: The fatty acid composition was determined by the conversion of oil to fatty acid methyl esters prepared by adding 30mg of oil followed by 3ml of Methanolic KOH (0.5N) and 2ml of Boron trifluoride methanol complex according to the method of AOAC 969.33 & 969.22 with some modifications. The mixtures were cooled, then 20ml saturated Sodium chloride solution was added and 15 minutes for settling. The upper phase containing the FAMEs was recovered by adding 8 ml of n-hexane and analyzed by Gas chromatography (GC- FID). 1 µl samples were injected into the Gas Chromatograph following standard conditions.
The percentage of fatty acid was calculated based on the peak area ratios of fatty acid species to the total peak area of all the fatty acids in the oil sample. The results were expressed in percentages (%). Fatty Acids are calculated individually by the following formula:
Individual Fatty acids %
=(Aera of sample component ×Concentration of standard component ×100)/(Aera of standard component)
Determination of specific gravity
The specific gravity content was determined according to the AOAC method , (AOAC 920.212). The sample was filter through a filter paper to remove any impurities and the last traces of moisture. Make sure that the sample is completely dry. Cool the sample to 30°C or ambient temperature desired for determination. The dry pycnometer was filled with the prepared sample in such a manner to prevent entrapment of air bubbles after removing the cap of the side arm. The stopper was inserted. The pycnometer was immersed in water bath at 30±2.0°C and held for 30 min. Carefully wiped off any oil that had come out of the capillary opening was carefully wiped off. The bottle was removed from the bath, cleaned and dried thoroughly. The cap of the side arm was removed and quickly weighed ensuring that the temperature did not fall below 30°C. Calculations were done with the following equation:
Specific Gravity at 30°C (g/ml)=(A-B)/(C-B)
Where,
A = weight in g of specific gravity bottle with oil at 30°C
B = weight in g of specific gravity bottle at 30°C
C = weight in g of specific gravity bottle with water at 30°C
Determination of Vitamin-E Test
Chromatographic condition:
Column: RP-C18 (Acclaim TM 120, 5µm, 150 × 4.6 mm)
Mobile phase: Methanol (100%)
UV detection: 292 nm
Injection volume: 20 μl
Flow rate: 1.0 ml/min
Run time: 10 mins
Sample Preparation
Accurately 0.5 g of oil sample was weighed in a brown 250 ml round bottom flask. 1 g of L-ascorbic acid was added. 50 ml of Ethanol (Absolute) was added, then 15 ml of 50% KOH was added. Saponification was performed using reflux condenser. Successful saponification was indicated by the disappearance of fatty drops. The sample was rinsed from a flask with 50 ml Ethanol and transferred into a 250 ml separating funnel. 120 ml water was added (breaking emulsion), then extraction was made with a total of 150 ml n-hexane. Hexane phase was washed with water until the KOH was cleared out from the hexane extract and the washings were drained off. Hexane phase was rotary evaporated at 50 °C at 260 mbar. The residue was dissolved in 10 ml of Methanol (HPLC Grade) and injected 20µl into the HPLC system.
III. Results and Discussion
Determination of fatty acid composition
A total of 21 fatty acids were analyzed, with 9 being detected and quantified (Table 01). The most abundant fatty acid was linoleic acid (C18:2), which constituted 49.43% of the total fatty acid content surpassing the levels reported by others [Mohamed et al. (1995): 42.0% to 50.1%, Karim et al. (2021): 29.97% to 31.21%, Ryu et. al. (2013): 36.35% to 39.35%)]. However linolenic acid content of 0.47%, which is consistent with the findings of Mohamed et al. (1995) and Ryu et. al. (2013), who reported ranges of 0.4% to 1.1% and 0.23% to 0.43% respectively for linolenic acid in KSO.
The level of myristic acid in the kenaf seed oil (KSO) sample was less than what was reported by Mohamed et al. (1995), who observed myristic acid levels ranging from 0.30% to 0.79%. Orsavova et al. (2015) noted 0.09% myristic acid in sunflower oil and 0.39% in rice bran oil. However, Frančáková et al. (2015) did not detect any myristic acid in sesame or olive oil.
The oil sample showed a palmitic acid level of 20.29%. This corresponds closely to the findings of Mohamed et al. (1995), who reported palmitic acid levels ranging from 18.6% to 21.4% in kenaf seed oil. However, Karim et al. (2021) and Ryu et. al. (2013) observed significantly higher levels of palmitic acid in kenaf seed oil, ranging from 26.49% to 26.93% and 32.77% to 34.97% respectively. The test KSO showed a palmitoleic acid content of 0.61%. Karim et al. (2021) also noted palmitoleic acid levels of 0.38% to 0.42% in KSO. However, Mohamed et al. (1995) reported a higher amount of palmitoleic acid in their study, ranging from 1.3% to 2.1%. Additionally, common vegetable oils contain lower amounts of palmitoleic acid, as indicated by Orsavova et al. (2015) (sunflower oil: 0.12%, sesame oil: 0.11%, rice bran oil: 0.19%).
The extracted KSO contained 0.06% heptadecanoic acid, a value closely resembling that reported by Karim et al. (2021) (0.04%). Likewise, Orsavova et al. (2015) stated that sunflower oil contains 0.02% heptadecanoic acid. The test sample contained 1.40% stearic acid. In comparison, Mohamed et al. (1995) reported stearic acid levels ranging from 2.0% to 4.0%, Karim et al. (2021) reported 2.70% to 3.64%, and Ryu et. al. (2013) noted 3.06% to 3.16% in their studies. However, other vegetable oils contain higher amounts of stearic acid, such as sunflower oil with 2.8% (Orsavova et al. 2015), and soybean oil with 4.07% (Chowdhury et al., 2007).
The tested KSO exhibited a 27.44% oleic acid content. This aligns with the findings of Mohamed et al. (1995) and Ryu et. al. (2013), who reported oleic acid levels ranging from 24.8% to 34.1% and 26.32% to 29.87%, respectively. However, Karim et al. (2021) observed higher oleic acid levels, ranging from 31.41% to 36.19% in KSO. Comparatively, other vegetable oils contain higher amounts of oleic acid, such as sunflower oil with 45.39% (Chowdhury et al., 2007), sesame oil with 40.75% (Frančáková et al., 2015). The tested KSO exhibited a lignoceric acid content of 0.14%, which is in line with the findings of Mohamed et al. (1995) (0.6% to 0.18%) and Karim et al. (2021) (0.09% to 0.11%). Similarly, sesame oil reported 0.09% lignoceric acid (Frančáková et al., 2015).
The analysis did not detect the presence of several fatty acids, including C6:0, C8:0, C10:0, C12:0, C17:1, C20:0, C20:1, C20:2, C22:0, C22:1, C22:2, and C24:1, indicating that their concentrations, if present, were below the detection limits of the analytical method employed. These findings highlight the potential nutritional value of kenaf seed oil, particularly due to its high content of linoleic and oleic acids, which are essential fatty acids with significant health benefits.
The composition suggests potential health implications, as unsaturated fatty acids are generally healthier than saturated ones. The ratio of omega-6 to omega-3 fatty acids (linoleic acid to linolenic acid) is important for assessing nutritional quality, with an optimal ratio of around 4:1.
Table 01. Determination of fatty acid composition from kenaf seed extract.
Analysis of tocopherol and specific gravity
Specific gravity
The specific gravity of the sample at 30°C was measured at 0.9124 g/ml. Specific gravity is a measure of the density of a substance compared to the density of a reference substance (usually water). This parameter can provide insights into the purity, concentration, or composition of the sample. In this case, it indicates the density of the substance at a specific temperature, which can be useful for various applications, including quality control and formulation (Table 02).
Total tocopherol
Tocopherols are a group of vitamin E compounds with antioxidant properties. The total tocopherol content in the test sample of KSO oil was measured at 77.07 mg/100g using High-Performance Liquid Chromatography (HPLC) (Table 02). This exceeds the values reported by Chew et al. (2016) (62.25-67.33 mg/100g), Chew et al. (2017a) and Chew et al. (2017b) (51.3–64.1 mg/100g), and Nyam and Lau (2015) (38.8 mg/100g) for total tocopherol per 100 g of kenaf seed oil. In terms of total tocopherol content, sunflower oil contains 80.6-85.2 mg/100g (Gliszczyńska-Świgło et al., 2007)) and soybean oil contains 81.7-84.1 mg/100g (Gliszczyńska-Świgło et al., 2007). This parameter reflects the overall concentration of tocopherols present in the sample, which is crucial for assessing its antioxidant activity and potential health benefits.
Alpha Tocopherol
Among the tocopherol compounds, α-tocopherol content in the test sample of KSO was measured at 43 mg/100g (Table 02). This is notably higher compared to findings from previous studies. For instance, Chew et al. (2016) reported a range of 12.14-16.72 mg/100g, while Chew et al. (2017a) and Chew et al. (2017b) found a range of 12.2–21.9 mg/100g. Nyam and Lau (2015) found even lower levels at 6.4-7.2 mg/100g α-tocopherol in KSO. In contrast, Gliszczyńska-Świgło et al. (2007) observed higher amounts of α-tocopherol (56.4-58.6 mg/100 g) in sunflower oil. Alpha-tocopherol is the most biologically active form of vitamin E and is known for its antioxidant properties. Its concentration in the sample indicates the presence of this vital compound, which contributes significantly to the sample's antioxidant capacity and potential health effects.
Beta Tocopherol and
The test sample of KSO oil showed a β-tocopherol content of 31.23 mg/100g (Table 02). This contrasts sharply with the findings of Chew et al. (2017a) and Chew et al. (2017b) who reported a much lower range of 6.4-6.8 mg/100g of β-tocopherol in KSO. Rafalowski et al. (2008) noted higher levels, observing 18.5 mg of β-tocopherol per 100 g of sunflower oil and 18.7 mg per 100 g of soybean oil. Desai et al. (1988) found a range of 0.5-2.9 mg of β-tocopherol per 100 g of rice bran oil, with only trace amounts in olive oil.
Table 02. Analysis of specific gravity and total Tocophrol in kenaf seed oil
Gama Tocopherol
The γ-tocopherol content in the test sample of KSO oil was measured at 31.23 mg/100g (Table 02). This falls within the range reported by Nyam and Lau (2015), who found 26.4-31.6 mg of γ-tocopherol per 100g of kenaf seed oil. Other studies yielded varying results, such as Chew et al. (2017a) , Chew et al. (2017b) reporting 17.8–27.2 mg/100g and Chew et al. (2016) reporting 46.52-54.18 mg/100g of γ-tocopherol in KSO. Carpenter (1979) documented γ-tocopherol levels of 3.8-3.9 mg/100g in sunflower oil, 91.0-93.8 mg/100g in soybean oil, and 1.9-2.1 mg/100g in olive oil.
Delta-tocopherol
The δ-tocopherol content in the test sample of kenaf seed oil was measured at 2.84 mg/100g. While its concentration is lower than other tocopherol forms, it still contributes to the sample's antioxidant capacity. This finding aligns with the results of Chew et al. (2017a), Chew et al. (2017b) and Nyam and Lau (2015), who reported ranges of 1.3–2.5 mg/100g and 2.9-3.1 mg/100g of δ-tocopherol in kenaf seed oil, respectively. Gliszczyńska-Świgło et al., (2007) observed δ-tocopherol levels of 2.90-3.10 mg/110g in sunflower oil and 17.9-18.5 mg/100g in soybean oil. Delta-tocopherol, along with the other tocopherol forms, collectively enhances the sample's stability and shelf life by protecting it from oxidative damage (Table 02).
IV. Conclusion
Overall, the analysis provides comprehensive information about the specific gravity and tocopherol composition of the sample, which are essential for evaluating its quality, nutritional value, and potential health benefits. These results can guide further research, development, and application of the sample in various industries, including food, cosmetics, and pharmaceuticals.
Article Citations:
MLA
Hasan, M. M. “Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit”. Journal of Bioscience and Agriculture Research, 33(01), (2024): 2675-2683.
APA
Hasan, M. M., Jahan, I., Abdullah, M. R., Karim, M. R., Hasan, M. M., Nesha, M. Z. and Banna, K. T. A. (2024). Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit. Journal of Bioscience and Agriculture Research, 33(01), 2675-2683.
Chicago
Hasan, M. M., Jahan, I., Abdullah, M. R., Karim, M. R., Hasan, M. M., Nesha, M. Z. and Banna, K. T. A. “Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit”. Journal of Bioscience and Agriculture Research, 33(01), (2024): 2675-2683.
Harvard
Hasan, M. M., Jahan, I., Abdullah, M. R., Karim, M. R., Hasan, M. M., Nesha, M. Z. and Banna, K. T. A. 2024. Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit. Journal of Bioscience and Agriculture Research, 33(01), pp. 2675-2683.
Vancouver
Hasan, MM, Jahan, I, Abdullah, MR, Karim, MR, Hasan, MM, Nesha, MZ and Banna, KTA. Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit. Journal of Bioscience and Agriculture Research, 2024 May, 33(01): 2675-2683.
Hasan, M. M. “Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit”. Journal of Bioscience and Agriculture Research, 33(01), (2024): 2675-2683.
APA
Hasan, M. M., Jahan, I., Abdullah, M. R., Karim, M. R., Hasan, M. M., Nesha, M. Z. and Banna, K. T. A. (2024). Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit. Journal of Bioscience and Agriculture Research, 33(01), 2675-2683.
Chicago
Hasan, M. M., Jahan, I., Abdullah, M. R., Karim, M. R., Hasan, M. M., Nesha, M. Z. and Banna, K. T. A. “Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit”. Journal of Bioscience and Agriculture Research, 33(01), (2024): 2675-2683.
Harvard
Hasan, M. M., Jahan, I., Abdullah, M. R., Karim, M. R., Hasan, M. M., Nesha, M. Z. and Banna, K. T. A. 2024. Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit. Journal of Bioscience and Agriculture Research, 33(01), pp. 2675-2683.
Vancouver
Hasan, MM, Jahan, I, Abdullah, MR, Karim, MR, Hasan, MM, Nesha, MZ and Banna, KTA. Exploring Kenaf (Hibiscus cannabinus L.) seed oil: Potential edible application and nutritional benefit. Journal of Bioscience and Agriculture Research, 2024 May, 33(01): 2675-2683.
References:
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[5]. Cheng, W. Y., Akanda, J. M. H. and Nyam, K. L. (2016). Kenaf seed oil: A potential new source of edible oil. Trends in Food Science & Technology, 1(52), 57-65. https://doi.org/10.1016/j.tifs.2016.03.014
[6]. Chew, S. C., Tan, C. P. and Nyam, K. L. (2017a). Application of response surface methodology for optimizing the deodorization parameters in chemical refining of kenaf seed oil. Separation and Purification Technology, 184, 144–151. ttps://doi.org/10.1016/j.seppur.2017.04.044
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[13]. Frančáková, H., Ivanišová, E., Dráb, S., Krajčovič, T., Tokár, M., Mareček, J. and Musilová, J. (2015). Composition of fatty acids in selected vegetable oils. Potravinarstvo Slovak Journal of Food Sciences, 9(1), 538-542. https://doi.org/10.5219/556
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[19]. Kubmarawa, D., Andenyang, I. F. H. and Magomya, A. M. (2009). Proximate composition and amino acid profile of two non-conventional leafy vegetables (Hibiscus cannabinus and Haematostaphis barteri). African Journal of Food Science, 3, 233–236.
[20]. Mariod, A. A., Fathy, S. F. and Ismail, M. (2010). Preparation and characterisation of protein concentrates from defatted kenaf seed. Food Chemistry, 123(3), 747–752. https://doi.org/10.1016/j.foodchem.2010.05.045
[21]. Mohamed, A., Bhardwaj, H., Hamama, A. and Webber, C. (1995). Chemical composition of kenaf (Hibiscus cannabinus L.) seed oil. Industrial Crops and Products, 4, 157–165. https://doi.org/10.1016/0926-6690(95)00027-A.
[22]. Mostafa, M. G., Rahaman, L. and Ghosh, R. K. (2013). Genetic analysis of some important seed yield related traits in kenaf (Hibiscus cannabinus). Journal of Natural Sciences, 47, 155–165.
[23]. Nyam, K. L. and Lau, H. W. (2015). Effects of microwave pre-treatment on the quality of kenaf (Hibiscus cannabinus L.) seed oil. Journal of Food Science and Engineering, 5, 14-21. https://doi.org/10.17265/2159-5828/2015.01.002
[24]. Orsavova, J., Misurcova, L., Ambrozova, J. V., Vicha, R. and Mlcek, J. (2015). Fatty acids composition of vegetable oils and its contribution to dietary energy intake and dependence of cardiovascular mortality on dietary intake of fatty acids. International Journal Molecular Science, 16(6), 12871-12890. https://doi.org/10.3390/ijms160612871
[25]. Rafalowski, R., Zegarska, Z., Kuncerncz, A. and Borgszo, Z. (2008). Fatty acid composition, tocopherols and ß-carotene content in Polish commercial vegetable oils. Pakistan Journal of Nutrition, 7(2), 278-282. https://doi.org/10.3923/pjn.2008.278.282
[26]. Ryu, J., Ha, B. K., Kim, D. S., Kim, J. B., Kim, S. H. and Kang, S. Y. (2013). Assessment of growth and seed oil composition of kenaf (Hibiscus cannabinus L.) germplasm. Journal of Crop Science and Biotechnology, 16(4), 297–302. https://doi.org/10.1007/s12892-013-0074-x
[27]. Ryu, J., Kwon, S. J., Ahn, J. W., Jo, Y. D., Kim, S. H., Jeong, S. W. and Kang, S. Y. (2017). Phytochemicals and antioxidant activity in the kenaf plant (Hibiscus cannabinus L.). Journal of Plant Biotechnology, 44(2), 191–202. https://doi.org/10.5010/JPB.2017.44.2
[28]. Wing, C. Y., Akanda, J. M. H. and Nyam, K. L. (2016). Kenaf seed oil: A potential new source of edible oil. Trends in Food Science & Technology, 52, pp.57-65. https://doi.org/10.1016/j.tifs.2016.03.014
[29]. Zawawi, N., Gangadharan, P., Zaini, R., Samsudin, M. G., Karim, R. and Ismail, M. (2014). Nutritional values and cooking quality of defatted Kenaf seeds yellow (DKSY) noodles. International Food Research Journal, 21, 603-608.
[2]. Alexopoulou, E., Papatheohari, Y., Myrsini, C. and Monti, A. (2013). Origin, Description, Importance, and Cultivation Area of Kenaf. Green Energy and Technology, 117, 1-15. https://doi.org/10.1007/978-1-4471-5067-1_1
[3]. Carpenter, A. P. (1979). Determination of tocopherols in vegetable oils. Journal of the American Oil Chemists’ Society, 56(7), 668–671. https://doi.org/10.1007/BF02660070
[4]. Chan, K. W. and Ismail, M. (2009). Supercritical carbon dioxide fluid extraction of Hibiscus cannabinus L. seed oil: A potential solvent-free and high antioxidative edible oil. Food Chemistry, 114(3), 970–975. https://doi.org/10.1016/j.foodche
[5]. Cheng, W. Y., Akanda, J. M. H. and Nyam, K. L. (2016). Kenaf seed oil: A potential new source of edible oil. Trends in Food Science & Technology, 1(52), 57-65. https://doi.org/10.1016/j.tifs.2016.03.014
[6]. Chew, S. C., Tan, C. P. and Nyam, K. L. (2017a). Application of response surface methodology for optimizing the deodorization parameters in chemical refining of kenaf seed oil. Separation and Purification Technology, 184, 144–151. ttps://doi.org/10.1016/j.seppur.2017.04.044
[7]. Chew, S. C., Tan, C. P., Lai, O. M. and Nyam, K. L. (2017b). Changes in 3-MCPD esters, glycidyl esters, bioactive compounds and oxidation indexes during kenaf seed oil refining. Food Science and Biotechnology. https://doi.org/10.1007/s10068-017-0295-8. (In press).
[8]. Chew, S. C., Tan, C. P., Long, K. and Nyam, K. L. (2016). Effect of chemical refining on the quality of kenaf (Hibiscus cannabinus) seed oil. Industrial Crops and Products, 89, 59–65. https://doi.org/10.1016/j.indcrop.2016.05.002
[9]. Chowdhury, K., Banu, L. A., Khan, S. and Latif, A. (2007). Studies on the fatty acid composition of edible oil. Bangladesh Journal of Scientific and Industrial Research, 42(3), 311-316. https://doi.org/10.3329/bjsir.v42i3.669
[10]. Coetzee, R., Labuschagne, M. T. and Hugo, A. (2008). Fatty acid and oil variation in seed from kenaf (Hibiscus cannabinus L.). Industrial Crops and Products, 27(1), 104–109. https://doi.org/10.1016/j.indcrop.2007.08.005
[11]. Daud, N. M., Putra, N. R., Jamaludin, R., Norodin, N. S. M., Sarkawi, N. S., Hamzah, M. H. S. and Salleh, L. M. (2022). Valorisation of plant seed as natural bioactive compounds by various extraction methods: A review. Trends in Food Science & Technology, 119, 201-214. https://doi.org/10.1016/j.tifs.2021.12.010
[12]. Desai, I. D., Bhagavan, H., Salkeld, R. and Dutra de Oliveira, J. E. (1988). Vitamin E content of crude and refined vegetable oils in Southern Brazil. Journal of Food Composition and Analysis, 1(3), 231–238. https://doi.org/10.1016/0889-1575(88)90004-X
[13]. Frančáková, H., Ivanišová, E., Dráb, S., Krajčovič, T., Tokár, M., Mareček, J. and Musilová, J. (2015). Composition of fatty acids in selected vegetable oils. Potravinarstvo Slovak Journal of Food Sciences, 9(1), 538-542. https://doi.org/10.5219/556
[14]. Gliszczyńska-Świgło, A., Sikorska, E., Khmelinskii, I. and Sikorski, M. (2007). Tocopherol content in edible plant oils. Polish Journal of Food and Nutrition Sciences, 57(4A), 157-161.
[15]. Hassan, K. M., Bhuyan, M. I., Islam, M. K., Hoque, M. F. and Monirul, M. (2018). Performance of some jute and allied fiber varieties in the southern part of Bangladesh. International Journal of Advanced Geosciences, 6(1), 117–121. https://doi.org/10.14419/ijag.v6i1.10184
[16]. Karim, R., Noh, N. A. M., Ibrahim, S. G., Ibadullah, W. Z. W., Zawawi, N. and Saari, N. (2021). Kenaf (Hibiscus cannabinus L.) seed extract as a new plant-based milk alternative and its potential food uses. Milk Substitutes - Selected Aspects. http://dx.doi.org/10.5772/intechopen.94067
[17]. Khare, C. P. (2007). Indian medicinal plants: An illustrated dictionary (pp. 309). London: Springer Verlag. https://doi.org/10.1007/978-0-387-70638-2
[18]. Kobaisy, Mozaina, Tellez, Mario, Webber, Charles, Dayan, Franck, Schrader, Kevin, Wedge and David (2001). Phytotoxic and Fungitoxic Activities of the Essential Oil of Kenaf (Hibiscus cannabinus L.) Leaves and Its Composition. Journal of agricultural and food chemistry, 49. 3768-71. https://doi.org/10.1021/jf0101455
[19]. Kubmarawa, D., Andenyang, I. F. H. and Magomya, A. M. (2009). Proximate composition and amino acid profile of two non-conventional leafy vegetables (Hibiscus cannabinus and Haematostaphis barteri). African Journal of Food Science, 3, 233–236.
[20]. Mariod, A. A., Fathy, S. F. and Ismail, M. (2010). Preparation and characterisation of protein concentrates from defatted kenaf seed. Food Chemistry, 123(3), 747–752. https://doi.org/10.1016/j.foodchem.2010.05.045
[21]. Mohamed, A., Bhardwaj, H., Hamama, A. and Webber, C. (1995). Chemical composition of kenaf (Hibiscus cannabinus L.) seed oil. Industrial Crops and Products, 4, 157–165. https://doi.org/10.1016/0926-6690(95)00027-A.
[22]. Mostafa, M. G., Rahaman, L. and Ghosh, R. K. (2013). Genetic analysis of some important seed yield related traits in kenaf (Hibiscus cannabinus). Journal of Natural Sciences, 47, 155–165.
[23]. Nyam, K. L. and Lau, H. W. (2015). Effects of microwave pre-treatment on the quality of kenaf (Hibiscus cannabinus L.) seed oil. Journal of Food Science and Engineering, 5, 14-21. https://doi.org/10.17265/2159-5828/2015.01.002
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