Determination of oil content in oilseeds by analytical supercritical fluid extraction

The total oil content of soyflakes, canola seed and wetmilled corn germ were determined by analytical supercritical fluid extraction (SFE) with carbon dioxide as the extraction solvent. Results obtained by SFE were in excellent agreement with those obtained by a conventional Soxhlet technique with organic solvents. The analytical-scale SFE technique yielded average means within one standard deviation of the means derived from the organic solvent-based methodology. Matrices containing both high and low oil content were successfully extracted with carbon dioxide at comparable precision to that obtained with the standard procedure. The supercritical fluid-based technique appears to be a suitable replacement for traditional extraction methods with organic solvents, thereby potentially eliminating the costs associated with solvent disposal and exposure of laboratory personnel to toxic and flammable solvents. Presented at the 4th International Symposium on Supercritical Fluid Chromatography and Extraction, Cincinnati, Ohio, May 20–22, 1992.     

Quantitative extraction of pecan oil from small samples with supercritical carbon dioxide

A procedure to determine total oil content of pecan was developed for samples weighing 500 and 10 mg by supercritical fluid extraction (SFE) with carbon dioxide as the extraction solvent, and chilled hexane as the trapping solvent. Fatty acid methyl esters (FAMEs) were prepared from the total lipid fraction by using either an aliquot (500 mg starting weight) or the entire extract (10 mg starting weight). Total oil content obtained for either sample size with SFE was similar to that obtained with an organic solvent extraction technique. The fatty acid composition for the total lipid fraction of oils extracted with SFE was the same as for oils extracted with organic solvents, and oil composition did not change during SFE. Both oil yield and fatty acid composition were similar to those reported previously for pecan. Samples could be extracted and placed into FAME-derivatizing reagents in one day, and fatty acid composition of the total lipid fraction could be determined by gas-liquid chromatography the next day. The procedure, as demonstrated for pecan, should be suitable for other oilseeds, especially those containing low amounts of water.     

A Comparative Study on Response Surface Optimization of Supercritical Fluid Extraction Parameters to Obtain Portulaca Oleracea Seed Oil with Higher Bioactive Content and Antioxidant Activity Than Solvent Extraction

Portulaca oleracea (purslane) seed oil is a rich source of omega-6 and omega-3 fatty acids. Extraction of the purslane seed oil while preserving its high nutritive quality has been a challenge since conventional solvent extraction has many adverse effects on bioactive content. This study aims the optimization of purslane seed oil supercritical fluid extraction (SFE) conditions and to compare purslane seed oils obtained with SFE and conventional solvent extraction in terms of oil yield, along with the purslane seed oil quality and bioactive content. For this purpose, the SFE process parameters (pressure, temperature, static time, and dynamic time) are optimized for oil yield, omega-6, omega-3, and antioxidant activity using response surface methodology (RSM). Optimum SFE pressure, temperature, static time, and dynamic time levels are determined as 350 bar, 50 °C, 20 min, and 90 min, respectively. Oil yield and physicochemical quality properties of conventional solvent extract and SFE samples are determined and compared. Consequently, samples obtained via SFE and solvent extraction have similar quality properties. Distinctly, SFE allows an extraction with 5.6% higher total phenolic compound (TPC) and 33% higher antioxidant activity than solvent extraction. Practical Applications: In the study, the extraction of purslane oil using supercritical fluid extraction is optimized with different approaches. At optimum conditions, purslane oil is extracted and all physicochemical properties and the process efficiency (yield) are compared with the solvent-extracted samples. The results of this study make supercritical fluid extraction of purslane seed oil possible since all optimum operating conditions of a pilot-sized extractor are reported in the study. It is believed that the results provide a good starting point for industrial operations. Moreover, researchers also believe that research studies unveiling the new potential oil-bearing seeds are important to overcome the vegetable oil shortage that emerged this year.     

Development of Pressurized Extraction Processes for Oil Recovery from Wild Almond (Amygdalus scoparia)

Wild almond Amygdalus scoparia is a very fruitful tree that is spread over an extensive region of Iran. Considering its high quality oil, the development of clean extraction processes based on the use of compressed fluids is encouraged. In this study, the main factors involved in supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) of wild almond have been optimized by using two different experimental designs and considering the oil extraction yield as a response variable; effects of time, temperature, pressure, and use of co‐solvents were studied for SFE while effects of time, temperature and type of solvent were evaluated for PLE. Results showed that the maximum oil yield using supercritical carbon dioxide was 42 %, obtained under the following conditions: extraction temperature, 40 °C; extraction pressure, 40 MPa; and 10 % ethanol as co‐solvent. The optimum extraction yield for PLE was 55 %, which was achieved using ethanol as solvent at 150 °C for 20 min. Lipidomic analysis revealed that the amount of oleic acid in the oil extracted by SFE was higher than those obtained by using other classical procedures. In addition, triacylglycerols constituted more than 98 % of the extracted oils.     

Extraction of Hydrocarbons from Crude Oil Tank Bottom Sludges using Supercritical Ethane

Abstract

A custom‐built, solvent recirculating, supercritical fluid extraction (SFE) apparatus was used to study the extraction of hydrocarbons from a crude oil tank bottom sludge (COTBS) with supercritical ethane. The SFE experiments were carried out varying the pressure (10 MPa and 17.20 MPa) and temperature (35°C and 65°C). The yield of the extracted hydrocarbon fraction increased with increase in extraction pressure at constant temperature, and decreased with increase in extraction temperature at constant pressure. The maximum extraction yield was obtained at the pressure and temperature conditions that lead to the highest solvent density. The extracted hydrocarbon fraction was a significantly upgraded liquid relative to the original untreated COTBS.     

Supercritical fluid extraction of wormwood (Artemisia absinthium L.)

The objective of the work was to optimize the extraction of wormwood oil by supercritical fluid extraction (SFE) of growth-controlled plant material. Different extraction conditions, two growth techniques and various crops were tested and the evolution of the extracted oil composition was screened chromatographically. A comparison with conventional techniques such as hydrodistillation (HD) or organic solvent extraction (OSE) was also presented. Particularly, six CO₂ densities ranging from 285.0 kg/m³ to 819.5 kg/m³ were studied in the range of 9.0-18.0 MPa and 40-50 °C. A systematic study was carried out with plant material from 2005, while SFE of 2006, 2008 and aeroponically grown crops was performed for comparative purposes. The effect of ethanol as a modifier of the supercritical fluid extraction was also studied. The major compounds found in the SFE extracts as well as in the HD essential oils were Z-epoxyocimene, chrysanthenol and chrysanthenyl acetate. A model based on mass transfer equations, the Sovová model, was successfully applied to correlate the experimental data.     

Effect of various extraction conditions on the phenolic contents of pomegranate seed oil

Pomegranate seeds are byproducts of the pomegranate juice industry. Because of the presence of large amounts of certain pharmaceutical and nutraceutical components in the seeds, a proper extraction method to obtain these components is highly demanded in the food industry. In this study, the effect of different extraction methods on the total phenolic contents of the oil extracted from pomegranate seeds of the Malas variety from Shahreza, Iran, was investigated. Four different extraction methods including normal stirring, Soxhlet, microwave irradiation and ultrasonic irradiation using two types of organic solvents as well as a supercritical fluid extraction (SFE) method using CO₂ as solvent were applied. The different organic solvents of this study did not indicate any significant differences in the total phenolic contents of the extracted oils, but the extracted oils from the various conditions of SFE indicated wide changes in the amount of phenolic compounds (7.8–72.1 mg/g). The total phenolic content of the extracted oil from one of the SFE runs was several times greater than those in the extracted oils using organic solvents.     

Extraction of essential oil from geranium (Pelargonium graveolens) with supercritical carbon dioxide

This study investigated the supercritical fluid extraction (SFE) of geranium essential oil from geranium (Pelargonium graveolens) using supercritical carbon dioxide solvent. The extraction yield was measured as a function of pressure, temperature and carbon dioxide flow rate. At low pressure (10 MPa) and high temperature (343 K), waxes were co‐extracted with the essential oil, resulting in artificially elevated essential oil extraction yields as no method was available with the SFE apparatus used to separate co‐extracted waxes and oil. At high pressure (30 MPa) and low temperature (313 K), the amount of wax co‐extracted decreased. Under these ‘optimum’ conditions, the extraction yield increased with decrease in flow rate giving a maximum extraction yield of 2.53%. All samples were analyzed by gas chromatography–mass spectrometry and the effect of pressure and extraction time on oil composition was studied. The percentage compositions of terpene hydrocarbons, terpenols, geraniol and geranyl esters were significantly affected by pressure and extraction time. The oil samples obtained by SFE were also compared with commercially obtained steam distilled samples. All major components of the commercially obtained oils were present in the SFE‐obtained oils; however, the percentage composition of the major components differed greatly between steam distilled and SFE oils. Copyright © 2005 Society of Chemical Industry     

超临界CO_2和微波辅助萃取当归挥发油

考察当归挥发油的不同提取方法。文中用超临界CO2流体萃取法和微波辅助萃取法研究萃取当归挥发油。实验表明:超临界CO2萃取最佳工艺条件为萃取压力25 MPa、分离釜Ⅰ解析温度55℃、萃取温度45℃,提取率约1.9%;微波辅助萃取最佳工艺条件为无水乙醇为提取溶剂,微波功率800 W、微波辐射时间150 s、液料质量比为4.71∶1,提取率约11.2%。微波辅助萃取法取得当归油的收率高于超临界CO2萃取法。微波辅助萃取法萃取当归挥发油收率高,但外观品质较超临界萃取的当归挥发油差。     

Chromenes from Ageratum conyzoides: Steam distillation,supercritical extraction,and mathematical modeling

The chromenes extraction processes from Ageratum conyzoides by steam distillation and supercritical fluid extraction (SFE) were studied. Essential oil was extracted by saturated steam at 1.0 to 2.0 bar and the SFE was performed at 40ºC and 90 to 200 bar to obtain non-volatile extracts. The essential oil presented two major compounds—precocene I (28.24%) and precocene II (28.55%). At 90 bar, the SFE resulted in higher yield and selectivity for precocene I and II (65.06%). The yield of chromenes varied according to pressure of SFE; however, this behavior was not observed in extracts obtained by steam distillation.     

Supercritical fluid extraction and characterisation of oil from hazelnut

Hazelnut (Corylus avellana L.) oil was extracted with compressed carbon dioxide in the temperature range of 308—321 K and in the pressure range of 18—23.4 MPa. In addition the influence of the superficial velocity, within a tubular extractor was studied. Physical and chemical characteristics of the oil were obtained. The results including contents of free fatty acids, sterols, triacylglycerols and tocopherols were compared with those obtained when n‐hexane was used as solvent. No significant differences were found when the oils extracted by both methods were analysed. The main fatty acid was the oleic acid (83—85%), followed by linoleic acid (6—8%) and palmitic acid (5—6%). The main triglyceride found in hazelnut oils was the trioleylglycerol (OOO) (63.4—69.6%), followed by the linoleyl‐dioleylglycerol (LOO) (11.6—15.5%) and palmitoyl‐dioleylglycerol (POO) (9.9—10.4%). In terms of sterols, the main component was β‐sitos‐terol (∼83%) followed by campesterol (∼6%). The amount of cholesterol was very low (∼0.2%). The CO₂ extracted oil contained about 17% more tocopherols (458.7 μg/g oil) than the oil extracted by n‐hexane (382.8 μg/g). Oxidative stability was studied by using the induction time determined by the Rancimat method. The oil obtained by supercritical fluid extraction (SFE) was slightly more protected against oxidation (8.7 h for SFE extracted oil and 6.7 h for the hazelnut oil extracted with n‐hexane). Both oils presented high stability index values (7.81 for the oil extracted by n‐hexane and 8.7 for the oil extracted with supercritical CO₂). Oil extracted by supercritical CO₂ was clearer than the one extracted by n‐hexane, showing some refining. Besides, the acidity index was 1.6 for the n‐hexane extracted oil and 0.9 for the oil extracted with supercritical carbon dioxide. The central composite non‐factorial design was used to optimise the extraction conditions, using the Statistica, version 5 software (Statsoft). The best results, in terms of recoveries of hazelnut oil by SFE, were found at 22.5 MPa, 308 K and superficial velocity of 6.0 × 10^—4 ms^—1.     

八角茴香油的提取工艺和香气性能

以八角茴香果为原料,比较了超临界CO2流体萃取法(SFE)和水蒸气蒸馏法(SD)对八角茴香油的提取率和香气性能的影响。用正交设计方法,确定了超临界CO2流体萃取八角茴香油的最佳条件为:萃取压力13.8MPa,萃取温度40℃,萃取时间2 h。在该条件下,八角茴香油的萃取率为2.88%。相同的萃取条件下,用水蒸气蒸馏技术提取八角茴香油,精油萃取率为1.39%。通过气味指纹分析仪(电子鼻)检测和气味感官评定,对两种提取方法得到的八角茴香油的香气性能进行了比较,用SFE法所得八角茴香油的质量比SD法所得精油有明显改善,香气更完全,更具新鲜感和天然感。     

From supercritical carbon dioxide to gas expanded liquids in extraction and chromatography of lipids

Analytical‐scale extraction and chromatography of oils, fats and other liposoluble compounds can be achieved by using supercritical carbon dioxide as a solvent. Since the 90's when supercritical fluid chromatography (SFC) was a hot topic, this technology has developed into a robust, modern analytical technique that uses any proportions of compressed CO₂ mixed with an organic solvent. Supercritical fluid extraction (SFE) on the other hand is only recently starting to reform in a similar way, towards the use of more robust extraction system and enabling mixing of compressed CO₂ with larger proportions of organic solvents. In this Feature article, the development of SFC and SFE into what options we have today is described, including the latest trend of using CO₂‐expanded liquid (CXL) as extraction solvent for lipids.     

超临界流体萃取脱除人参中痕量有机氯农药

利用在线固相吸附柱收集,淋洗剂洗脱超临界流体萃取出的真实人参样品中的有机氯农残实验,确定最佳的吸附柱和淋洗剂。通过实验确定利用C18作吸附剂,用正己烷洗脱可取得最优效果。此外,还对直接冷凝收集法、索氏提取法与固相吸附柱收集法进行了对比。     

Application of response surface methodology for the optimization of supercritical carbon dioxide extraction and ultrasound-assisted extraction of Capparis spinosa seed oil

Caper (Capparis spinosa) seed oil growing wild in Iran was extracted using supercritical CO₂ and ultrasound-assisted extraction methods. The experimental parameters of SFE and UAE were optimized using a rotatable central composite design. The highest yield for SFE was obtained at a pressure of 355 bar, temperature of 65 °C, modifier volume of 140 μL, static and dynamic extraction time of 10 and 35 min, respectively, and for UAE was gained at solvent volume of 23 mL, sonication time of 45 min and temperature of 40 °C. This resulted in a maximum oil recovery of 25.1% and 27.9% for SFE and UAE, respectively. The extracts with higher yield from both methods were subjected to transesterification and GC–MS analysis. SFE and UAE processes selectively extracted the fatty oils with high percentage of omega-6 and omega-9-fatty acids. The major components of the extracted oils from both methods were linoleic, oleic, its positional isomer cis-vaccenic and Palmitic acid.     

Preparative-scale supercritical fluid extraction/supercritical fluid chromatography of corn bran

A preparative-scale supercritical fluid extraction/supercritical fluid chromatography (SFE/SFC) procedure has been developed for the removal of oil from corn bran to obtain fractions enriched with free sterols and ferulate-phytosterol esters (FPE). Operational parameters from an analytical-scale supercritical fluid fractionation technique were translated to and optimized on a home-built, preparatory-scale SFE/SFC apparatus. SFE was performed at 34.5 MPa and 40°C using supercritical carbon dioxide. These conditions did not result in exhaustive extraction of the corn bran, but yielded about 96% of the available oil. SFC was conducted in three steps, followed by reconditioning of the sorbent bed. Preparative-scale SFE/SFC of corn bran produced a fraction enriched greater than fourfold in free sterols and 10-fold in FPE, suggesting that such a scheme could be used industrially to produce a functional food ingredient.     

中国几种油页岩超临界萃取研究

用甲苯为溶剂对八种中国油页岩样进行了非等温的超临界萃取实验.进行了不同萃取压力、终温、样品粒度、溶剂速率和溶剂中供氢组分含量等参数的系统实验.结果表明,甲苯溶剂超临界萃取油类产物产率是一般干馏方法的二倍.溶剂中加入供氢组分,能使油页岩中有机质回收完全.由不同温度下萃取溶液中萃取物浓度的变化得出,油页岩的超临界萃取动力学可用一级反应描述,过程分两段,活化能分别为120和180kJ·mol~(-1)左右.     

Comparison of a supercritical fluid extraction method for the extraction of oilseeds with the DGF standard method B-I 5 (87)

Three different oilseeds, rapeseed, sunflower, and soybeans are extracted by SFE (supercritical fluid extraction). As parameter for the extraction conditions the extracts are analyzed regarding the contents of tocopherols, and as parameter for the content of more polar lipids the contents of diglycerides and free fatty acids are analyzed. The extraction temperature has a significant influence on the determined oil content, the content of tocopherols, diglycerides, and free fatty acids. With increasing temperature the oil content increases. The content of tocopherols, diglycerides, and free fatty acids increases up to 75 °C. At 100 °C the content of diglycerides and free fatty acids decreases and the content of tocopherols shows no appreciable changes. The optimal extraction conditions are described and the results of the determination of the oil content under optimal conditions are compared with the results of the DGF standard method B-I 5 (87). The oil contents investigated with both methods correspond well. The content of tocopherols is significantly higher in the oil of rapeseed and soybeans extracted by SFE, whereas the content of diglycerides and free fatty acids varied in dependence on the oilseed.     

Supercritical fluid extraction and bioassay identification of prodrug substances from natural resources

For arbitrarily chosen thirty types of natural resources which have been widely used in oriental traditional herb medicine, supercritical CO₂ extraction (SFE) and organic liquid solvent extraction (LSE) withn-hexane, chloroform and methanol were carried out to extract pharmaceutical substances. To evaluate relative advantages and shortcomings between the SFE and LSE, five types of bioactivity assays as well as gas- and thin layer-chromatographic analysis were performed for all the extracts obtained by the two extraction methods. Types of bioassays performed included cytotoxicity, bleb forming, DNA binding, oxygen free radical scavenger and Xanthine oxidase inhibitor tests. To evaluate economic viability of the SFE over the traditional LSE, extractability of prodrug substances was evaluated as the functions of extraction temperature and pressure. SFE was proven to be a feasible alternative over LSE. Also, the optimum SFE conditions which provided maximum extraction and cytotoxicity for each selected sample were presented.     

Concentration of phytosterols for analysis by supercritical fluid extraction

Fractionation of sterols from plant lipid mixtures was accomplished using a multistep supercritical fluid extraction (SFE) procedure. Samples of seed oils, margarine, corn germ oil, and corn fiber oil were extracted to yield enriched phytosterol fractions. Supercritical fluid chromatography (SFC) was utilized to separate and determine the concentration of the plant sterols in the extracts from the various samples. The sterol concentration in the original samples varied from 2.2 mg/g in soybean oil to 13.2 mg/g in oil extracted from corn fiber. After the SFE-based fractionation of the samples, the sterol concentration was increased to 64.4 mg/g in the extract from soybean oil and 166.2 mg/g in the extract from corn fiber oil. Oil extracted from corn bran, which measured 8.6 mg/g in the original oil, increased to 322.2 mg/g using the fractionation process. The benign conditions utilized by SFE and SFC proved to be effective for the analyses of these compounds without inducing degradation of the analytes.