Optimization of a supercritical fluid extraction/reaction methodology for the analysis of castor oil using experimental design

The aim of this work was to optimize a supercritical fluid extraction (SFE)/enzymatic reaction process for the determination of the fatty acid composition of castor seeds. A lipase from Candida antarctica (Novozyme 435) was used to catalyze the methanolysis reaction in supercritical carbon dioxide (SC-CO(2)). A Box-Behnken statistical design was used to evaluate effects of various values of pressure (200-400 bar), temperature (40-80 degrees C), methanol concentration (1-5 vol %), and water concentration (0.02-0.18 vol %) on the yield of methylated castor oil. Response surfaces were plotted, and these together with results from some additional experiments produced optimal extraction/reaction conditions for SC-CO(2) at 300 bar and 80 degrees C, with 7 vol % methanol and 0.02 vol % water. These conditions were used for the determination of the castor oil content expressed as fatty acid methyl esters (FAMEs) in castor seeds. The results obtained were similar to those obtained using conventional methodology based on solvent extraction followed by chemical transmethylation. It was concluded that the methodology developed could be used for the determination of castor oil content as well as composition of individual FAMEs in castor seeds.     

Comparison of eucalyptus camaldulensis Dehn. oils from Mozambique as obtained by hydrodistillation and supercritical carbon dioxide extraction

Leaf oils of E. camaldulensis Dehn. from Mozambique obtained by hydrodistillation and by supercritical carbon dioxide extraction under different conditions were compared with regard to their major components. The oil obtained by hydrodistillation showed high concentrations of 1,8-cineole (43%), alpha-pinene (5.5%), beta-pinene (3.4%), p-cymene (5.2%), terpinen-4-ol (3.1%), and globulol (4.1%). The extracts obtained by supercritical carbon dioxide extraction have lower amounts of 1,8-cineole, alpha-pinene, beta-pinene, and terpinen-4-ol, but have higher amounts of allo-aromadendrene and globulol. At the same time, distilled oil of E. radiata was extracted from an inert matrix (Celite) and the extract showed a higher content of 1,8-cineole at 80 bar and 60 degrees C than the feed, suggesting that a multiple-stage supercritical carbon dioxide extraction of the E. camaldulensis studied can produce an oil close to the market requirements set by the European pharmacopoeias.     

Characterization of medium-chain triacylglycerol (MCT)-enriched seed oil from Cinnamomum camphora (Lauraceae) and its oxidative stability

Medium-chain triacylglycerol (MCT)-enriched oil was extracted by supercritical fluid extraction of carbon dioxide (SFE-CO(2)) from Cinnamomum camphora seeds. The SFE-CO(2) process was optimized using the Box-Behnken design (BBD). The maximum oil yield (42.82%) was obtained under the optimal SFE-CO(2) conditions: extraction pressure, 21.16 MPa; extraction temperature, 45.67 °C; and extraction time, 2.38 h. Subsequently, the physicochemical characteristics, fatty acid composition, triacylglycerol (TAG) composition, tocopherol content, and DSC profile as well as oxidative stabilities of C. camphora seed oil (CCSO) were studied. Results showed that CCSO contained two major medium-chain fatty acids, capric acid (53.27%) and lauric acid (39.93%). The predominant TAG species in CCSO was LaCC/CLaC (ECN 32, 79.29%). Meanwhile, it can be found that CCSO had much higher oxidative stabilities than coconut oil due to the higher content of tocopherols in CCSO (α-tocopherol, 8.67 ± 0.51 mg/100 g; γ-tocopherol, 22.6 ± 1.02 mg/100 g; δ-tocopherol, 8.38 ± 0.47 mg/100 g). Conclusively, CCSO with such a high level of MCTs and high oxidative stabilities could be potentially applied in special food for specific persons such as weak patients and overweight persons because oils enriched in MCTs can be rapidly absorbed into body to provide energy without fat accumulation.     

Pressurized fluids for extraction of cedarwood oil from Juniperus virginianna

The extraction of cedarwood oil (CWO) using liquid carbon dioxide (LC-CO(2)) was investigated and compared to supercritical fluid extraction, including the effects of extraction pressure and length of extraction. The chemical composition of the extracts was monitored over the course of the extraction as well. The cumulative yields of CWO from cedarwood chips using 80 L of carbon dioxide varied very little treatment to treatment, with all temperature/pressure combinations yielding between 3.55 and 3.88% CWO, and the cumulative yields were statistically equivalent. The rate of extraction was highest under the supercritical extraction conditions (i.e., 100 degrees C and 6000 psi). Under the liquid CO(2) conditions (i.e., 25 degrees C), the extraction rates did not vary significantly with extraction pressure. However, there were differences in the chemical composition of the collected CWO. Extractions at 100 degrees C gave a much lower ratio of cedrol/cedrene than extractions at 25 degrees C. The highest ratio of cedrol/cedrene was obtained using 25 degrees C and 1500 psi. The use of subcritical water was also investigated for the extraction of CWO as well. Although some CWO was extracted using this method, the temperature/pressure combinations that gave the highest weight percentage yields also gave oils with an off odor while those combinations that gave a higher quality oil had very low yields. It appears that the high temperatures and acidic conditions cause a dehydration of the tertiary alcohol, cedrol, to its hydrocarbon analogue, cedrene, during CO(2) or pressurized water extractions of cedarwood.     

Beta-carotene isomer composition of sub- and supercritical carbon dioxide extracts. Antioxidant activity measurement

In the present work sub- and supercritical extraction conditions using carbon dioxide were studied in order to obtain extracts with different compositions from the green microalgae Dunaliella salina. Different compositions of beta-carotene isomers were identified in the extracts by using HPLC-DAD. Also, antioxidant activity of the extracts was measured using a TEAC assay. An experimental design was applied considering two factors, extraction pressure and temperature, in a wide range of values, trying to maximize the extraction yield. Higher yields were obtained at high pressures and low temperatures, that is, at higher CO2 densities. Attempts were made to correlate the antioxidant activity of the extracts with their chemical composition by means of principal component analysis. A certain relationship was found between their antioxidant activity and the isomeric composition of beta-carotenes. As a result, an original equation is proposed to predict the antioxidant activity of extracts from D. salina in terms of the ratio 9-cis-beta-carotene/all-trans-beta-carotene, the concentration of alpha-carotene, and, especially, the concentration of 9-cis-beta-carotene.     

Comparison of yield, composition, and antioxidant activity of turmeric (Curcuma longa L.) extracts obtained using various techniques

Turmeric extracts were obtained from two lots of raw material (M and S) using various techniques: hydrodistillation, low pressure solvent extraction, Soxhlet, and supercritical extraction using carbon dioxide and cosolvents. The solvents and cosolvents tested were ethanol, isopropyl alcohol, and their mixture in equal proportions. The composition of the extracts was determined by gas chromatography-flame ionization detection (GC-FID) and UV. The largest yield (27%, weight) was obtained in the Soxhlet extraction (turmeric (S), ethanol = 1:100); the lowest yield was detected in the hydrodistillation process (2.1%). For the supercritical extraction, the best cosolvent was a mixture of ethanol and isopropyl alcohol. Sixty percent of the light fraction of the extracts consisted of ar-turmerone, (Z)-gamma-atlantone, and (E)-gamma-atlantone, except for the Soxhlet extracts (1:100, ethanol), for which only ar-turmeronol and (Z)-alpha-atlantone were detected. The maximum amount of curcuminoids (8.43%) was obtained using Soxhlet extraction (ethanol/isopropyl alcohol). The Soxhlet and low pressure extract exhibited the strongest antioxidant activities.     

不同提取方法对甘肃紫斑牡丹籽油品质的影响

为了对比冷榨法、溶剂浸出法、超临界CO₂萃取法3种提取方法所得紫斑牡丹籽油的品质,以甘肃紫斑牡丹籽为研究对象,从外观品质、出油率、理化特性及抗氧化能力方对3种方法提取的牡丹籽油品质进行观测。结果表明,采用溶剂浸提法提取的牡丹籽油得率最高,为27.27%;其次是超临界CO₂萃取法,为22.80%;冷榨法最低,为20.17%。采用超临界CO₂萃取法提取的牡丹籽油酸值和过氧化值低,抗氧化性能强,油品质量最高。采用冷榨法提取的牡丹籽油酸值低,品质较好,方法操作简单。3种提取方法各有特点,生产中可根据具体需求选择适用。     

Supercritical carbon dioxide extraction and fractionation of fennel oil

Ground fennel seeds were extracted with supercritical carbon dioxide. Small-scale subsequent extractions of the same sample showed that the composition of volatile compounds was changed with the extension of extraction time and only principal volatile components (limonene, fenchone, methylchavicol, and anethole) were present in the last-extracted sample. Fennel oil was successfully fractionated into the essential oil rich and fatty oil rich products in pilot-scale apparatus using two separators in series. Designed experiments were carried out to map the effects of pressure and temperature in the first separator on the yields and compositions of the products. The minimum level of the total undesired components in both essential oil rich and fatty oil rich products appeared at a pressure of 80-84 bar and a temperature of 31-35 degrees C in the first separator. Supercritical CO(2) extraction of fennel seeds resulted in higher yield (10.0%) than steam distillation (3.0%), almost the same yield as hexane extraction (10.6%), and lower yield than alcohol extraction (15.4%). Analysis of the volatile compounds revealed the significant difference of the composition in distilled oil and oleoresins prepared by CO(2) and solvent extractions. Sensory evaluation showed that the CO(2) extraction product and distilled oil were more intense in odor and taste than alcohol and hexane extracts.     

Supercritical fluid extraction of alkylamides from Echinacea angustifolia

Echinacea has been known for its immunostimulatory activity, and its alkylamide components have been linked to such biological activity. Consequently, alkylamides in Echinacea angustifolia were extracted using supercritical carbon dioxide from fresh and dried roots at 45-60 degrees C and 34-55 MPa, and the alkylamide yield in the extracts was determined. The yield of alkylamides from fresh roots increased with temperature yet decreased with pressure, whereas the yield from air-dried roots (moisture content 8.4%) increased with both temperature and pressure. Freeze-drying of the roots to a moisture content of 4.9% did not result in any further increase in the yield compared to that of air-dried roots. Alkylamide yield of the ground dried roots extract was the highest (p < or = 0.05) among those from fresh, ground and unground E. angustifolia roots. Supercritical fluid extraction therefore shows potential for the recovery of alkylamides from dried Echinacea roots.     

Paprika (Capsicum annuum) oleoresin extraction with supercritical carbon dioxide.

Paprika oleoresin was fractionated by extraction with supercritical carbon dioxide (SCF-CO(2)). Higher extraction volumes, increasing extraction pressures, and similarly, the use of cosolvents such as 1% ethanol or acetone resulted in higher pigment yields. Within the 2000-7000 psi range, total oleoresin yield always approached 100%. Pigments isolated at lower pressures consisted almost exclusively of beta-carotene, while pigments obtained at higher pressures contained a greater proportion of red carotenoids (capsorubin, capsanthin, zeaxanthin, beta-cryptoxanthin) and small amounts of beta-carotene. The varying solubility of oil and pigments in SCF-CO(2) was optimized to obtain enriched and concentrated oleoresins through a two-stage extraction at 2000 and 6000 psi. This technique removes the paprika oil and beta-carotene during the first extraction step, allowing for second-stage oleoresin extracts with a high pigment concentration (200% relative to the reference) and a red:yellow pigment ratio of 1.8 (as compared to 1.3 in the reference).     

Antioxidant activity of extracts of black sesame seed (Sesamum indicum L.) by supercritical carbon dioxide extraction

Antioxidant activities of extracts derived from sesame seed by supercritical carbon dioxide (SC-CO(2)) extraction and by n-hexane were determined using alpha,alpha-diphenyl-beta-picylhydrazyl (DPPH) radical scavenging and linoleic acid system methods. The highest extracted yield was given at 35 degrees C, 40 MPa, and a CO(2) flow rate of 2.5 mL min(-1) by an orthogonal experiment. The yields of extracts increased with increasing pressure, and yields at 40 and 30 MPa were higher than that by solvent extraction at 46.50%. Results from the linoleic acid system showed that the antioxidant activity follows the order: extract at 35 degrees C, 20 MPa > BHT > extract at 55 degrees C, 40 MPa > extract at 55 degrees C, 30 MPa > Trolox > solvent extraction > alpha-tocopherol. The SC-CO(2) extracts exhibited significantly higher antioxidant activities comparable to that by n-hexane extraction. The extracts at 30 MPa presented the highest antioxidant activities assessed in the DPPH method. At 20 MPa, the EC(50) increased with temperature, which indicated that the antioxidant activity was decreased in a temperature-dependent manner. The significant differences of antioxidant activities were found between the extracts by SC-CO(2) extraction and n-hexane. However, no significant differences were exhibited among the extracts by SC-CO(2) extraction. The vitamin E concentrations were also significantly higher in SC-CO(2) extracts than in n-hexane extracts, and its concentrations in extracts corresponded with the antioxidant activity of extracts.     

Extraction of chili,black pepper,and ginger with near-critical CO2, propane,and dimethyl ether: analysis of the extracts by quantitative nuclear magnetic resonance

Ginger, black pepper, and chili powder were extracted using near-critical carbon dioxide, propane, and dimethyl ether on a laboratory scale to determine the overall yield and extraction efficiency for selected pungent components. The temperature dependency of extraction yield and efficiency was also determined for black pepper and chili using propane and dimethyl ether. The pungency of the extracts was determined by using an NMR technique developed for this work. The volatiles contents of ginger and black pepper extracts were also determined. Extraction of all spice types was carried out with acetone to compare overall yields. Subcritical dimethyl ether was as effective at extracting the pungent principles from the spices as supercritical carbon dioxide, although a substantial amount of water was also extracted. Subcritical propane was the least effective solvent. All solvents quantitatively extracted the gingerols from ginger. The yields of capsaicins obtained by supercritical CO(2) and dimethyl ether were similar and approximately double that extracted by propane. The yield of piperines obtained by propane extraction of black pepper was low at approximately 10% of that achieved with dimethyl ether and CO(2), but improved with increasing extraction temperature.     

Supercritical carbon dioxide extraction and characterization of Laurus nobilis essential oil

Supercritical carbon dioxide extraction allowed essential oil of Laurus nobilis to be obtained. Extraction conditions were as follows: pressure, 90 bar; temperature, 50 degrees C; and carbon dioxide flow, Phi = 1.0 kg/h. Waxes were entrapped in the first separator set at 90 bar and -10 degrees C. The oil was recovered in the second separator working at 15 bar and 10 degrees C. The main components were 1,8-cineole (22.8%), linalool (12.5%), alpha-terpinyl acetate (11.4%), and methyleugenol (8.1%). Comparison with the hydrodistilled oil did not reveal any significant difference. Collection of samples at different extraction times during supercritical extraction allowed the change of the oil composition to be monitored. Lighter compounds such as hydrocarbon and oxygenated monoterpenes were extracted in shorter times than the heavier hydrocarbon and oxygenated sesquiterpenes.     

Effects of supercritical carbon dioxide (SC-CO(2)) oil extraction on the cell wall composition of almond fruits.

Extraction of oil from almond fruits using supercritical carbon dioxide (SC-CO(2)) was carried out at 50 degrees C and 330 bar on three sets of almonds: raw almond seeds, raw almond kernels, and toasted almond seeds. Three different oil extraction percentages were applied on each set ranging from approximately 15 to 16%, from approximately 27 to 33%, and from approximately 49 to 64%. Although no major changes were detected in the fatty acid composition between fresh and partially defatted samples, carbohydrate analysis of partially defatted materials revealed important changes in cell wall polysaccharides from almond tissues. Thus, at low extraction percentages (up to approximately 33%), pectic polysaccharides and hemicellulosic xyloglucans were the main type of polymers affected, suggesting the modification of the cell wall matrix, although without breakage of the walls. Then, as supercritical fluid extraction (SCFE) continues and higher extraction rates are achieved (up to approximately 64%), a major disruption of the cell wall occurred as indicated by the losses of all major types of cell wall polysaccharides, including cellulose. These results suggest that, under the conditions used for oil extraction using SC-CO(2), fatty acid chains are able to exit the cells through nonbroken walls; the modification of the pectin-hemicellulose network might have increased the porosity of the wall. However, as high pressure is being applied, there is a progressive breakage of the cell walls allowing the free transfer of the fatty acid chains from inside the cells. These findings might contribute to providing the basis for the optimization of SCFE procedures based on plant food sources.     

Phenolic and triterpenoid antioxidants from Origanum majorana L. herb and extracts obtained with different solvents

Antioxidant properties of marjoram (Origanum majorana L.) herb and extracts obtained with ethanol, n-hexane, and supercritical CO2 extraction are presented. Individual antioxidants, ursolic acid, carnosic acid, and carnosol, were quantified with high-performance liquid chromatography. The effects of different parameters (temperature and pressure) of high-pressure extraction on the yield of carnosol were studied. Furthermore, two marjoram herbs from Hungary and Egypt were compared measuring hydrogen-donating abilities with 1,1-diphenyl-2-picrylhydrazyl by spectrophotometric and the total scavenger capacities by chemiluminometric methods from the aqueous extracts of the herbs. The antioxidant activities of the solvent extracts were performed using the Rancimat method. The Egyptian herb and its extracts possessed better antioxidant activities than Hungarian ones. Applying supercritical CO2 extraction, the highest value of carnosol was obtained at 400 bar and 60 degrees C.     

Influence of drying methods and agronomic variables on the chemical composition of mate tea leaves (Ilex paraguariensis A. St.-Hil) obtained from high-pressure CO2 extraction

The main objective of this work is to assess the influence of two drying methods (microwave and vacuum oven) and some agronomic variables (plant fertilization conditions and sunlight intensity) on the characteristics of mate tea (Ilex paraguariensis) leaves extracts obtained from high-pressure carbon dioxide extractions performed in the temperature range from 20 to 40 degrees C and from 100 to 250 bar. Samples of mate were collected in an experiment conducted under agronomic control at Ervateira Bar?o LTDA, Brazil. Chemical distribution of the extracts was evaluated by gas chromatography coupled with a mass spectrometer detector (GC/MS). In addition to extraction variables, results showed that both sample drying methods and agronomic conditions exert a pronounced influence on the extraction yield and on the chemical distribution of the extracts.     

Yield and composition of grape seed oils extracted by supercritical carbon dioxide and petroleum ether: varietal effects

Grape seed has a well-known potential for production of oil as a byproduct of winemaking and is currently produced as a specialty oil byproduct of wine manufacture. Seed oils from eight varieties of grapes crushed for wine production in British Columbia were extracted by supercritical carbon dioxide (SCE) and petroleum ether (PE). Oil yields by SCE ranged from 5.85 +/- 0.33 to 13.6 +/- 0.46% (w/w), whereas PE yields ranged from 6.64 +/- 0.16 to 11.17 +/- 0.05% (+/- is standard deviation). The oils contained alpha-, beta-, and gamma-tocopherols and alpha- and gamma-tocotrienols, with gamma-tocotrienol being most important quantitatively. In both SCE- and PE-extracted oils, phytosterols were a prominent feature of the unsaponifiable fraction, with beta-sitosterol quantitatively most important with both extractants. Total phytosterol extraction was higher with SCE than with PE in seven of eight variety extractions. Fatty acid composition of oils from all varieties tested, and from both extraction methods, indicated linoleic acid as the major component ranging from 67.56 to 73.23% of the fatty acids present, in agreement with literature reports.     

Comparison among soil Series and extraction methods for the analysis of trifluralin

Accurate analytical procedures are needed to improve understanding of the fate and transport of trifluralin, a chemical widely used as a herbicide. Analytical determination of trifluralin is challenging due to its hydrophobic, yet volatile, character and its tendency to degrade into numerous metabolites. In this research, efficient analytical methods for fortified and field-incurred soils were developed for simultaneous quantitation of trifluralin, I [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine, CAS Registry No. 1582-09-8; CAS Registry No. have been provided by the author], a trifluralin metabolite, II [2,6-dinitro-N-propyl-4-(trifluoromethyl)benzenamine, CAS Registry No. 2077-99-8], and a related trifluoromethyldinitroaniline isomer of trifluralin, III [2,4-dinitro-N,N-dipropyl-6-(trifluoromethyl)benzenamine, CAS Registry No. 23106-20-9]. Extractions of trifluralin (0.5 and 2.5 microg/g) from silt loam, sandy loam, and silty clay soils were compared. A method was developed for the supercritical fluid extraction of trifluralin from soil using modified supercritical carbon dioxide, and the effects of cosolvent, pressure, and flow rate on recovery were evaluated. Supercritical fluid extraction was compared to liquid vortex extraction and automated Soxhlet (soxtec) extraction. Solid-phase extraction was examined for purifying soil extracts. Protocols were developed for analysis of extracts by gas and/or liquid chromatography. Immunoassay was investigated but proven to be impractical for this analysis. Soil properties and extraction methods were observed to affect the level of coextracted background interferences. Trifluralin exhibited concentration-dependent recovery regardless of soil series or extraction method.     

Extraction of natural complex phenols and tannins from grape seeds by using supercritical mixtures of carbon dioxide and alcohol

Proanthocyanidins are supposed to have some therapeutical properties as antioxidants and antineoplasics. Most of the proanthocyanidins, however, are not commercialized since their separation from natural sources is either very expensive or not well-known. In this work, the feasibility of application of mixtures of carbon dioxide and alcohol under supercritical conditions for selective extraction of some phenolic compounds from grape seeds has been studied, among them some low polymerized proanthocyanidins, their main monomer units, (+)-catechin and (-)-epicatechin, and some low molecular weight phenolic compounds, like gallic acid. An analytical-scale supercritical fluid extractor, whose operation was previously optimized, was used to carry out the experiments. A commercial concentrate of complex phenols and tannins from grape seeds was subjected to supercritical extraction in order to find the best operation conditions before directly extracting defatted milled grape seeds. The solvent capacity was found to increase with pressure and with the amount of alcohol used as cosolvent as expected. Such variation in solvent capacity could be used for design of a selective separation process where individual phenolic compounds or groups of them could be obtained. HPLC coupled with two types of detectors, diode array and mass spectrometry, was used for tentative identification and quantification of complex phenols and tannins in the extracts and in the raw materials used for extraction.     

Supercritical carbon dioxide extraction of oil and squalene from amaranthus grain

Supercritical carbon dioxide (SC CO(2)) was used for the extraction of oil and squalene from Amaranthus grain. Very small amounts of oil could be extracted by SC CO(2) from undisrupted grains, although SC CO(2) possesses higher diffusivity. Grinding increased the extraction rate and oil yield, and smaller particle size gave higher extraction rate. The oil yield and initial extraction rate increased linearly with the increasing SC CO(2) flow rate from 1 to 2 L/min. Increasing the flow rate of SC CO(2) above 2 L/min resulted in only a slight increase of oil yield and extraction rate. In the pressure range of 150-250 bar, extraction decreased with increasing temperature at a constant pressure, whereas at a pressure of 300 bar, the extraction yield increased with increasing temperature. Possible reasons for this are discussed. Effects of temperature and pressure on squalene yield were different from those on oil yield. A good oil yield (4.77 g of oil/100 g of grain) was obtained at 40 degrees C and 250 bar. The highest squalene yield (0.31 g of squalene/100 g of grain) and concentration (15.3% in extract) were obtained at 50 degrees C and 200 bar, although the oil yield under this condition was low (2.07 g of oil/100 g of grain). The moisture content within 0-10% had little influence on yields of oil and squalene at 40 degrees C and 250 bar. Finally, the oil yield and the squalene concentration in the extracts by SC CO(2) were compared to those by solvent extraction.