Extraction of wheat germ oil by supercritical CO<Subscript>2</Subscript>: Oil and defatted cake characterization

In this paper the working conditions for the extraction of wheat germ oil in a supercritical CO₂ pilot plant of 1-L-extraction capacity were studied. The best conditions were: pressure, 38 MPa; temperature, 55°C; wheat germ particle size, about 0.35 mm; CO₂ flow rate, 1.5 L min⁻¹. These conditions gave yields of about 92% of total oil after 3 h of processing. The obtained oils and the partially defatted cake were investigated with regard to their FA, tocol (tocopherol and tocotrienol), carotenoid, and sterol compositions and to their quality characteristics (FFA, PV, para-anisidine value, and color of the by product). Moreover, the oil quality was evaluated in relation to the progress of the supercritical extraction.     

Influence of operation variables on quality parameters of olive husk oil extracted with CO<Subscript>2</Subscript>: Three-step sequential extraction

Supercritical CO₂ extraction is a viable alternative process for the extraction of high-quality oil from olive husk (also known as olive pomace), a residue obtained in the production of olive oil. We analyzed the effect of pressure (100–300 bar), temperature (40–60°C), solvent flow (1–1.5 L/min), and particle size (0.30–0.55 mm) on four important quality parameters of the oil extracted with CO₂: tocopherol concentration, extinction coefficients at 232 and 270 nm, and saponification value. Response surface methodology was used to obtain mathematical expressions related to the operating variables and parameters studied. Results from these experiments were also used to design a three-step sequential CO₂ extraction procedure to obtain a higher-quality extract. The optimal operational sequence consisted of a first extraction step at 75 bar for 1 h using 1% (vol/vol) ethanol modifier, followed by a second extraction stage at 350 bar for 2.5 h without ethanol and a third step, also at 350 bar, for 2.5 h but using ethanol. These extraction conditions obtained an intermediate fraction of oil with 64% yield and all normal parameters according to European Commission food legislation. This fraction is suitable without any further refining. On the contrary, the oils obtained by hexane extraction and by conventional supercritical CO₂ extraction at optimal conditions are suitable for human consumption after further refining. This last finding may result in improved economics of the sequential CO₂ extraction process compared to the conventional extraction method with hexane.     

Supercritical fluid extraction of jojoba oil

Supercritical fluid extraction of jojoba oil from Simmondsia chinensis seeds using CO₂ as the solvent is presented in this study. The effects of process parameters such as pressure and temperature of extraction, particle size of jojoba seeds, flow rate of CO₂, and concentration of entrainer (hexane) on the extraction yield were examined. Increases in the supercritical CO₂ flow rate, temperature, and pressure generally improved the performance. The extraction yield increased as the particle size decreased, indicating the importance of decreasing intraparticle diffusional resistance. The maximum extraction yield obtained was 50.6 wt% with a 0.23-mm particle size and a 2 mL/min CO₂ flow rate at 90°C and 600 bar. Use of an entrainer at a concentration of 5 vol% improved the yield to 52.2 wt% for the same particle size and also enabled the use of relatively lower pressure and temperature, i.e., 300 bar and 70°C.     

Extraction of oil and β-sitosterol from peach (Prunus persica) seeds using supercritical carbon dioxide

Oil was extracted from the peach (Prunus persica) seeds by supercritical carbon dioxide. Principal phytosterols (stigmasterol, campesterol and β-sitosterol) that have been known to have cholesterol lowering properties were investigated in the extracted oil. Based on gas chromatography–mass spectrometry (GC–MS) analysis, β-sitosterol was identified in the peach seed oil. The effects of temperature, pressure, flow rate of supercritical CO₂, mean particle size of the seeds and extraction time on the amounts of extracted oil and β-sitosterol were investigated. Supercritical fluid extractions were performed in a range of 35–55 °C, 160–240 bar, 4–8 ml CO₂/min, 0.3–1.7 mm and 1–4 h for mentioned parameters. The results indicated that the amounts of oil and β-sitosterol extracted from the peach seeds were optimal with values of 35.3 g/100 g seed and 1220 mg/kg seed respectively at 40 °C, 200 bar, 7 ml/min, 0.3 mm and 3 h.     

Extraction of peanut skin oil by modified supercritical carbon dioxide: Empirical modelling and optimization

ABSTRACT

Peanut skin is a waste by-product from peanut industries. It is rich in antioxidants and bioactive compounds. Therefore, the objective of this study was to empirically model and optimize supercritical CO₂ extraction of oil from peanut skin. The extraction conditions were pressure (100, 200 and 300 bar), temperature (313, 328 and 343 K) and rate of modifier ethanol (0.075, 0.15 and 0.225 mL/min). The extraction process was subsequently examined using modified Brunner and Esquivel models. The optimum conditions for extraction peanut skin oil were 279 bar, 70°C and rate of modifier of 7.5% with a maximum yield of peanut skin oil of 0.83 g and initial slope of 0.568 g/min.     

Comparison of Supercritical Fluid and Hexane Extraction Methods in Extracting Kenaf (<Emphasis Type="Italic">Hibiscus cannabinus</Emphasis>) Seed Oil Lipids

The objective of this study was to investigate and compare fatty acids, tocopherols and sterols of kenaf seed oil extracted by supercritical carbon dioxide and traditional solvent methods. Fatty acids, tocopherols and sterols were determined in the extracted oils as functions of the pressure (400 bar, 600 bar), temperature (40 °C, 80 °C) and CO₂ flow rate (25 g/min) using a 1-L extraction vessel. Gas chromatography was used to characterize fatty acids and sterols of the obtained oils while tocopherols were quantified by HPLC. No differences were found in the fatty acid compositions of the various oil extracts and the main components were found to be linoleic (38%), oleic (35%), palmitic (20%) and stearic acid (3%). Extraction of tocopherols using high pressure (600 bar/40 °C, 600 bar/80 °C) gave higher total tocopherols (88.20 and 85.57 mg/100 g oil, respectively) when compared with hexane extraction which gave yield of 62.38 mg/100 g oil. Extraction of kenaf seed oil using supercritical fluid extraction at high temperature (80 °C) gave higher amounts of sterols when compared with hexane extraction.     

Supercritical CO2 extraction of omega-3 rich oil from Sacha inchi (Plukenetia volubilis L.) seeds

Supercritical carbon dioxide (SC-CO₂) was employed to extract omega-3 rich oil from Sacha inchi (Plukenetia volubilis L.) seeds and partially defatted cake. For ground seeds, the supercritical extraction was carried out at temperatures of 40, 50 and 60 °C and pressures of 300 and 400 bar, and for the cold pressed partially defatted cake, the extraction was carried out with 300 bar at 40 °C and with 400 bar at 60 °C. The global extraction yields (X₀), oil solubility, fatty acid composition of the oil and tocopherol content were determined. The seed samples used in this work contained 54.3% oil, of which 50.5% was linoleinc acid (ω-3). The maximum extraction recovery for the seeds as 92% at 400 bar and 60 °C, but on one occasion a recovery of 99.1% oil was obtained when cold pressed extraction was employed, followed by supercritical extraction at 400 bar and 60 °C. A high tocopherol content of about 2–3 g/kg of oil was obtained.     

Modeling and optimization of process parameters for supercritical CO2 extraction of Argemone mexicana (L.) seed oil

This research article deals with the determination of optimal conditions of extraction parameters (e.g. temperature (60–100?°C), pressure (200–350?bar), particle size (0.5–1.0?mm), flow rate-CO₂ (5–15?g/min), and the % of co-solvent (0.0–10% of flow rate-CO₂) resulting to the optimal cumulative extraction yield during the supercritical fluid extraction of Argemone mexicana (L.) seed oil with and without a modifier (ethanol) using a supercritical carbon dioxide as solvent. A “five-factors-three-levels” Box-Behnken design under the response surface methodology was used to show independent and interactive effects of extraction parameters. A mathematical regression model was expressed properly by a quadratic second-order polynomial equation. The maximum oil yield (42.86%) from A. mexicana seeds was obtained with the optimal conditions (85?°C, 305?bar, 0.75?mm, 11?g/min, and 9% of flow rate-CO₂) of extraction parameters. The fatty acids analysis of the seed oil was done using gas chromatography and found its suitability as bio-fuel.     

Supercritical Carbon Dioxide Extraction and Characterization of Argentinean Chia Seed Oil

Extraction of chia seed oil was performed with supercritical carbon dioxide (SC-CO₂). To investigate the effects of pressure and temperature on the oil solubility and yield, two isobaric (250 and 450 bar) and two isothermal (40 and 60 °C) extraction conditions were selected. The global extraction yield of chia oil increased with pressure enhancement, but temperature had a little influence on it. The maximum oil recovery using SC-CO₂ at a mass flow rate of 8 kg/h was 97%, which was obtained at 60 °C, 450 bar for a 138-min extraction. The results showed that solubility changed from 4.8 g oil/kg CO₂ at 60 °C–250 bar to 28.8 g oil/kg CO₂ at 60 °C–450 bar. The final extract obtained by SC-CO₂ under different conditions and Soxhlet extraction contained mainly α-linolenic (64.9–65.6%) and linoleic (19.8–20.3%) acids. SC-CO₂ extraction is an interesting alternative methodology because it is possible to achieve a chia oil yield close to that obtained by conventional extraction with a similar fatty acid composition using an environmentally friendly process.     

Kinetics of supercritical carbon dioxide extraction of borage and evening primrose seed oil

In the present work, high‐pressure extraction of borage (Borago officinalis L.) and evening primrose (Oenothera biennis L.) seed oil, containing the valuable γ‐linolenic acid (GLA), has been investigated. Extraction was performed with supercritical carbon dioxide on a semi‐continuous flow apparatus at pressures of 200 and 300 bar, and at temperatures of 40 and 60 °C. A constant flow rate of carbon dioxide in the range from 0.17 to 0.20 kg/h was maintained during extraction. The extraction yields obtained using dense CO₂ were similar to those obtained with conventional extraction using hexane as solvent. The composition of extracted crude oil was determined by GC analysis. The best results were obtained at 300 bar and 40 °C for both seed types extracted, where the quality of oil was highest with regard to GLA content. The evening primrose seed oil extracted with supercritical fluid extraction was particularly rich in unsaturated fatty acids: up to 89.7 wt‐% of total free fatty acids in the oil. The dynamic behavior of the extraction runs was analyzed using two mathematical models for describing the constant rate period and the subsequent falling rate period. Based on the experimental data, external mass transfer coefficients, diffusion coefficients and diffusivity in solid phase were estimated. Results showed good agreement between calculated and experimental data.     

Quality of wheat germ oil extracted by liquid and supercritical carbon dioxide

The extraction of wheat germ oil by liquid and supercritical CO₂ is described from the point of view of both operative method and pretreatment of raw material. The best conditions for wheat germ oil extraction are: pressure, 150 bar; temperature, 40°C; and solvent flow rate, 1.5 L/min at standard temperature and pressure. The yields and fatty acid compositions obtained are very similar to those resulting from the conventional extraction process using hexane as solvent (8.0 wt%), although a higher-quality oil is obtained by using CO₂ as solvent (free fatty acids, 12.4%; tocopherol content, 416.7 mg tocopherol/g wheat germ oil). These factors lead to the conclusion that the extraction process using CO₂ could be economically competitive with the conventional process, since it considerably simplifies the oil refinement stages and completely eliminates the solvent distillation stage, which are the most costly processing steps in terms of energy consumption.     

Optimization of supercritical fluid extraction of phytosterol from roselle seeds with a central composite design model

Recovery of phytosterol from roselle (Hibiscus sabdariffa L.) seeds via supercritical carbon dioxide extraction modified with ethanol was investigated at pressures of 200–400 bar, temperatures from 40 to 80 °C and at supercritical fluid flow rates from 10 to 20 ml/min. It was found that an entrainer such as ethanol could enhance the solubility and extraction yield of roselle seed oil from the seed matrix, compared to values obtained using supercritical CO₂. After a typical run (holding period of 30 min, continuous flow extraction of 3 h), the results indicate that the oil recovery was optimal with a recovery of 108.74% and a phytosterol composition of 7262.80 mg kg^?1 at relatively low temperature of 40 °C, a high pressure of 400 bar and at a high supercritical fluid flow rate of 20 ml/min in the presence of 2 ml/min EtOH as entrainer. The solubility of roselle seed oil increased with temperature at the operating pressures of 200, 300 and 400 bar. Supercritical fluid extraction involved a short extraction time and the minimal usage of small amounts of entrainer in the CO₂.     

Supercritical CO2 extraction of ucuúba (Virola surinamensis) seed oil: global yield,kinetic data,fatty acid profile,and antimicrobial activities

Virola surinamensis is an abundant floodplain tree, popularly known as ucuúba, that grows in the Amazon. In this study, ucuúba seed oil was obtained by supercritical fluid extraction under different operating conditions, as well as Soxhlet extraction. The operating conditions for supercritical extraction were an extraction temperature of 40, 60, or 80?°C, a pressure of 350?bar, and a CO₂ mass flow of 7.9?×?10^?5 kg/s. The supercritical extraction curves were fitted to mass transfer models, and the fatty acid profiles of the extracts were determined by gas chromatography. The antimicrobial activity was assessed against Candida albicans, Staphylococcus aureus, and Escherichia coli. The highest yield obtained using supercritical CO₂ was 64.39% and the lowest was 59.21%. The phytochemical analysis showed the presence of steroids, terpenes, coumarins, and phenolic compounds. All ucuúba oil samples showed antioxidant activity. Regarding the antimicrobial activity, ucuúba oil only showed activity against S. aureus.     

Extraktion von Lupinenöl mit überkritischem Kohlendioxid

Extraction of Lupine Oil with Supercritical Carbon Dioxide Ground seeds of the South American lupine, Lupinus mutabilis SWEET, are treated with supercritical carbon dioxide at a pressure of 300 bar, a temperature of 40°C, and a throughput corresponding to 20 NL gas per g seed. Clear and slightly yellow lupine oil is obtained in almost quantitative yield. It is virtually free of lecithins and other phospholipids, whereas the oil extracted with hexane contains about 3% of such compounds. The two oils differ only slightly in their fatty acid compositions. Their alkaloid contents are also similar. Neither the yield of oil nor the extent of extraction of the various alkaloids is influenced by the water content of the ground seeds.     

Ethanol-Modified Supercritical Carbon Dioxide Extraction of the Bioactive Lipid Components of <Emphasis Type="Italic">Camelina sativa</Emphasis> Seed

Camelina sativa seed is an underutilized oil source that attracts a growing interest, but it requires more research on its composition and processing. Its high omega‐3 content and growing demand for clean food processing technologies make conventional oil extraction less attractive. In this study, the effect of extraction methods on the bioactive lipid composition of the camelina seed lipid was investigated, and its bioactive lipid composition was modified at the extraction stage using ethanol‐modified supercritical carbon dioxide (SC‐CO₂). Ethanol‐modified SC‐CO₂ extractions were carried out at varying temperatures (50 and 70 °C), pressures (35 and 45 MPa), and ethanol concentrations (0–10%, w/w), and were compared to SC‐CO₂, cold press, and hexane extraction. The highest total lipid yield (37.6%) was at 45 MPa/70 °C/10% (w/w) ethanol. Phospholipids and phenolic content increased significantly with ethanol‐modified SC‐CO₂ (p < 0.05). SC‐CO₂ with 10% (w/w) ethanol concentration selectively increased phosphatidylcholine (PC) content. Apparent solubility of camelina seed lipids in SC‐CO₂, determined using the Chrastil model, ranged from 0.0065 kg oil/kg CO₂ (35 MPa/50 °C) to 0.0133 kg oil/kg CO₂ (45 MPa/70 °C). Ethanol‐modified SC‐CO₂ extraction allowed modification of the lipid composition that was not possible with the conventional extraction methods. This is a promising green method for extraction and fractionation of camelina seed lipids to separate and enrich its bioactives.     

Antioxidant Activity and Total Polyphenols Content of Camellia Oil Extracted by Optimized Supercritical Carbon Dioxide

In this study, Camellia oil is co-extracted from Camellia oleifera seeds and green tea scraps by supercritical carbon dioxide (SC-CO₂), which is optimized on the extraction yield, ABTS-scavenging activity, and total polyphenols content (TPC) of oil by single-factor experiments combined with response surface methodology (RSM). The extraction temperature, pressure, dynamic time, carbon dioxide (CO₂) flow rate, and seed mass ratio were investigated with single-factor experiments. The results indicated the optimum CO₂ flow rate and dynamic extraction time were 15 L hour⁻¹ and 60 min (i.e., 2.382 kg CO₂/100 g sample). Furthermore, the complicated effects of extraction temperature (40–50 °C), pressure (20–30 MPa), and seed mass ratio (0.25–0.75) were optimized by RSM based on the Box–Behnken design (BBD). The models with high R-squared values were obtained and used to predict the optimum operating conditions of the process. Under the optimum operating conditions (i.e., temperature of 46 °C, pressure of 30 MPa, and seed mass ratio of 0.35), the extraction yield, ABTS-scavenging activity, and TPC of oil were 14.43 ± 0.17 g/100 g sample, 73.70 ± 0.34%, and 2.18 ± 0.05 mg GAE/g oil, which were in good agreement with the predicted values. In addition, the experiments indicated that the Camellia oil obtained was rich in polyphenols, resulting in better oxidation stability and antioxidant activity than the original oil.     

Comparison of two kinds of pumpkin seed oils obtained by supercritical CO2 extraction

The oils from two kinds of pumpkin seeds, black and white ones, were extracted by supercritical CO₂ (SC‐CO₂). The technological variables for SC‐CO₂ extraction were optimized and the resulting oils were analyzed by GC‐MS. As a result, the optimal conditions for SC‐CO₂ extraction were as follows: 25～30 MPa, 45 °C, SC‐CO₂ flow rate of 30～40 kg/h. The main compounds in the resulting oils were 9,12‐octadecadienoic acid, 9‐octadecenoic acid, stearic acid, palmitic acid for both types of pumpkin seeds, however, the black seed oil contains more unsaturated fatty acids (UFA) than the white seed oil. On the other hand, some compounds including heptadecanoic acid (0.27%), tetracosanic acid (0.1%), 9‐dodecaenoic acid (0.45%) and pentadecenoic acid (0.05%) were found in white seed oil but not in black seed oil; while eicosanic acid (0.05%), 11,14‐eicosadienoic acid (0.2%), 11‐octadecenoic acid (0.06%), 7‐hexadecenoic acid (0.02%) and 1,12‐tridecadiene (0.02%) were only found in black seed oil.     

A green separation process for recovery of healthy oil from pumpkin seed

In this study, pumpkin seeds, called as “Ürgüp Sivrisi” and grown in Cappadocia region, were used as plant materials because of high aroma contents. In the supercritical fluid extraction of pumpkin seed oil, the effect of main process parameters as the particle size (250-2360 μm), the volumetric flow rate of supercritical solvent (0.06-0.30 L/h), the operating pressure (20-50 MPa), the operating temperature (40-70 °C), the type of entrainer (ethanol and n-hexane) and those concentrations (0-10 vol.%) on the extraction yield, the oil solubility and the initial extraction rate were investigated. A cross-over effect for the extraction of pumpkin seed oil using supercritical CO₂ was determined at the operating pressure of 20-30 MPa. The maximum extraction yield obtained with entrainer free was reached 0.50 g oil/g dry seed at 600-1180 μm, 0.12 L/h, 50 MPa and 70 °C for the operation time of 5 h. The maximum extraction yield obtained with ethanol as an entrainer in the experiments was reached 0.54 g oil/g dry seed at the conditions of 600-1180 μm, 0.12 L/h, 30 MPa, 40 °C and 8 vol.% for the operating time of 2 h. The oil compositions were determined by gas chromatography analysis and the results showed that the compositions of pumpkin seed oil which were obtained by means of organic solvent extraction and supercritical fluid extraction were similar. The average oil compositions determined as 9.3 (±0.43)% palmitic acid, 7.5 (±0.6)% stearic acid, 32.3 (±0.6)% oleic acid, 48.1 (±0.6)% linoleic acid and 0.7 (±0.3)% linolenic acid. The morphological changes in the seeds were determined by the scanning electron microscopy analysis.     

Supercritical CO2 extraction of flaxseed

Extraction of flaxseed oil was performed with supercritical carbon dioxide (SC-CO₂). To investigate the effects of pressure and temperature on the solubility of oil and oil yield, three isobaric (21, 35, and 55 MPa) and two isothermal (50 and 70°C) extraction conditions were selected. Although the maximal solubility of flaxseed oil, 11.3 mg oil/g CO₂, was obtained at 70°C/55 MPa, the oil yield obtained after 3 h of extraction at this condition was only 25% (g oil/g seed×100), which represented 66% of the total available oil of the flaxseed. Lipid composition and FFA and tocol (tocopherol and tocotrienol) contents of the oils obtained by both SC-CO₂ and petroleum ether extraction were determined. The α-linolenic acid content of the SC-CO₂-extracted oil was higher than that obtained by solvent extraction.