Physical and Chemical Characterization of Three Non-Toxic Oilseeds from the Jatropha Genus
1Centro de Investigación en Alimentación y Desarrollo, A. C. Coordinación, Culiacán, Sinaloa, México
2National Bioproducts and Bioprocesses Program, Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Summerland, BC, Canada
3CENTRO DE INVESTIGACIONES BIOLÓGICAS DEL NOROESTE, S.C, InstitutoPolitécnico Nacional 195, Playa Palo de Santa Rita Sur; La Paz, B.C.S., México
Jatropha is a multipurpose genus rich in oil that can be used to manufacture fuel, candles, soap, cosmetic and drugs. Defatted kernel meal of Jatropha non-toxic species can also be used as animal feed because of its protein high content. Three Jatropha species, J. cinerea, J. curcas and J. platyphylla grown in Northwest of México were evaluated for seed, oil and defatted meal characteristics. Seed characteristics, oil yield and fatty acid composition differed significantly among the genus with minimal variation in thermal oil characteristics. Jatropha oil yield (55-62%) was higher than other commercial oilseeds as soya and rapeseed. J. cinerea and J. platyphylla oils and their defatted meals exhibited similar characteristics and profiles. The levels of all essential amino acids, except lysine, were higher than the recommended for a child of 2-5 years old. Amino acid composition of J. curcas was superior to those of J. cinerea and J. platyphylla and can therefore be a potential alternative as an animal/human food for soybean meal.
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Keywords: Jatropha, curcas, cinerea, platyphylla, seed, oil, fatty acid, amino acid, thermal oxidation
Journal of Food and Nutrition Research, 2014 2 (1),
Received December 12, 2013; Revised January 15, 2014; Accepted February 16, 2014Copyright: © 2014 Science and Education Publishing. All Rights Reserved.
Cite this article:
- Sosa-Segura, María P., et al. "Physical and Chemical Characterization of Three Non-Toxic Oilseeds from the Jatropha Genus." Journal of Food and Nutrition Research 2.1 (2014): 56-61.
- Sosa-Segura, M. P. , Oomah, B. D. , C.G.Drover, J. , Heredia, J. B. , Osuna-Enciso, T. , Valdez-Torres, J. B. , Salazar-Villa, E. , Soto-Landeros, F. , & Angulo-Escalante, M. A. (2014). Physical and Chemical Characterization of Three Non-Toxic Oilseeds from the Jatropha Genus. Journal of Food and Nutrition Research, 2(1), 56-61.
- Sosa-Segura, María P., B. Dave Oomah, John C.G.Drover, José B. Heredia, Tomás Osuna-Enciso, José B. Valdez-Torres, Edith Salazar-Villa, Federico Soto-Landeros, and Miguel A. Angulo-Escalante. "Physical and Chemical Characterization of Three Non-Toxic Oilseeds from the Jatropha Genus." Journal of Food and Nutrition Research 2, no. 1 (2014): 56-61.
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Jatropha is a multipurpose genus rich in oil that can be used to manufacture fuel, candles, soap, cosmetic and drugs [4, 10]. The seed oils are potential renewable source for biodiesel production and the chemical industry. Currently, the most common feedstocks for biodiesel production are edible oils that according to many organizations are competing for resources with the food industry [9, 15].
The genus Jatropha derived from Greek iatros (Doctor) and trophe (food) belongs to the Euphorbiaceae family characteristic for its toxicity. The genus consists of over 170 species including Jatropha cinerea, J. curcas, and J. platyphylla native of Mexico and Centroamerica. A variety non-toxic J. curcas has been found only in Mexico . The roasted seeds of J. curcas and J. platyphylla are consumed by the local population for the preparation of traditional dishes [13, 14]. Defatted kernel meal of Jatropha non-toxic species can also be used as animal feed because of its protein high content.
This communication is the first scientific report for J. cinerea that has been found to have similar chemical characteristics to J. curcas that is widely promoted as a source of biofuel. J. cinerea is a drought resistant shrub 1-3 m high distributed from Arizona to Sinaloa coast in Mexico. Hearth-shaped leaves are 5 cm diameter with palmate venation. Seeds are small, brown shell and pearl white kernel. J. platyphylla is a drought-resistant perennial tree 2-5 m high from Sinaloa to Michoacán, México. J. curcas is a drought-resistant perennial shrub or tree widely distributed in tropical and subtropical areas. Its nutrient and water requirement is low, therefore is highly adaptable in marginal soils. It has received a lot of attention as a vegetable oil source for biodiesel production due to its agronomics advantages and oil characteristics; however, these parameters vary with genotype and environmental conditions [9, 10]. It has been reported 50-60% oil in kernel of J. curcas from Morelos, Veracruz and Puebla (México), consisting mainly of oleic (41.5-48.8%), linoleic (34.6-44.4%), palmitic (10.5-13%), and stearic acid (2.3-2.8%) . While, J. platyphylla native from Sinaloa contain 60% kernel oil, rich in oleic (23%) and linoleic acids (54%) .
Some factors on biodiesel quality are determined largely based on the fatty acid profile of oil. The cetane number value, cold-flow and cloud-point, viscosity, density and oxidative stability of biodiesel are directly related to the concentration of saturated fatty acid methyl esters (FAME’S) . The fatty acid profiles of J. curcas and platyphylla indicate that their oils have potential for the food and fuel industries . However, J. cinerea oil has not been evaluated and almost all reports are focused for the biodiesel production. This communication describes important physical characteristic of J. curcas, J. platyphylla and J. cinerea oil from Mexico. This is a continuation of our studies on complete utilization of horticultural crops for innovative uses and for the development of new products for the functional food, cosmetic, therapeutic and nutraceutical industries.
2. Materials and Methods
Fruits of the three Jatropha species, curcas, cinerea and platyphylla were collected in September 2011 in Sinaloa, Mexico. J. curcas fruits were obtained from pre-selected germplasms in our previous study in April, 2010  cultivated actually in an experimental field in Guasave, while J. cinerea fruits were picked from wild (native) trees in El Tambor, Culiacán, and J. platyphylla fruits were obtained from La Chilla, Culiacán and El Quelite, Mazatlán. The seeds were manually removed from the pulp, washed and allowed to dry. The seeds were transported to the Pacific Agri-Food Research Centre in Summerland (BC, Canada) and cracked open with pincers and the “kernels” stored in a desiccator prior to sample preparation. Twenty five kernels were taken randomly from each species. The length and diameter were measured with a Digimatic Caliper (Mitutoyo Canada Inc., Mississauga, ON, Canada) and expressed in mm. The weight was determined using an analytical balance, with an accuracy of ± 0.2 mg. Sphericity was calculated on the basis of length (a) and width (b) as sphericity % = [(b/a)1/2] x 100.
Kernel samples (34 ± 4 g) were cryomilled in a 6800 SPEX Freezer/Mill (SPEX, Metuchen, NJ 08840, USA) with a 1 min pre-cooling period and a two cycle program consisting of a 1.5 min grinding time, followed by 1 min cooling between grindings, and impactor speed of 14 s-1.
Oil from all milled samples was extracted using hexane . Briefly, the cryomilled sample (18 g) was stirred for 2 h at 4°C with hexane (75 mL). The solvent was removed by vacuum filtration and the sample was further extracted twice (2 h + 1 h). After the last filtration, the extracts were pooled, hexane removed (vacuum rotary evaporation, 30°C), purged with nitrogen and stored at -30°C until analysis. Extractions were performed in triplicate for the samples and analysed separately.2.1. Analytical Procedures
Spectroscopic indices, K232 and K270, in the UV region, were determined as outlined in the Standard Methods for the Analysis of Oils, Fats and Derivatives (International Union of Pure and Applied Chemistry, IUPAC, 1985). Absorbancies of a 10% (w/v) solution of oil in hexane was measured with a Spectrophotometer (SPECTRAmax Plus 384, Molecular Devices Corp., Sunnyvale, CA). Refractive index was measured with an Abbe Mark II refractometer. Density was calculated based on the weight and volume in a 2 mL oil aliquot.
FT-IR spectra of oils were recorded at 22°C using a Nicolet 380 spectrometer (Thermo Electron Corp., Madison, WI) with SMART iTR diamond attenuated total reflectance (ATR accessory) with a 45° aperture angle generating 1 bounce. The FT-IR was equipped with a deuterated triglycine sulfate (DTGS) detector scanning over the frequency range of 4000 to 400/cm at a resolution of 4/cm. Spectra were collected using a rapid scan software running under EZOMNIC 8.0.342 (Nicolet, Madison, WI) and the spectrum for each sample was calculated from the average of 32 repetitive scans. A single drop of oil was placed directly onto the ATR crystal and compressed using a standard pressure tower equipped with a pointed flat tip before spectra collection. Spectra were collected in triplicate for each extract.
Thermal characteristics of oils were measured using a modulated differential scanning calorimeter (Modulated DSC-2910, TA Instruments, New Castle, DE). A flow of nitrogen gas (145 mL/min) was used in the cell cooled by helium (145 mL/min) in a refrigerated cooling system. The instrument was calibrated for temperature and heat flow with mercury (melting point, mp = -38.83°C, TA Instruments standard), succinonitrile (mp = 58.06°C, Fluka Chemie AG) and indium (mp = 156.6°C, ΔH = 28.71 J/g, Aldrich Chemical Co.). Oil samples (4-5 mg) were weighed in open solid fat index (SFI) aluminium pans (T70529, TA Instruments). An empty similar pan was used as reference. The sample and reference pans were then placed inside the calorimeter and kept at 70°C for 5 min. The temperature was lowered from 70 to -65°C at a rate of 1°C/min with modulation at a period of 60 s and temperature amplitude of 0.16°C. Samples were then kept at -65°C for 1 min, and then raised again at the same rate up to 70°C. Scans were performed at 1°C/min. For thermal oxidation, pans were cooled to 10°C and scanning was done by heating at 10°C/min to 350°C in the presence of oxygen (100 mL/min). Thermal oxidation measurements were performed in triplicate.
The lipids were esterified in an alkaline medium (methanolic 1 M KOH) essentially as described previously . Oil (30 mg) was weighed into screw capped vials and, sequentially, 1 mL each of tetrahydrofuran, methanolic 1 M KOH, and 2 mL tridecanoic acid (0.483 mg/mL, in isooctane) were added. The mixture was vortexed briefly and after 1 min of standing, 1 mL of boron trifluoride (14% in methanol, Pierce Chemical, Rockford, IL) was added and mixed thoroughly. The solution was heated for 15 min at 100°C and then cooled, and 0.5 mL of saturated NaCl was added. After thorough mixing, the upper layer was used directly for gas chromatography (GC). Chromatography was performed using a Supelco SP-2560 fused silica capillary [100 m X 0.25 mm i.d., 0.20 µm film thickness (Supelco, Bellefonte, PA)] column in an Agilent 5890 GC (Agilent Technolgies Inc., Wilmington, DE) equipped with a flame ionization detector. Samples (1 µL) were injected using a model 7673 autoinjector and a split-splitless injector with a split ratio of 46:1. The oven program consisted of an initial temperature of 140°C for 5 min, followed by a temperature ramp to 240°C at 4°C/min. The temperature was held at 240°C for 30 min. Injector and detector temperatures were 260°C, and carrier gas (helium) was used in constant flow of 0.5 mL/min at 190kPa pressure. The instrument was controlled and data collected and quantitated with an Agilent ChemStation (version A.10.02). Analysis was done in triplicate. Peak identity was assessed based on the relative retention times of peaks compared to the tridecanoic acid internal standard versus those observed in a commercial mixture of 37 fatty acid methyl esters (Supelco, Bellefonte, PA).
Protein (N × 6.25) was determined by a nitrogen combustion method (FP-528, LECO Instruments Ltd., Mississauga, ON, Canada). The amino acid composition was determined by high performance liquid chromatography . At least three determinations were made for all assays. Analysis of variance by the general linear models (GLM) procedure and means comparisons by Duncan’s test were performed according to Statistical Analysis System .
3. Results and Discussion
Jatropha species differed significantly in kernel characteristics (Table 1). J. platyphylla kernels had twice the weight and the largest diameter than those of J. cinerea or J. curcas suggesting higher unit seed oil and protein. However, J. platyphylla kernel represented 50%, whereas those of J. curcas and J. cinerea accounted for only ≤ 35% of the total seed weight (data not shown). The seed weight of J. curcas was almost half of those reported for seeds grown in Mali . J. curcas had the longest kernel and the smallest diameter resulting in less spherical, almost elliptical shape than those of cinerea and platyphylla. The small cinerea seed has a thin shell that may be used together with the kernel to provide additional fiber thereby avoiding the cracking step in the process. J. platyphylla and J. curcas shell have gross energy 19.6 MJ/Kg  and can be used as energy pellets. The data in this study shows the necessity to search optimal methods to remove the kernel/shell in each species.
The oil yield differed significantly (p < 0.0001) among Jatropha species (Table 1) with J. curcas and J. cinerea producing the highest and lowest oil yield, respectively. The high yield/oil extraction (5% difference compared to J. cinerea) is a marketable benefit for both J. curcas and J. platyphylla. Jatropha oil yield (55-62%) is higher than other commercial oilseeds as soya and rapeseed (20 and 40%, respectively). Extraction efficiency or oil yield from J. curcas were higher than those grown in Indonesia  or from Mali . Our results are in accordance with previous report of J. curcas and J. platyphylla [12, 13]. Oil refractive index (1.471) and density (0.905-0.914) were not significantly different among the samples but similar to edible vegetable oils .
Jatropha oils had two main absorbance peaks in the UV-C region (272 and 282 nm; 10% oil in hexane). The absorbances at 272 nm were 0.84 ± 0.02, 1.24 ± 0.01, and 1.72 ± 0.04 for J. curcas, J. cinerea and J. platyphylla, respectively (Figure 1). The second peak (282 nm) followed absorption trend similar to that at 272 nm with 0.90 ± 0.02, 1.26 ± 0.01, and 1.61 ± 0.04 for J. curcas, J. cinerea and J. platyphylla, respectively. The high absorption of J. platyphylla oil suggests cis configurations and higher diene conjugations than those of J. cinerea and J. curcas. Mean absorptivity at 245 nm were 0.031, 0.034, and 0.036 for J. cinerea, J. curcas, and J. platyphylla oils respectively, inferring presence of yellow pigment in the oils (data no shown).
Jatropha oils revealed similar structures in the IR spectrum (Figure 2). The spectrum showed typical absorption bands assigned to the vibrations in the long carbonyl chain (3005), aliphatic alkyl chain (2923-2853), carbonyl groups in aldehydes and ketones (1740-1745), free fatty acid (1700-1720), bands associated with doubles bonds (1640-1680), methylene excited groups (1463), etheric bands (1230-1030) and ether linkages (1161-1099). Our FTIR data are similar to those reported for sophorolipids, a class of biosurfactants produced from Jatropha oil . Similar bands in six different seed oils and four almond cultivars, respectively, were identified. None of three species showed atypical absorbance bands.
Fatty acid profile (FAP) differed significantly (p < 0.0001) among the species (Table 2) and was similar to previous report of J. curcas and J. platyphylla oils [13, 19]. The most abundant fatty acids were the unsaturated linoleic (43-52%) and oleic (25-37%) acids, and the saturated palmitic (10-13%) and stearic (6-8%) acids. FAP were similar for the species, although concentration of individual fatty acids varied (Table 2). The higher level of palmitic acid led to an increase in total saturated fatty acids in J. platyphylla compared to oil of the other species. Similarly, the low level of oleic acid of J. platyphylla oil accounted for its low monounsaturated fatty acid content. This resulted in the higher polyunsaturate: saturate ratio of J. platyphylla oil relative to the other species. The ratio of saturated fatty acids to unsaturated fatty acids (S:U), a commonly used criteria to describe the nutritional value of fat, was also high for J. platyphylla (0.28) compared to 0.24 for the other species, indicating its potential as an alternative edible oil feed source. The content of linoleic acid from J. curcas was higher (43% vs 35%), whereas those of other fatty acids were lower than those grown in Mali .
This suggests that Jatropha grown in the northern hemisphere may be predisposed to higher unsaturated oil than those grown in the south. J. cinerea and J. curcas oils have fatty acid profile similar to those of sesame and canola oils, whereas J. platyphylla oil profile resembles those of soybean oil. The ratio of oleic to linoleic acid in J. platyphylla was 1:2 (25 and 52%, respectively), which reflects its greater potential as an edible oil than those of J. curcas and J. cinerea (1:1.2; 1:1.4, respectively) due to linoleic acid benefits for human health (Table 2). It has been  reported 50-60% oil in J. curcas seed from Morelos, Veracruz and Puebla (México), composed mainly of oleic (41.5-48.8%), linoleic (34.6-44.4%), palmitic (10.5-13%) and stearic (2.3-2.8%) acids. On other hand, was reported oleic (23%) and linoleic (54%) acids in J. platyphylla .
Jatropha seed oil exhibited at least five distinct thermal structural transitions between -57 and -5°C. Three reversing transitions (between -37 and -5°C), indicative of crystalline melting, were observed corresponding to α-and β-polymorphic forms (peaks 1 and 2), respectively. The reversing component of the heat ﬂow was highly complex and varied for the species with oils from J. platyphylla exhibiting overall lower transition temperature and higher heat flow for the first two transitions than those of J. cinerea and J. curcas (Table 3). Both the transition temperature and heat flow of the third reversing transition were highly variable for the oil species with J. platyphylla and J. curcas oils exhibiting the highest and lowest enthalpy, respectively. Similarly, the nonreversing temperature of J. platyphylla seed oil and crystallization enthalpy of J. curcas seed oil were higher than those of the other two species (Table 3).
The thermal analysis of the Jatropha oils exhibited two maximum exothermic peaks (Table 4, Figure 3) with oxidation starting at 162-170°C, within the range reported for edible oils (130-180°C). The significantly higher onset (p < 0.05) and oxidation temperatures (p < 0.0005) of cinerea oil indicated its higher instability due to the highest unsaturated fatty acid content compared to other species. Oxidation of J. cinerea oil occurred at lower (peak 1) and higher (peak 2) temperatures relative to oil from the other species, although peak temperatures were not significantly different among the species. The first oxidation occurred between 205-236°C and the final between 295-305°C with J. curcas and J. platyphylla oils exhibiting similar oxidation profiles (Figure 3). The second peak indicates the inability of oxygen uptake, resulting in the complete oxidation. This information is useful for identifying and selecting species that are more resistant to oxidative degradation, since high temperature processing may affect oil quality. We have identified high oxidative stability in Jatropha oils.
The protein content was high in the three species (62-71%). J. curcas, J. cinerea and J. platyphylla defatted kernel meal had 62.4, 67.6 and 70.5% protein content, respectively. Amino acid content of defatted J. curcas meal was generally higher than those of J. cinerea and J. platyphylla with similar amino acid profile (Table 5). The levels of all essential amino acids, except lysine, were higher than the recommended for a child of 2-5 years old (Table 3) . Jatropha proteins are high in the essential branched chain amino acids (BCAA) comparable to that of soybean (Table 5). The lysine/arginine ratio, a determinant of the cholesterolaemic and atherogenic effects of a protein, is low for Jatropha protein, suggesting that it is less lipidemic and atherogenic than soybean protein with a lysine/arginine ratio of 0.88. Jatropha protein is also an excellent source of arginine, glutamine and histidine, the three amino acids known to have strong effects on the immune function of the body, and the aromatic amino acids (AAA) phenylalanine, tyrosine and tryptophan essential for animals. J. curcas protein is rich in most amino acids, BCAA and AAA essential for animal nutrition and exceptionally high immune boosting amino acids surpassing those of soybean protein, the gold standard protein for animal feed. The protein content and amino acid composition of Jatropha species were higher than those of soybean meal and other reported oilseeds. The species evaluated in this study are non-toxic (non-detectable phorbol esters levels), could be used as edible oil or besides the manufacture of biodiesel. Bioassays are necessary to confirm physicochemical properties and guide their potential use.
This communication shows that J. cinerea (a species not previously studied) contain high oil and protein, such as J. curcas and J. platyphylla. This report reveals three oilseed species native to México with potential for oil and protein extraction. Jatropha oil in all three species showed similar characteristics to the oil of other species commonly used for the manufacture of edible oil, as well as for the production of biodiesel. The high protein content and amino acid composition exceeded those reported in soy, the main animal feedstock and in this regard J. curcas meal can be a potential alternative for soybean meal in animal as well as human sports nutrition.
This work was funded by CONACYT-FORDECYT, INAPI (Sinaloa), México and IICA, Canada. We thank Eduardo Sanchez-Valdez, Werner Rubio-Carrasco, Nidia Araiza, Alberto Ochoa-Felix and Marianne Meneley for their technical support to develop this project.
|||Aremu, M.O., Olaofe, O., Akintayo, E.T., Lajide, L., 2006. Characteristics of legume seed oils by Fourier Transform Infrared spectroscopy. Biosc. Biotech. Res. Asia 3, 1-4.|
|||Beltrán, S. A., Prats, M.M.S., Maestre, P.S.E., Grané, T.N., Martín, C.M.L., 2009. Classification of four almond cultivars using oil degradation parameters based on FTIR and GC data. J. Am. Oil Chem. Soc. 86, 51-58.|
|||Beveridge, T.H.J., Girard, B., Kopp, T., Drover, J.C.G., 2005. Yield and composition of grape seed oils extracted by supercritical carbon dioxide and petroleum ether: varietal effects. J. Agric. Food Chem. 53, 1799-1804.|
|||Brittaine, R., Lutaladio, N., 2010. Jatropha: a smallholder bioenergy crop. Food and Agriculture Organization of the United Nations, Roma. Integrated Crop Management. 8, 96p.|
|||CODEX STAN 210-1999. Codex standard for named vegetable oils. Adopted 1999. Revisions 2001, 2003, 2009. Amendment 2005, 2011.|
|||FAO. Protein quality evaluation; report of the joint FAO/WHO expert consultation. FAO Food and Nutrition (Paper 52); Food and Agriculture Organization of the United Nations (FAO): Rome, Italy, 1990.|
|||Freire, L.M.S., Bicudo T.C., Rosenhaim, R., Sinfronio F.S.M., Botelho J.R., Carvalho Filho, J.R., Santos I.M.G., Fernandes Jr, V.J., Antoniosi Filho N.R., Souza, A.G., 2009. Thermal investigation of oil and biodiesel from Jatropha curcas L. J. Therm. Anal. Calorim. 96, 1029-1033.|
|||Jongschaap, R.E.E., Corre, W.J., Bindraban, P.S., Brandenburg, W.A., 2007. Claims and Facts on Jatropha curcas L. Plant Res. Int. B.V. Report 158.|
|||King, A.J., He, W., Cuevas, A.J., Freudenberger, M., Ramiaramamama, D., Graham, I.A., 2009. Potential of Jatropha curcas as a source of renewable oil and animal feed. J. Exp. Bot. 60, 2897-2905.|
|||Kumar, A., Sharma, S., 2008. An evaluation of multipurpose oil seed crop for industrial uses (Jatropha curcas L.): A review. Ind. Crops Prod. 28, 1-10.|
|||Makkar, H.P.S., Becker, K., Schmook, B., 1998. Edible provenances of Jatropha curcas from Quintana Roo state of Mexico and effect of roasting on antinutrient and toxic factors in seeds. Plant Foods Human Nutr. 52, 31-36.|
|||Makkar, H.P.S., Becker, K., Sporer, F., Wink, M., 1997. Studies on nutritive potential and toxic constituent of different provenances of Jatropha curcas. J. Agric. Food Chem. 45, 3152-3157.|
|||Makkar, H.P.S., Kumar, V., Oyeleye, O.O., Akinleye, A.O., Angulo-Escalante, A., Becker, K., 2011. Jatropha platyphylla, a new non-toxic Jatropha species: Physical properties and chemical constituents including toxic and antinutritional factors of seeds. Food Chem. 125, 63-71.|
|||Martinez-Herrera, J., Siddhuraju, P., Francis, G., Dávila-Ortíz, G., Becker, K., 2006. Chemical composition, toxic/antimetabolic constituents, and effects of different treatments on their levels, in four provenances of Jatropha curcas L. from Mexico. Food Chem. 96, 80-89.|
|||Nithiyanantham, S., Siddhuraju, P., Francis, G., 2012. Potential of Jatropha curcas as a Biofuel, Animal Feed and Health Products. J. Am. Oil Chem. Soc. 89, 961-972.|
|||Oomah, B.D., Mazza, G., Przybylski, R., 1996. Comparison of flaxseed meal lipids extracted with different solvents. Lebensm,-Wissens. Technol. 29, 654-658.|
|||Rathbauer, J., Sonnleitner, A., Pirot, R., Zeller, R., Bacovsky, D., 2012. Characterisation of Jatropha curcas seeds and oil from Mali. Biomass Bioenergy. 47, 201-210.|
|||Singh, R.K., Padhi, S.K., 2009. Characterization of jatropha oil for the preparation of biodiesel. Nat. Prod. Radiance. 8, 127-132.|
|||Sosa-Segura, M.P., Angulo-Escalante, M.A., Valdez-Torres, J.B., Heredia, J.B., Osuna-Enciso T., Allende-Molar R., Dave Oomah B., 2012. Phenology, productivity, and chemical characterization of Jatropha curcas L. as tool for selecting non-toxic elite germplasm. Afr. J. of Biotechnol. 11, 15988-15993.|
|||SAS Institute, Inc., 1990. SAS/STAT User’s Guide, Version 6, 4th ed.; SAS Institute: Cary, NC.|
|||Tambunan, A.H., Situmorang, J.P., Silip, J.J., Joelianingsih, A., Araki, T., 2012. Yield and physicochemical properties of mechanically extracted crude Jatropha curcas L oil. Biomass Bioenergy. 43, 12-17.|
|||Vázquez-Ortiz, F., Caire, G., Higuera-Ciapara, I., Hernández, G., 1995. High performance liquid chromatographic determination of free amino acids in shrimp. J. Liq. Chrom. 18, 2059-2068.|
|||Wadekar, S.D., Kale, S.B., Lali, A.M., Bhowmick, D.N., Pratap, A.P., 2012. Jatropha oil and karanja oil as carbon sources for production of sophorolipids. Eur. J. Lipid Sci. Technol. 114, 823-832.|