Temperature-dependent diffusion coefficient of oil from different sunflower seeds during extraction with hexane

Extraction of canola seed (Brassica napus) oil using compressed propane and supercritical carbon dioxide

This study highlights the effect of solvent polarity on the yield (Y%) and properties of oil extracted from Algerian sesame seeds. Extractions were carried out under Soxhlet conditions with the following solvents: hexane (Hx), ethanol (Eth), acetone (Ac), dichloromethane (Di), isopropanol (Iso), hexane:isopropanol (Hx:Iso), and chloroform:methanol (Chf:Me). The sesame oil yield obtained using different solvents ranged from 28.86 to 52.83%. Fatty acids and sterols analyses were performed by GC on capillary column. γ-Tocopherol was the major tocochromanol compound detected by HPLC-fluorescence. Fourteen fatty acids were identified, with the predominance of oleic and linoleic acids. The main sterol in sesame oil was β-sitosterol, followed by stigmasterol, campesterol, and Δ5-avenasterol which were present in lower concentrations. High correlations were found between arachidic, gadoleic, behenic, and lignoceric acids concentrations; these results were explained by the metabolic biosynthesis pathway of the biologically active long-chain PUFA by successive elongation and desaturation. Principal component analysis (PCA) of the data obtained from sesame oil composition enabled an easy comparison of the different extraction solvents, and correlated their properties with the most characteristic components of the extracted oils with a view to understand solvent–oil interaction, and to establish the effects of extracting solvent on such oil composition.

Practical applications: This study showed that the choice of solvent depends largely on the desired fraction to be extracted. Sesame oil was better extracted with less-polar solvents but membrane-associated lipids are more polar and require polar solvents capable of breaking hydrogen bonds or electrostatic forces. Owing to the differences in solvent capacity, the fatty acids, sterols, and tocopherols extracted along with the oil vary, leading to differences in the quality of the extracted oil. The results obtained in this study could be applied in industrial extraction to encourage the use of alternative extraction solvents.

Effect of the extraction solvent polarity on the sesame seeds oil composition

Production and refining of oils and fats

The solvent extraction process of jojoba oil from the meal cake obtained after the mechanical pressing of jojoba seeds was studied. Commercial hexane and petroleum ether were used as solvents and the extraction was carried out at temperatures ranging from 30 to 55 °C using solvent-to-solid ratios, R between 2 and 15 L/kg. The equilibrium compositions of the solvent and solid phases were determined. Based on the equilibrium data, the partition coefficient or distribution ratio, D of the oil between both phases was estimated. Also, the number of extraction stages necessary to achieve a certain degree of oil recovery has been determined using different hexane-to-meal ratios. Jojoba oil was also tested for its physical and chemical properties including chemical composition, percentage fatty acid, peroxide value, flash point, fire point, pour point, refractive index, saponification and iodine values. The stability of jojoba oil during storage at room temperature and during heat treatment was also studied.

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Solvent extraction of jojoba oil from pre-pressed jojoba meal

The equilibrium relationships in the extraction process that was developed in our research laboratory for the treatment of canola were studied. In the process, hexane is used as well as CH3OH that contains 5% (vol/vol) H2O and 0.08% (w/w) NaOH to simultaneously produce improved meal and high-quality oil. Equilibrium data for canola oil in the hexane-CH3OH/H2o/NaOH, meal-hexane, and meal-CH3OH/H2O/NaOH-hexane systems are reported. A high partition coefficient for oil between hexane and the polar phase provided a large driving force for mass transfer. The presence of the CH3OH phase improved oil extraction, probably by rupturing the cell structure. The process proved to be a somewhat less desirable replacement for CH3OH/H2O/NH3 extraction and recovered 93.5% of the oil and 91.8% of the protein in the seed, while with CH3OH/H2O/NH3, the oil and protein recoveries were 96.8 and 94.0%, respectively. The NaOH treatment removed only 50.2% of the glucosinolates, and some of the oil was hydrolyzed by the NaOH, making the process less effective, despite its simplicity.

Two‐phase solvent extraction of canola

An extraction process was developed in our laboratory for rapeseed (canola) with 10% (w/w) ammonia in methanol, containing 5% (vol/vol) water, and hexane to simultaneously produce an improved meal and a high-quality oil. To remove the hazards associated with the use of ammonia, a two-phase solvent extraction, with 0.08% (w/w) sodium hydroxide replacing the ammonia, was tested on a semipilot scale with a Szego mill and a Karr reciprocating-plate extraction column. Flooding curves and appropriate agitation parameters were examined for this system. Then, the effects of polar solvent-to-seed ratio, slurry-to-hexane flow ratio, plate amplitude and plate agitation frequency on extraction efficiency were investigated. The process is technically viable for industrial application. A meal that contained 0.9% residual oil, 44.4% protein and 2.79 mmol/kg glucosinolates (moisture and oil-free basis) and a miscella with 19.5% oil were obtained.

Mahmood Thobani

Papers

Two‐phase solvent extraction of canola

Pilot-scale two-phase extraction of canola