Liquid CO2 Extraction Research Articles

Liquid and supercritical CO2 extraction of fat from rendered materials

The separation of fat from rendered materials has potential for value-added products, fuels and feed sources for animals. Current industrial processes utilize continuous screw pressing to extract fat from rendered materials, but the ability to minimize residual fat content is limited. In this work, liquid and supercritical CO2 were used to extract the remaining fat from rendered poultry meal. CO2 extraction offers high extraction yields with potential ecological and economic benefits for the rendering industry. A semi-batch extraction unit was used to investigate the effect of pressure (69–345bar), temperature (25°C, 40°C and 50°C), flow rate, and mass of CO2 on the extraction yield and the fat solubility. Maximum extraction yields between 87% and 97% were obtained which produced a remaining fat content of 1.0±0.3wt% in the extracted poultry meal. Fat solubility increased with pressure but decreased with temperature, providing liquid CO2 with the highest fat solubility (6.47g/L) at 25°C and 345bar. The Chrastil model successfully correlated the solubility data as a function of density and temperature, obtaining an AARD value of 5.56%. Gas chromatography was used to analyze the composition of fatty acids, obtaining similar results with those reported in the literature. It can be concluded that high fat extraction yields can be obtained using CO2 and that liquid CO2 is more effective than supercritical CO2 for the extraction of rendered fats under the conditions tested.

Effects of Different Extraction Methods and Conditions on the Phenolic Composition of Mate Tea Extracts

A simple and rapid HPLC method for determination of chlorogenic acid (5-O-caffeoylquinic acid) in mate tea extracts was developed and validated. The chromatography used isocratic elution with a mobile phase of aqueous 1.5% acetic acid-methanol (85:15, v/v). The flow rate was 0.8 mL/min and detection by UV at 325 nm. The method showed good selectivity, accuracy, repeatability and robustness, with detection limit of 0.26 mg/L and recovery of 97.76%. The developed method was applied for the determination of chlorogenic acid in mate tea extracts obtained by ethanol extraction and liquid carbon dioxide extraction with ethanol as co-solvent. Different ethanol concentrations were used (40, 50 and 60%, v/v) and liquid CO2 extraction was performed at different pressures (50 and 100 bar) and constant temperature (27 ± 1 °C). Significant influence of extraction methods, conditions and solvent polarity on chlorogenic acid content, antioxidant activity and total phenolic and flavonoid content of mate tea extracts was established. The most efficient extraction solvent was liquid CO2 with aqueous ethanol (40%) as co-solvent using an extraction pressure of 100 bar.

Purification of 2‐Monoacylglycerols Using Liquid CO2 Extraction

AbstractThe fatty acid moiety of 2‐monoacyl‐sn‐glycerol (2‐MAG) undergoes spontaneous acyl migration to the sn‐1(3) position, resulting in a thermodynamic equilibrium of approximately 1:9 of 2‐MAG to 1(3)‐monoacyl‐sn‐glycerol (1‐MAG). Spontaneous acyl migration is an impediment to synthesizing and isolating specific 2‐MAG for use as intermediates in the synthesis of structured triacylglycerols. 2‐Monooleoyl‐sn‐glycerol was synthesized by the enzymatic ethanolysis of triolein and isolated by liquid CO2 extraction. The resultant MAG, diacylglycerol, and fatty acid ethyl esters were quantified by 1H NMR and supercritical fluid chromatography. The low polarity of the CO2 and mild extraction temperature (25 °C) resulted in very low spontaneous acyl migration rates, allowing the MAG to be isolated in 80% yield and in a very high 2‐MAG:1‐MAG ratios of ≥93 mol%.

Liquid CO2 Extraction of Jasminum grandiflorum and Comparison with Conventional Processes

The concrete (0.35%) of Jasminum grandiflorum L. flowers was prepared by extraction in n-pentane, and the absolute (0.27%) by fractionation of the n-pentane extract (concrete) with cold methanol. Direct extraction of flowers with liquid CO2 gave a relatively fat-free product in 0.26% yield. The liquid CO2 extract was enriched with terpenoids and benzenoids, thus providing the organoleptically accepted product. The major compounds, such as benzyl acetate, (E,E)-alpha-farnesene and (Z)-3-hexenyl benzoate, along with compounds like indole, methyl anthranilate, (Z)-jasmone, (Z)-methyl jasmonoate and (Z)-methyl epi-jasmonoate, are responsible for the high diffusivity of the jasmine fragrance. These compounds have been obtained with improved recoveries in the liquid CO2 extract. On the other hand, the yield of the essential oil was poor (0.05%), and some polar compounds (oxygenated terpenoids) were recovered in less amounts in comparison with either the n-pentane or liquid CO2 extract.

LIQUID CO2 EXTRACTION OF FLOWERS OF PANDANUS FASCICULARIS LAM. AND FRACTIONATION OF FLORAL CONCRETE AND COMPARATIVE COMPOSITION OF THE EXTRACTS

Kewda (Pandanus fascicularis Lam.) is an important economic plant, and its male inflorescence is used in the production of kewda perfumes. It grows wild and is also cultivated; an estimated 35 million flowers (3,500 tons) worth $10 million are processed annually in Ganjam (19.18°N, 84.51°E) India. Kewda products are used in flavoring tobacco, foods and sweet meats, and in traditional medicines. Extraction of flowers with hexane furnishes the “concrete,” which, on fractionation with cold methanol, gives “absolute.” We have now fractionated the concrete with liquid CO2 to obtain fractions enriched with benzenoids and terpenoids. We have also carried out direct liquid CO2 extraction of flowers. It is notable that in liquid CO2 fractionation, a solvent-free product with improved organoleptic profile is obtained. The direct extraction of flowers with liquid CO2 afforded a superior product in 0.24% yield; however, the process is suitable for extraction in the laboratory only. PRACTICAL APPLICATIONS Kewda products are used in flavoring tobacco, foods and soft drinks. The essential oil obtained by hydrodistillation gave very low yield, where as hexane extract (concrete) yielded nearly 10 times more in comparison to essential oil. The concrete and absolute obtained by partial precipitation of wax may not be suitable for use in foods because of the presence of organic solvent residues. The liquid CO2 fractionation of concrete, however, affords absolute with similar composition but free from solvent residues, and is recommended for using in foods. Further liquid CO2 fraction of concrete is organoleptically superior compared with absolute obtained in the conventional way. Similarly, extraction of flowers in liquid CO2 gave higher yield of valuable components with less percentage of waxy materials. Because bulk density of flowers is low, large liquid CO2 plant is required for commercial scale production, making CO2 fractionation of concrete an attractive alternative process.

Liquid CO2 extraction of flowers and fractionation of floral concrete of Michelia champaca Linn

Extraction of the fresh flowers of Michelia champaca L. with liquid CO2 provided a floral extract in 1.0±0.04wt% yields. The extract so obtained contains far less waxes and is organoleptically very superior. Similarly extraction with pentane gave the so-called ‘Concrete’ in 1.58±0.06wt%. While the concrete contains co-extracted floral waxes that make it unsuitable for blending with other perfumes, direct extraction with CO2 is an expensive process mainly due to low bulk density of flowers and their availability during short flowering season. On the other hand, fractionation of the concrete with liquid CO2 to separate the waxy components has provided solvent and almost wax free fractions. The duration of extractive fractionation has been optimized for selective extraction with liquid CO2 at 62bar. These liquid CO2 fractions of concrete and liquid CO2 extract of flowers were analyzed by GC and GC/MS and their composition compared with that of concrete and partially de-waxed absolute obtained in the conventional way. The major fragrance compounds enriched in the direct liquid CO2 extract were methyl benzoate (11.5±0.8%), phenyl ethyl alcohol (5.0±0.6%), phenyl acetonitrile (10.4±1.1%), indole (1.2±0.3%), methyl anthranilate (1.3±0.5%), E-β-ionone (1.5±0.4%), and Z-methyl jasmonoate (1.0±0.3%). The liquid CO2 fractionation of concrete is a practical process and the first fraction is comparable with direct liquid CO2 flower extract in terms of composition of the major compounds.

Composition of Absolutes of Jasminum sambac L. Flowers Fractionated with Liquid CO2 and Methanol and Comparison with Liquid CO2 Extract

Absolutes obtained by fractionation of the pentane extract (concrete) of flowers of Jasminum sambac L. with cold methanol or liquid CO2 were compared. Direct extraction of flowers with liquid CO2 gave a relatively fat-free and superior product in 0.44% yield. It was found that the CO2 method of fractionation of pentane extract is a practical process providing an organoleptically superior product, though the product is not totally free from waxy substances. (E,E)-α-Farnesene and (Z)-3-hexenyl benzoate, along with compounds like indole, methyl anthranilate and methyl jasmonate, responsible for high diffusivity of the jasmine fragrance, have been obtained with improved recoveries in the CO2 fractionated concrete.

Synthesis and Phase Behavior of CO2-Soluble Hydrocarbon Copolymer: Poly(vinyl acetate-alt-dibutyl maleate)

We report the synthesis of a new hydrocarbon copolymer which is soluble in supercritical carbon dioxide. Poly(vinyl acetate-alt-dibutyl maleate) (PVAc-alt-PDBM) copolymer was synthesized by free-radical polymerization mediated by the RAFT technique. Liquid CO2 extraction was performed to remove the residual monomer and solvent from the final product. The solubility of the copolymers was measured in a variable volume view cell at temperatures between 25 and 75 °C. The phase behavior of the copolymer in CO2 was studied in terms of its molecular weight and concentration in the solvent. It was found that the copolymer shows good solubility in CO2 approaching that of perfluoropolyether (PFPE) and poly(dimethylsiloxane) monomethacrylate (PDMS-mMA).

Alumina aerogels prepared via rapid supercritical extraction

Alumina aerogels with surface areas from 460 to 840 m2/g and bulk densities from 0.025 to 0.079 g/cm3 were successfully fabricated using variations of an aluminum isopropoxide-based recipe developed by Armor and Carlson and the rapid supercritical extraction (RSCE) process developed at Union College. By utilizing the Union College RSCE method, it is possible to convert an alumina aerogel precursor mixture into aerogel monoliths in as little as 7.5 h. This process is safer than methanol extraction in an autoclave and faster and simpler than liquid CO2 solvent exchange and extraction. By increasing the concentration of aqueous HNO3 used in the precursor mixture, we were able to fabricate aerogels with significantly increased surface area, decreased bulk density, and altered microstructure. We attribute the observed variation in these aerogel properties at a given HNO3 concentration to environmental factors such as humidity. The ability to more easily fabricate alumina aerogels with desirable properties will assist in making them a viable option for catalytic and other applications.

Selective Liquid CO2 Extraction of Purine Alkaloids in Different Ilex paraguariensis Progenies Grown under Environmental Influences

In this investigation, liquid carbon dioxide at 20 degrees C and 150 bar was used for the selective extraction of caffeine and theobromine from dry leaves of mate. A comparison between the chromatograms from CO2 extraction and traditional solvent extraction supports the selectivity of carbon dioxide for these purine alkaloids. The advantages of selective liquid CO2 extraction in terms of speed and resolution of UV/HPLC is also evidenced. A randomized block design of experiments was proposed to investigate the influence of 16 progenies of Ilex paraguariensis grown in 3 diverse sites on the contents of caffeine and theobromine in liquors of mate leaves obtained by extraction with compressed CO2. A significant effect of both these factors on the parameters investigated was observed by involving the F distribution in the statistical analysis. A cluster analysis based on the experimental uncertainties in the contents of these two methylxanthines has identified from four to six different groups of mate progenies.

Green chemical processing in the teaching laboratory: a convenient liquid CO2 extraction of natural productsElectronic supplementary information (ESI) available: experimental procedure (including instructors? notes, student handout, and demonstration procedure) and movie clip of extraction process. See http://www.rsc.org/suppdata/gc/b4/b405810k/

A unique liquid CO2 extraction laboratory developed for a greener organic teaching lab curriculum provides an effective, inexpensive, and convenient procedure for teaching natural products extraction concepts and techniques using modern green extraction technology. The procedure is appropriate for the teaching lab, does not require any special equipment, and allows the students to see the phase change and extraction as they occur. Students learn extraction and spectroscopic analysis skills, are exposed to a dramatic visual example of phase change, and are introduced to commercially successful green chemical processing with CO2.

Carbon dioxide extraction of residual chloroform from biodegradable polymers.

Biodegradable polymeric devices for drug delivery and tissue engineering are often fabricated with the use of organic solvents and may still contain significant amounts of solvent (> 1 wt%) even after aggressive vacuum drying. This excess solvent can interfere with tissue response and the mechanical properties of the devices. The aim of this article is to demonstrate that liquid CO(2) extraction can be used to reduce residual solvent in dense poly(L-lactide-co-glycolide) devices to 50 ppm relatively quickly and with minimal changes in architecture under some conditions. Two liquid CO(2) extraction systems were developed to examine the removal of residual solvents from bar-shaped PLGA devices: (1) a low-pressure (1400 psi) batch system, and (2) a high-pressure (5000 psi) continuous-flow system. Eight hours of extraction in the high-pressure system reduced residual chloroform in 3 mm thick bars below the 50-ppm target. A simple Fickian diffusion model was fit to the extraction results. Diffusion coefficients ranged from 1.10 x 10(-6) cm(2)/s to 2.64 x 10(-6) cm(2)/s. The model predicts that approximately 1 h is needed to dry 1-mm bars to chloroform levels below 50 ppm, and 7 h are needed for 3 mm thick bars. The micro- and macroarchitectures of porous PLGA scaffolds created by particulate leaching were not significantly altered by CO(2) drying if the salt used to make the pores was not removed before drying.

YIELD AND QUALITY OF ONION FLAVOR OIL OBTAINED BY SUPERCRITICAL FLUID EXTRACTION AND OTHER METHODS

ABSTRACTMethods of extraction of onion flavor oil were studied including supercritical fluid extraction using carbon dioxide (CO2), liquid CO2 extraction and steam distillation‐solvent extraction. The effect of using entrainers with supercritical fluid extraction was also studied. The yield and the quality of onion extracts obtained from the different methods were compared. The maximum yield of 0.0324% was obtained by supercritical CO2 extraction at 3600psi (24.5 MPa), 37C at a CO2 flow rate of 0.5 L/min. Ethyl alcohol used as entrainer enhanced the yield of onion oil over that obtained by supercritical CO2 experiment without entrainer at the CO2flow rate of 1.0 L/min. Gas chromatography and combined gas chromatography‐mass spectrometry of the extracts indicated that the flavor profiles were different for extracts obtained by different methods. Supercritical and liquid CO2 extracts had fresh onion‐like flavor as opposed to a cooked flavor of the extract obtained by steam distillation‐solvent extraction.

Western Australian Sandalwood Oil: Extraction by Different Techniques and Variations of the Major Components in Different Sections of a Single Tree

Steam distillation, solvent extraction, supercritical fluid extraction (SCCO2) and liquid CO2 extraction were used to obtain the volatile oil from Western Australian Sandalwood (Santalum spicatum (R. Br.) A. DC.). Supercritical fluid extraction afforded the highest yields of extractable material and total volatiles. The percentages of five sesquiterpene alcohols, epi-α-bisabolol (1), (Z)-α-santalol (2), 2(E), 6(E)-farnesol (3), (Z)-β-santalol (4) and (Z)-nuciferol (5), were highest in the steam distillate. The variations in the relative amounts of these sesquiterpenes in the essential oil recovered by SCCO2 extraction of different sections of a single tree have been investigated. © 1997 by John Wiley & Sons, Ltd.

Flavor Constituents of Aqueous Fraction Extracted from Comte Cheese by Liquid Carbon Dioxide

ABSTRACTIsolation, purification and identification of some low‐molecular‐weight compounds from a water‐soluble extract of Comté cheese was achieved. We used liquid CO2 extraction, subsequent fractionation (by gel permeation and reserve‐phase HPLC) and mass spectometry. Major constituents were N‐acyl amino acids (N‐acetyl methionine, N‐propionyl methionine, N‐propionyl leucine, N‐propionyl phenylalanine), dike‐topiperazines (cyclo(Pro‐Pro), cyclo(Pro‐Val), cyclo(Pro‐Phe), cy clo(Pro‐Leu), cyclo(Pro‐Ala)) and non‐peptide compounds (theo‐bromine, 4‐methyl‐t‐thiazoleethanol, uracil, (5–6)dihydro‐uracil, thymine). These compounds were synthesized and tasted. Most were bitter. N‐propionyl methionine had a cheese flavor but was not detected when added to a simulated cheese at 180 mg/L.

Volatile compounds and odor characteristics of carbon dioxide extracts of coriander (Coriandrum sativum L.) fruits

Volatile components of coriander fruits were isolated by supercritical carbon dioxide (SC-CO2) extraction at 9 MPa/40 degrees C and analyzed using GC-MS. The composition of SC-CO2 extract was compared with liquid CO2 (LCO2) extract (5.4 MPa/25 degrees C). The SC-CO2 extract resembled the conventional isolates in the relative amounts of monoterpene hydrocarbons. The oxygenated monoterpenes comprised 80 % of the SC-CO2 and 82% of the LCO2 extract, linalool being the main compound (67%) in both extracts. The sensory characteristics of the aroma of CO2 extracts were evaluated and compared with those of freshly ground spice. No major differences in the average intensities of any odor attribute could be found between the coriander fruits harvested in 1990 and 1991. The SC-CO2 extract was evaluated to be more terpenous and less sweet than the reference (coriander 1990). The assessors described the supercritical extract as the most terpenic and spiciest with some pungency. The aroma of LCO2 extract was characterized as distinctly pomerancelike and sweet, although all odor attributes were evaluated to be less intense than those in freshly ground coriander fruits.

Modeling of Liquid CO2 Extraction of Peanut Oil in a Fixed Bed

ABSTRACT BATCH extraction of peanut oil with liquid carbon dioxide in a fixed bed is described with several models. Equations to describe oil extraction kinetics are presented. In addition to being dependent on temperature and pressure, the extraction rate curves are shown to be dependent on oilseed particle size. The oil concentration gradient in the bed is fitted to a solid/liquid chromatographic column model. The minimum length of bed needed to keep a continuous system operating at its optimum rate is estimated by the method of a breakthrough curve.

In situ capacitance studies of thin polymer films during compressed fluid extraction

Supercritical and compressed liquid CO2 extraction of thin solid organic films was studied using in situ capacitance monitoring. Parallel plate and fringe field capacitors were fabricated using organic films as principal dielectric media. Supercritical and compressed liquid CO2 extraction of these films at 100 bar and 30–45°C caused compositional and physical changes in the host polymer matrix that were correlated to capacitance history. As a result of these studies, film damage during extraction was attributed to explosive decompression of the CO2 solvent. In addition, a mechanism for supercritical fluid extraction of nonvolatile solutes from thin films, which is consistent with these capacitance measurements, is discussed.

Characterization of volatile compounds in linden blossoms Tiolia cordata mill

Abstract80 Compounds were identified in the Likens‐Nickerson extracts of linden blossoms harvested near Buis‐les‐Baronnies (Drǒme, France). The composition of the essential oils extracted from the flowers and the bracts differs considerably. The essential oil derived from the flowers is characterized by a high percentage of monoterpenes (53%), and by a much lower percentage of aldehydes (12%). Whereas, oil extracted from the bracts is richer in aldehydes (25%) than in monoterpene hydrocarbons (2.0–4.5%), it also contains a reasonable proportion of aliphatic hydrocarbons (3.0–5.0%). From a ‚liquid CO2 extract’︁ of the flowers, 14 different compounds were identified whose principal component was dibutyl phthalate (11.8%), whereas the monoterpenoids as a whole represent only 14.0% of the total extract.

New Cembranoids from Burley Tobacco

Abstract The liquid CO2-extract of aged burley tobacco was investigated for its content of diterpenoids, which are considered as important precursors of flavour constituents. Among several cembranoids, already known from various tobacco types, 4,8-dimethyl-8-hydroxy-11-(1-methyl-ethyl)-14-oxo-pentadeca-5,9-diene-4-olide, a new natural product, could be identified, evidently originating from 2,6,11-cembratriene-4,8-diol by oxidative cleavage of the 11,12-double bond with subsequent cyclization to the seco-lactone 14.