Investigation of the technological properties ofNigella sativa (black cumin) seed oil

Three commercially cultivatedNigella sativa seed varieties of Turkish origin were analyzed, and the characteristics and constituents of the seed oils were reported. Presence of lipase enzyme in seed results in enzymatic hydrolysis at ordinary temperature; the free acid content of oil may increase up to 40% or higher. Black cumin seed oil might serve as a source of semi-drying oil and fatty acids of technical grade, and the removal of free fatty acids from oil and the recovery of fatty acids were investigated.     

超临界CO_2流体萃取植物油的实验研究

建立了一套超临界流体萃取实验装置,就大豆和花生两种植物油超临界流体萃取进行了较为详细的实验研究.在探讨了压力、温度、颗粒度、空隙率以及时间等对萃取率的影响之后,获得了指导实际生产的最佳工艺参数条件.     

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.     

Pilot-scale supercritical carbon dioxide extraction and fractionation of wheat germ oil

There is a need for the development of new processing techniques to facilitate vegetable oil extraction and refining while sustaining the nutritional components naturally present in edible oils and reducing the adverse impact of oil processing on the environment. In this study supercritical carbon dioxide (SC−CO₂) extraction and fractionation techniques were examined as alternative methods to obtain wheat germ oil (WGO) of high quality and purity. It was shown that the SC−CO₂ extraction technique is effective in extraction of WGO. There was no significant difference in the FA composition of SC−CO₂- and hexane-extracted WGO. Both hexane-and SC−CO₂-extracted WGO were rich in α-tocopherol. Moisture content of the SC−CO₂-extracted oil was higher than that of the hexane-extracted oil. Solvent/feed ratio had a significant effect on the SC−CO₂ extraction yields. This study demonstrated that supercritical fluid fractionation was a viable process to remove FFA efficiently from both hexane-and SC−CO₂-extracted WGO while retaining bioactive oil components in the final product.     

Continuous supercritical carbon dioxide processing of palm oil

Crude palm oil was processed by continuous supercritical carbon dioxide. The process reduces the contents of free fatty acids, monoglycerides and diglycerides, certain triglycerides, and some carotenes. The refined palm oil from the process has less than 0.1% free fatty acids, higher carotene content, and low diglycerides. Solubility of palm oil in supercritical carbon dioxide increased with pressure. A co-solvent improves the refining process of palm oil.     

Supercritical carbon dioxide extraction ofDimorphotheca pluvialis oil seeds

The possibility of extraction ofDimorphotheca oil with supercritical carbon dioxide is demonstrated in this article. Before extraction, the seeds have to be pretreated to improve extraction yield. Experiments showed that the best pretreatment procedure forDimorphotheca was heating the seeds under reduced pressure to 100°C for 60 min, followed by flaking or milling. To give an impression about the efficiency of the supercritical extraction, a mathematical model has been developed to estimate the overall mass transfer coefficient (A _p K). Also, an empirical relation betweenA _p K and the interstitial velocity has been found. The physical properties of the supercriticalDimorphotheca oil are in good agreement with those of conventionally extracted oil, except for a lower phospholipid content. It is expected that further refining of supercriticalDimorphotheca oil will be marginal.     

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.     

The kinetics of hydrolysis ofNigella sativa (black cumin) seed oil catalyzed by native lipase in ground seed

Kinetics of the lipolysis ofNigella sativa oil catalyzed by native lipase in crushed seed were studied between 20 and 90°C. Data fitted the pseudo first-order rate equation at 20, 30 and 40°C; and the pseudo second-order equation at 50, 60 and 70°C, but neither equation fit at 80 and 90°C. Lipolysis approximated first-order with respect to water.     

超临界二氧化碳萃取葡萄籽油工艺优化

为了回收利用葡萄酒酿造过程产生的副产品中的有效成分,本文利用超临界CO₂萃取技术从葡萄籽中提取含有不饱和脂肪酸的葡萄籽油,意在考量超临界CO₂技术在萃取葡萄籽油方面的作用。设计单因素实验,研究了萃取压力、萃取温度、CO₂流量以及停留时间对葡萄籽油萃取率的影响。单因素实验结果表明萃取压力对萃取结果的影响最为显著。萃取温度和CO₂流量对萃取率的影响都存在最佳值,当温度和流量超过最佳值,萃取率开始降低。在单因素实验的基础上进行响应面实验,采用中心复合设计进行实验方案设计以优化萃取葡萄籽油工艺。对响应面实验结果进行方差分析,建立多元回归模型,模型P值<0.0001,预测超临界CO₂萃取葡萄籽油的最佳萃取条件为：萃取压力28MPa、萃取温度321 K、CO₂流量15.5L/h,停留时间155min,萃取率达到14.12%。     

超临界CO_2萃取水冬瓜油

研究了用超临界ＣＯ２流体从水冬瓜果实中提取油品的工艺,探索了操作压力、温度、流量及时间对水冬瓜油的萃取率的影响。分析了萃取条件与油品质量的关系,并综合得出了超临界ＣＯ２萃取水冬瓜油的最佳萃取条件。     

超临界CO_2萃取青皮挥发油的工艺研究

采用正交实验法对超临界CO2萃取中药青皮挥发油的最佳工艺条件进行优选。以挥发油得率为考察指标,探讨了萃取压力、萃取温度、萃取时间三因素在不同水平下对青皮挥发油得率的影响,并与水蒸气蒸馏法进行了比较。研究表明,萃取压力对挥发油得率有显著影响,萃取温度及时间影响不显著,各因素作用主次关系为:压力>温度>时间。优选得到的最佳工艺为:萃取压力25 MPa,萃取温度35℃,萃取时间1.5 h,得率为1.3197%,比水蒸气蒸馏法提高2.4倍,时间减少78.57%。超临界CO2萃取收率高、耗时短、品质好。     

Effects of different nitrogen doses on thymoquinone and fatty acid composition in seed oil of black cumin (Nigella sativa L.)

Black cumin, Nigella sativa L. belonging to Ranunculaceae, is a valuable medicinal plant because of the curative effects of seed and oil. Despite studies on black cumin, there are few studies on the effects of nitrogen on fatty acid composition, no records on thymoquinone yield, and the thymoquinone content of the seed oil. In this study, the effects of different nitrogen doses on the seed oil yield, thymoquinone ratio/yield, and fatty acid compositions were investigated. Field studies with nitrogen doses (0, 40, 60, 80, and 100 kg/ha) were studied using the randomized plot design. As a result of the research, nitrogen doses significantly affected the oil and thymoquinone yields while insignificant on the thymoquinone ratio. The highest oil yield with 501.6 kg/ha was obtained from 80 kg/ha of the nitrogen doses, while the highest thymoquinone yield with 10.24 kg/ha was obtained from the control plots. Thymoquinone yields were in the same statistical group with other nitrogen doses, except for means of 100 kg/ha nitrogen doses. Linoleic, oleic, and palmitic acids were major fatty acids of black cumin, and their variations were insignificant in nitrogen applications. The values of butyric, capric, and linolenic acids varied significantly in different nitrogen doses. As a result of the study, it was determined that the highest oil yield was obtained from 80 kg/ha nitrogen application. It has been determined that nitrogen doses above 60–80 kg/ha should be avoided for the seed oil and thymoquinone yields in black cumin.     

Characterization and supercritical carbon dioxide extraction of walnut oil

Walnut (Juglans regia L.) oil was extracted with compressed carbon dioxide (CO₂) in the temperature range of 308 to 321 K and in the pressure range of 18 to 23.4 MPa. The influence of particle size was also studied at a superficial velocity of 0.068 cm/s, within a tubular extractor of 0.2 L capacity (cross-sectional area of 16.4 cm²). FFA, sterol, TAG, and tocopherol compositions were not different from those of oil obtained with n-hexane. The main FA was linoleic acid (56.5%), followed by oleic acid (21.2%) and linolenic acid (13.2%). The main TAG was LLL (linoleic, linoleic, linoleic) (24.4%), followed by OLL (oleic, linoleic, linoleic) (19.6%) and LLLn (linoleic, linoleic, linolenic) (18.4%). The main component of sterols was β-sitosterol (85.16%), followed by campesterol (5.06%). The amount of cholesterol was low (0.31 and 0.16% for oils extracted by n-hexane and supercritical fluid extraction, respectively. The CO₂-extracted oil presented a larger amount of tocopherols (405.7 μg/g oil) when compared with 303.2 μg/g oil obtained with n-hexane. Oxidative stability determined by PV and the Rancimat method revealed that walnut oil was readily oxidized. Oil extracted by supercritical CO₂ was clearer than that extracted by n-hexane, showing some refining. A central composite, nonfactorial design was used to optimize the extraction conditions using the software Statistica, Version 5. The best results were found at 22 MPa, 308 K, and particle diameter (Dp) −0.1 mm.     

Extraction of rice brain oil using supercritical carbon dioxide and propane

Extraction of rice bran lipids was performed using supercritical carbon dioxide (SC−CO₂) and liquid propane. To provide a basis for extraction efficiency, accelerated solvent extraction with hexane was performed at 100°C and 10.34 MPa. Extraction pressure was varied for propane and SC−CO₂ extractions. Also, the role of temperature in SC−CO₂ extraction efficiency was investigated at 45,65, and 85°C. For the SC−CO₂ experiments, extraction efficiencies were proportional to pressure and inversely proportional to temperature, and the maximal yield of oil achieved using SC−CO₂ was 0.222±0.013 kg of oil extracted per kg of rice bran for conditions of 45°C and 35 MPa. The maximal yield achieved with propane was 0.224±0.016 kg of oil per kg of rice bran at 0.76 MPa and ambient temperature. The maximum extraction efficiencies of both SC−CO₂ and propane were found to be significantly different from the hexane extraction baseline yield, which was 0.261±0.005 kg oil extracted per kg of rice bran. A simulated economic analysis was performed on the possibility of using SC−CO₂ and propane extraction technologies to remove oil from rice bran generated in Mississippi. Although the economic analysis was based on the maximal extraction efficiency for each technology, neither process resulted in a positive rate of return on investment.     

Supercritical carbon dioxide extraction of lipids from Pythium irregulare

Lipids that contain polyunsaturated fatty acids (PUFA) have therapeutic value. PUFA, however, degrade in high-temperature, oxygen-rich conditions typical of conventional hot solvent-extraction and distillation methods. Supercritical CO₂ extraction was chosen as an alternative method to recover these valuable compounds from the lower fungus, Pythium irregulare. Freeze-dried biomass was subjected to an aqueous phase and placed into a flow-through extraction apparatus. Extraction of oil from this biomass showed some success for moisture contents as high as 30% (wet basis). The addition of a novel CO₂-philic surfactant to the wet biomass with moisture contents as high as 95% (wet basis) increased the extraction rate of fungal oil by more than an order of magnitude. For tests with extraction times of 5 to 6 h, data for the diffusion-controlled region were modeled with an analytical solution to Fick’s second law. Equilibrium data were also obtained for the fungal oil at two isotherms (40 and 60°C) over a pressure range of 13.7 to 27.5 MPa.     

Comparison of processes for the supercritical carbon dioxide extraction of oil from soybean seeds

Three different process alternatives for the production of soybean oil by supercritical carbon dioxide extraction were analyzed. The first two processes were organized according to the classical scheme, based on high-pressure extraction followed by separation induced by pressure reduction. Different techniques were used to recover the solvent in these two schemes, in the liquid and in the gas phases, respectively. The third alternative was based on an isobaric scheme—the oil, extracted at high pressure, was separated by chainging the temperature in the separator. In a further improvement, a technique for the heat transfer network integration was added to all the process schemes. The different schemes were used to establish the process configuration that can produce a lower operating cost for soybean oil extraction. Operating costs were considered on an industrial scale to carry out a screening of the different alternatives. The operating cost of these plants were then compared with the hexane extraction process. A substantial reduction in the specific costs was obtained in the case of heat transfer integration, and the operating costs fell in the same range as conventional extraction plants.     

Lipase-catalyzed alcoholysis of cod liver oil in supercritical carbon dioxide

Enzymatic alcoholysis of cod liver oil, with an immobilized lipase, was carried out in supercritical carbon dioxide. The enzyme was catalytically active under the experimental conditions used. The reaction medium was investigated to preferentially extract ethyl esters, synthesized during the course of the experiment, from the unconverted cod liver oil substrate and side-products. The effect of pressure changes on the amount of tri-, di-, and monoglycerides and ethyl esters, present in both the extract and the remaining lipid residue, was determined. Furthermore, the fatty acid compositions of the lipid classes were analyzed, and the relative amounts of both eicosapentaenoic acid and docosahexaenoic acid to palmitic acid were determined. The results show that it is possible to preferentially extract the synthesized ethyl esters at low pressures. The extract collected at 9 MPa contained 64 g ethyl esters/100 g extract, while the total amount of all other lipid classes detected was 19 g/100 g extract. As the pressure was increased, the relative amount of the other lipid classes detected in the extract, especially triglycerides, was enhanced. The relative amounts of both eicosapentaenoic acid and docosahexaenoic acid to palmitic acid increased for some lipid classes in the extract. This increase was most pronounced for the monoglyceride lipid class. The integration of biocatalysis and product fractionation, applied in this study, suggests that the potential for biocatalysis in industrial processes is considerably wider than had been thought.     

Solubility model of arachis hypogea skin oil by modified supercritical carbon dioxide

The main objective of this study was to determine the solubility of peanut (Arachis Hypogea) skin oil using modified supercritical carbon dioxide (SCCO₂). The solubility was measured at pressure ranging from 100 to 300 Bar, temperature of 313 to 328 K, and rate of modifier from 0.075 to 0.225 mL/min. The solubility of extraction was ranging from 1.12 to 7.73 mg/min. The Chrastil, modified Chrastil, Del Valle Aguilera (DVA), Adachi-Lu, and Gordillo as empirical models were tested to fit the experimental data. Solubilities from these models followed the average absolute relative deviations (AARD) from experimental data: Chrastil, modified Chrastil, DVA, Adachi-Lu, and Gordillo with AARD of 8.54%, 8.26%, 19.41%, 9.24%, and 20.62%, respectively. Modified Chrastil model provide the best fit.     

超临界CO2萃取丁香油的数值模拟

为了预测超临界CO₂萃取挥发油动态过程,根据挥发油在超临界CO₂与物料之间的质量传递平衡,采用集总参数法建立超临界CO₂萃取丁香油过程的数学模型。结合不同温度、压力、粒径和CO₂流速条件下的实验结果,对方程进行了合理的简化,并利用实验数据拟合出模型中CO₂密度、粒径和流速的系数。验证结果表明模型的计算值和实验值的平均相对误差在6. 88%～57. 78%之间,建立的数值模型能较好地描述实际的超临界CO₂萃取丁香油行为。     

Lipase-catalyzed alcoholysis with supercritical carbon dioxide extraction 1: Influence of flow rate

A combined process of lipase (E.C. 3.1.1.3) catalysis and extraction of product with supercritical carbon dioxide was studied. The effect of different flow rates of the extraction fluid on the selective removal of the ethyl esters (EE) synthesized in a lipase-catalyzed alcoholysis of cod liver oil with ethanol was investigated. The faster the flow rate, the faster the extraction rate and the higher the recovery of EE. For example, after a 270-min extraction, the total recovery of EE was 1520 mg for a flow rate of 0.3 liter carbon dioxide at atmospheric pressure and room temperature/min (NL/min) as compared to 250 mg when 0.015 NL/min was used. The concentration of EE in the carbon dioxide was found to decrease with increasing flow rate, which indicates that the rate of diffusion of EE limits their extraction at fast flow rates. A high flow rate was found to result in a more selective extraction of EE, i.e., less amounts of other lipid components present in the reaction mixture were coextracted with the EE. Further, by increasing the flow rate, the equilibrium of the reaction was shifted slightly toward ester synthesis. An increase in the flow rate from 0.015 to 0.075 NL/min resulted in an approximately 10% increase in total conversion (from 73 to 82%), whereas only a negligible increase was obtained when the flow rate was increased further to 0.15 NL/min.