Characterization of wheat bran oil obtained by supercritical carbon dioxide and hexane extraction

Supercritical carbon dioxide (SC-CO₂) and soxhlet extraction using was carried out to extract oil from wheat bran oil. For SC-CO₂, the pressure and temperature were ranging from 10 to 30 MPa and 313.15–333.15 K. The extraction was performed in a semi batch process with a CO₂ flow rate of 26.81 g/min for 2 h. Wheat bran oil was characterized to investigate the quality. Acid value (AV) and peroxide value (POV) were higher in hexane extracted oil compared to SC-CO₂ extracted oil. Induction period was measured by rancimat test. The oil obtained by SC-CO₂ extraction had higher capability to delay the oxidation by surrounding environment. The DPPH radical scavenging activity was also measured. The SC-CO₂ extracted oil showed higher radical scavenging activity compared to hexane extracted oil.     

Argon as a potential processing media for natural and synthetic substances

Phase equilibrium data of caffeine, vanillin, o-ethyl vanillin and a natural rosemary extract (containing 73.9% carnosic acid and 14.7% carnosol) in argon have been determined in present work.Solubility data were determined at temperatures of 313.15 K, 333.15 K and 363.15 K and in the pressure range from 0.82 MPa up to 50.27 MPa using a static–analytic method and were compared to solubility data of the same substances in CO₂.Maximal solubility of vanillin in argon was obtained at a temperature of 313.15 K and a pressure of 43.8 MPa, approx. 0.015 g/g. Comparing the solubility data of pure vanillin in argon and in CO₂ higher solubility in argon is observed at lower temperatures and pressures. For o-ethyl vanillin the solubility in argon is higher in comparison to solubility in CO₂ in the entire range of pressure, especially at higher temperatures_.Maximal solubility of caffeine in argon was observed at a temperature of 363.15 K 0.001361 g caffeine/g argon at 38.9 MPa. With increasing pressure solubility increases, while temperature does not have a noticeable impact in the temperature range from 313.15 K to 333.15 K; the solubility increased with increasing temperature to 363.15 K. Similarly, solubility of carnosic acid extract increases with increasing pressure, from about 0.0097 × 10⁻² g substance/g gas at 2.08 MPa and at 313.15 K to 0.0338 × 10⁻² g substance/g gas at 50.27 MPa and at 363.15 K.Solubility of the investigated compounds in argon is a function of both, pressure and temperature. Generally, pressure significantly impacts solubility particularly up to a pressure of 20.0 MPa in case of vanillin and up to 30 MPa in case of o-ethyl vanillin and carnosic acid extract. An additional increase of pressure has only a slight impact on solubility. In the case of caffeine, the impact of pressure on the solubility becomes more evident at pressures higher than 20 MPa.     

Response surface optimization of supercritical CO2 extraction of α-tocopherol from gel and skin of Aloe vera and almond leaves

Supercritical fluid extraction (SFE) was studied as an alternative technology in the pharmaceutical industry for the separation of α-tocopherol from gel and skin of Aloe vera and almond leaves. The influence of operating conditions was investigated on the recovery of supercritical carbon dioxide (SC-CO₂) extraction of α-tocopherol from three-year old Aloe vera (Aloe barbadensis Miller) leaf gel. The obtained results were compared with the conventional Soxhlet extraction. Response surface methodology (RSM) was applied to optimize effective variables on the extracted recovery of α-tocopherol. The maximum α-tocopherol recovery of 53.41% from Aloe vera gel was obtained with employing RSM predicted optimal operating conditions of 32 MPa, 45.91 °C, 0.84 ml SC-CO₂/min and 140 min for extraction. The α-tocopherol extraction yield for gel and skin of Aloe vera and almond leaves at these optimal operating conditions were obtained 1.53, 16.29 and 2.61 mg/100 g dry sample, respectively.     

Ethanol modified supercritical carbon dioxide extraction of flavonoids from Momordica charantia L. and its antioxidant activity

Ethanol modified supercritical carbon dioxide (SC-CO₂) extraction of flavonoids from Momordica charantia L. fruits and its antioxidant activity were performed. The influences of parameters such as temperature, extraction time and pressure on the yield of flavonoids were investigated. The antioxidant activities of flavonoids were assessed by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay and β-carotene bleaching test. The experimental data obtained indicated that pressure, temperature and time had significant effect on the extraction yield. The optimum extraction conditions, determined by the 3D response surface and contour plots derived from the mathematical models, were as follows: extraction temperature 46 °C, pressure 33.4 MPa, and extraction time 53.2 min. Under these conditions, the experimental value was 15.47 mg/g, which was well matched with value predicted by the model. The antioxidant activity of flavonoids obtained by ethanol modified SC-CO₂ extraction method had higher antioxidant activity than the flavonoids extracted by conventional solvent extraction (CSE) method. The DPPH radical-scavenging ability of flavonoids obtained by ethanol modified SC-CO₂ extraction method reached to 96.14 ± 1.02%, equivalent to the clearance rate of ascorbic acid at 1.2 mg/mL. Results indicated that ethanol modified SC-CO₂ extraction was a suitable approach for the selective extraction of flavonoids from M. charantia L.     

Supercritical carbon dioxide combined with high power ultrasound: An effective method for the pasteurization of coconut water

Industrially, thermal treatments are extensively used to inactivate microorganisms in foods. However, the demand for new pasteurization methods with reduced impact on the nutritional content and overall food quality is increasing. In this context, this study investigated and compared the effect of supercritical carbon dioxide (SC-CO₂) alone or in combination with high power ultrasound (HPU) on both the natural microbial flora (mesophilic, lactic acid bacteria and yeast and molds) of coconut water and the pathogenic Gram-negative bacteria Salmonella enterica inoculated in the product. Inactivation kinetics were obtained at 12 MPa, by means of batch apparatuses, at different times (from 1 up to 60 min) and temperature conditions (from 25 up to 45 °C). The synergistic effect of SC-CO₂ + HPU was evident and a higher microbial reduction was achieved compared to SC-CO₂ alone: at 12 MPa and 40 °C about 5 log reductions were achieved for natural microbial flora in about 15 min while about 30 min were needed for SC-CO₂ treatment. The storage study highlighted that SC-CO₂ treated coconut water resulted microbiologically unstable and showed heavy regrowth phenomena during the storage, while, a full shelf life of 4 weeks was assured for SC-CO₂ + HPU treated samples.     

Optimization of supercritical carbon dioxide removal of lipid and cholesterol from goat placenta using response surface methodology

Supercritical CO₂ (SC-CO₂) extraction was applied to remove lipid and cholesterol from freeze-dried goat placenta. A response surface methodology (RSM) was employed to optimize the extraction parameters. The effects of pressure, temperature, flow rate of CO₂ and extraction time on the yields of lipid and cholesterol were investigated. Response surface analysis showed that the data were adequately fitted to second-order polynomial model. The independent variables, quadratics of pressure and extraction time, and the interaction between pressure and temperature had significant effects on the yields of lipid and cholesterol, respectively. The optimum parameters within the experimental range of the variables were 34.6 MPa, 35.3 °C, 29.1 min with a CO₂ flow rate of 18.2 L/h. Under such condition, the yields of lipid and cholesterol were predicted to be 21.02% and 8.46 mg/g, respectively. Furthermore, the removal efficiency of cholesterol by SC-CO₂ was higher than those achieved by Soxhlet and Folch extraction methods.     

A bioactivity based comparison of Echinacea purpurea extracts obtained by various processes

Echinacea species is provided as dietary supplements for various infectious and immune related disorders and has a potential role in cancer prevention. The aim of this study was to optimize the extraction of total flavonoids using different extraction methods and investigate the cytotoxic effects on various cancer cell lines (CaCo-2, MCF-7, A549, U87MG, and HeLa) and VERO (African green monkey) as a non-cancerous cell line. Box-Behnken statistical design was used to evaluate the effect of pressure (100–200 bar), temperature (40–80 °C) and ethanol as co-solvent (6–20 wt%) at a flow rate of 15 g/min for 60 min in supercritical CO₂ extraction and the effect of temperature (60–100 °C), time (5–15 min) and power (300–900 W) in microwave-assisted extraction. Optimum extraction conditions were elicited as 300 bar, 80 °C and 13% co-solvent yielding 0.472 mg rutin equivalent total flavonoids/g extract in SC-CO₂ extraction, whereas 60 °C, 10 min and 300 W yielded the highest (0.202 mg rutin equivalent) total flavonoids in microwave-assisted extraction. Additional trials with subcritical water (0.022 mg/g) and Soxhlet extraction with methanol (0.238 mg/g) yielded lower flavonoid contents. The exposures upto 50 μg/ml of extracts revealed no significant inhibition on the proliferation of both tested cancer cells and healthy VERO cells.     

Synthesis,characterization and structure effects of polyethylene glycol bis(2-isopropoxyethyl) dimethyl diphosphates on lanthanides extraction with supercritical carbon dioxide

Three new CO₂-philic open-chain organophosphorous chelating ligands, i.e. ethylene glycol bis(2-isopropoxyethyl) dimethyl diphosphate (EG2IPE), triethylene glycol bis(2-isopropoxyethyl) dimethyl diphosphate (EG3IPE), and tetraethylene glycol bis(2-isopropoxyethyl) dimethyl diphosphate (EG4IPE), were synthesized and characterized. Solubilities of these ligands in scCO₂ were determined at different combinations of temperature (313.15⿿333.15 K) and pressure (9⿿20 MPa), which generally showed considerable solubility in each case. These experimental data are in agreement with computed data via a semi-empirical model, in which the average absolute relative deviations lie in the range of 4.09⿿4.95%. The effect of these ligands on supercritical fluid extraction of selected rare earth metals (La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Gd³⁺, Er³⁺, and Yb³⁺) was investigated at 313.15 K and 20 MPa. The extraction efficiency of this system was found to increase in the order EG4IPE < EG3IPE < EG2IPE with a range from 55% to 79%. The rationale behind different selectivities toward these metals was also discussed in comparison to other traditional organophosphorous agents. A detailed experimental analysis of the complexation patterns by means of a combination of IR, ¹H NMR and ESI-MS has revealed that the interaction of ether oxygen group in EG4IPE with metals and the corresponding extraction mechanism.     

Supercritical CO2 extraction of lutein esters from marigold (Tagetes erecta L.) enhanced by ultrasound

As a novel technique, supercritical CO₂ (SC-CO₂) extraction enhanced by ultrasound was applied to the extraction of lutein esters from marigold and the extraction curves were described by Sovová model. The mass transfer coefficient in the solid phase (k_s) increased from 3.1 × 10⁻⁹ to 4.3 × 10⁻⁹ m/s due to ultrasound. The effect of extraction parameters including particle size of matrix, temperature, pressure, flow rate of CO₂, and ultrasonic conditions consisting of power, frequency and irradiation time/interval on the yield of lutein esters were investigated with single factor experiments. The results showed that the yield of lutein esters increased significantly with the presence of ultrasound (p < 0.05). The maximal yield of lutein esters (690 mg/100 g) was obtained for a particle size fraction of 0.245–0.350 mm, extraction pressure of 32.5 MPa, temperature of 55 °C and CO₂ flow rate of 10 kg/h with ultrasonic power of 400 W, ultrasonic frequency of 25 kHz and ultrasonic irradiation time/interval of 6/9 s.     

Response surface optimization of Smyrnium cordifolium Boiss (SCB) oil extraction via supercritical carbon dioxide

In this study, the essential oil of aerial parts of a species of a plant called Smyrnium cordifolium Boiss (SCB) was extracted by supercritical CO₂. The essence was analyzed by the method of GC/MS. Design of experiments was carried out with response surface methodology by Minitab 16 software to optimize four operating variables of supercritical carbon dioxide (SC-CO₂) extraction (pressure, temperature, CO₂ flow rate and extraction dynamic time). This is the first report announcing optimization of the operation of supercritical extraction of SCB in laboratorial conditions. Optimizing process was done to achieve maximum yield extraction. Independent variables were dynamic time (t_d), pressure (P), temperature (T) and flow rate of SC-CO₂ (Q) in the range of 30–150 min, 10–30 MPa, 40–60 °C and 0.5–1.7 ml/min, respectively. The experimental optimal recovery of essential oil (0.8431, w/w%) was obtained at 13.43 MPa, 40 °C, 150 min (dynamic) and 1.7 ml/min (CO₂ flow rate).     

Micronization and characterization of squid lecithin/polyethylene glycol composite using particles from gas saturated solutions (PGSS) process

Lecithin was isolated from squid viscera residues after supercritical carbon dioxide (SC-CO₂) extraction at 25 MPa and 45 °C. The particle formation of squid lecithin with biodegradable polymer, polyethylene glycol (PEG) was performed by PGSS using SC-CO₂ in a thermostatted stirred vessel. By applying different temperatures (40 and 50 °C) and pressures (20–30 MPa), conditions were optimized. Two nozzles of different diameters (250 and 300 μm) were used for PGSS and the reaction time was 1 h. The average diameter of the particles obtained by PGSS at different conditions was about 0.74–1.62 μm. The lowest average size of lecithin particle with PEG was found by the highest SC-CO₂ density conditions with the stirring speed of 400 rpm and nozzle size of 250 μm. The inclusion of lecithin in PEG was quantified by HPLC. Acid value and peroxide value was measured after micronization of lecithin.     

Supercritical fluid extracts from tamarillo (Solanum betaceum Sendtn) epicarp and its application as protectors against lipid oxidation of cooked beef meat

The possibility of using the tamarillo (Solanum betaceum (Cav.) Sendtn (syn. Cyphomandra betacea)) epicarp as source of compounds with antioxidant activity in cooked beef meat (CBM) was explored. Extracts from tamarillo by supercritical fluid extraction (SFE) and Soxhlet extraction (SE) were obtained. The SFE was performed using pure CO₂ at different temperatures and pressures (40 and 50 °C; 10, 20 and 30 MPa) and CO₂ added with ethanol (CO₂/EtOH) as co-solvent (2, 5 and 8%, w/w). The SFE kinetics and mathematical modeling of the overall extraction curves (OEC) were also investigated. EtOH and hexane were used in the SE. The antioxidant activity (AA) of extracts was evaluated in CBM as well as the protection against lipid oxidation was determined by measuring lipid hydroperoxides (LHP) and thiobarbituric acid reactive species (TBARS). The extract obtained by SFE with CO₂/EtOH (50 °C/30 MPa and 2% of EtOH) showed the highest AA. In SFE, the co-solvent addition improved considerably the AA and the extraction yield. The extracts obtained by SFE with CO₂/EtOH showed a better AA compared with the synthetic antioxidant TBHQ. The highest yield values were achieved by SE with ethanol (7.7 ± 0.4%) and by SFE with 5% EtOH (1.9 ± 0.1%). The results indicate that extracts of tamarillo epicarp are a potential source of antioxidant compounds.     

Digestive enzymes characterization of krill (Euphausia superba) residues deoiled by supercritical carbon dioxide and organic solvents

In this study, Enzyme activities of krill were characterized before and after lipid extraction by supercritical carbon dioxide (SC-CO₂) and organic solvent, n-hexane and acetone. Krill SC-CO₂ extraction was performed under the conditions of temperature range from 35 to 45 °C and pressure, 150–250 bar for 2.5 h with a constant flow rate of 22 g/min. Extraction yields of lipids increased with pressure and temperature. The digestive enzyme activities of protease, lipase and amylase of SC-CO₂ treated krill residues were slightly decreased comparing to organic solvent, n-hexane and acetone treated residues. In SC-CO₂ treated samples, all of the digestive enzymes showed slightly higher temperature stability. In the other hand the crude extracts of SC-CO₂ and n-hexane treated krill samples showed almost same optimum pH and pH stability for each of the digestive enzymes. It was also found in SDS-PAGE that there are no significant differences in protein patterns of the crude extracts of untreated, SC-CO₂, n-hexane and acetone treated krill indicating no denaturation of proteins.     

Modelling of the inactivation kinetics of Escherichia coli,Saccharomyces cerevisiae and pectin methylesterase in orange juice treated with ultrasonic-assisted supercritical carbon dioxide

The combined effect of supercritical carbon dioxide (SC-CO₂) and high power ultrasound (HPU) on the inactivation kinetics of Escherichia coli, Saccharomyces cerevisiae and pectin-methyl esterase (PME) in orange juice was studied in order to select models that can predict their inactivation behaviour based on process parameters. Experiments were performed at different temperatures (31–41 °C, 225 bar) and pressures (100–350 bar, 36 °C). The inactivation rate of E. coli, S. cerevisiae and PME increased with pressure and temperature during SC-CO₂ + HPU treatments. The SC-CO₂ + HPU inactivation kinetics of E. coli, S. cerevisiae and PME were represented by models that included temperature, pressure and treatment time as variables, based on the Biphasic, the Peleg Type B, and the fractional models, respectively. The HPU-assisted SC-CO₂ batch system permits the use of mild process conditions and treatment times that can be even shorter than those of continuous SC-CO₂ systems.     

Supercritical extraction of carob kibbles (Ceratonia siliqua L.)

Carob pulp kibbles, a by-product of carob been gum production, was studied as a source of bioactive agents. Firstly, the carob kibbles were submitted to an aqueous extraction to extract sugars, and supercritical fluid extraction (SFE) was applied to the solid residue of that aqueous extraction, by using compressed carbon dioxide (SC-CO₂) as the solvent and a mixture of ethanol and water (80:20, v/v) as a co-solvent. Pressure and temperature were studied in the ranges 15–22 MPa, and 40–70 °C. Particle diameter, and co-solvent percentage in ranges of 0.27–1.07 mm, and 0–12.4%, respectively, were also studied, as well as the flow rate of SC-CO₂ between 0.28 and 0.85 kg h⁻¹, corresponding, respectively, to 0.0062 and 0.0210 cm s⁻¹ of superficial velocity. The extracts were characterised in terms of antioxidant capacity by DPPH method, and total phenolics content by the Folin–Ciocalteu method. The central composite non-factorial design was used to optimise the extraction conditions, using the Statistica, version 6 software (Statsoft). The best results, in terms of yield and antioxidant capacity, were found at 22 MPa, 40 °C, 0.27 mm particle size, about 12.4% of co-solvent and a flow rate of 0.29 kg h⁻¹ of SC-CO₂. The phenolics profile of the extracts obtained at these conditions was qualitatively evaluated by HPLC-DAD. The solid residue of the supercritical extraction was also studied showing to be a dietary fiber, which can be compared to Caromax™, a carob fiber commercialised by Nutrinova Inc.     

Effects of supercritical CO2 extraction parameters on chemical composition and free radical-scavenging activity of pomegranate (Punica granatum L.) seed oil

Pomegranate (Punica granatum L.) seed oil (PSO) was prepared by supercritical CO₂ (SC-CO₂) extraction technology. Changes in the yield, chemical composition and free radical-scavenging activity of PSO under different extraction parameters were investigated. The results of SC-CO₂ extraction revealed that extraction pressure was the dominant factor to affect the oil yield. PSO was characterized by a high content of punicic acid (approximately 60%) and γ-tocopherol (more than 300 mg/100 g oil). A slight increase in the contents of punicic acid, arachidic acid and gadoleic acid was observed under higher extraction pressure and temperature. At lower pressure or shorter extraction time, PSO with high amount of total tocopherols was obtained. PSO extracted by SC-CO₂ showed strong free radical-scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenz-thiazoline-6-sulfonic) diammonium salt (ABTS) radicals and its scavenging ability was correlated with the level of tocopherols in extracted oils.     

Effects of supercritical CO2 extracts of Melia azedarach L. on the control of fall armyworm (Spodoptera frugiperda)

This work reports the use of Melia azedarach L. extracts obtained from supercritical carbon dioxide extraction (SC-CO₂) as an insecticidal agent against fall armyworm (Spodoptera frugiperda). For this purpose, SC-CO₂ extractions were performed, varying the pressure (150–250 bar), temperature (313–333 K), sample particle size and extraction time. Secondary metabolites from the classes of coumarins, sterols and terpenes were identified in the extracts, with the triterpene melianone being the major constituent. For the biological activity tests, diets were prepared with different SC-CO₂ extract concentrations (100, 500, 1000 and 5000 mg/kg) and offered to S. frugiperda (Lepidoptera: Noctuidae). The results indicated that mortality increased with increasing extract concentrations with 50% mortality (LC₅₀) at a concentration of 376.74 mg/kg and reaching 100% mortality at 5000 mg/kg. The inhibition of insect growth was observed at higher concentrations due to the antifeedant action of the extract. At the lowest extract concentration (100 mg/kg), ingestion caused low pupal viability and adults presenting morphological deformities, which thus indicated a chronic toxicity effect.     

Supercritical carbon dioxide extraction of squalene and tocopherols from amaranth and assessment of extracts antioxidant activity

Squalene and tocopherols are the most important bioactive constituents in lipophilic amaranth fraction. Therefore, developments of processes of isolation of amaranth extracts enriched with these compounds are of interest. In this study the lipophilic fraction of amaranth seeds was extracted by supercritical fluid extraction with carbon dioxide (SCE-CO₂) under different pressure conditions and by adding 2 and 5% of cosolvent ethanol. The yield of extract varied from 1.37 (15 MPa without cosolvent) to 5.12% (55 MPa and 5% of cosolvent). The highest content of unsaponifiables (21.1%) in the extract was at 55 MPa and 5% of cosolvent; at these conditions the yields of tocopherols and squalene from amaranth seeds were 317.3 mg/kg and 0.289 g/100 g, respectively. Tocopherol isomers in amaranth oil were distributed at the approximate ratio of 1(α-T):27(β-T):6.5(γ-T):5(δ-T). The extract was fractionated in the two separators by gradual decrease of the pressure and it was found that the fraction obtained at ambient conditions contained the highest concentration of tocopherols (up to 7.6 mg/g) and squalene (up to 17.9 g/100 g oil). The highest antioxidant activity measured by the L-ORAC assay possessed the fractions with the highest concentrations of squalene and tocopherols and obtained at 15 MPa with pure CO₂ (235.1 μmol TE/g) and 2% of cosolvent (257.6 μmol TE/g).     

Obtaining phenolic compounds from jatoba (Hymenaea courbaril L.) bark by supercritical fluid extraction

The extraction of polyphenol compounds from jatoba (Hymenaea courbaril L. var stilbocarpa) bark using supercritical fluid extraction (SFE) with CO₂ and cosolvents has been investigated. Among the solvent systems studied, SFE using CO₂ and water (9:1, v/v), at 323 K and 35 MPa, presented the best results, with extract yield of 24%, and with high antioxidant activity (IC₅₀ of 0.2 mg/cm³). This solvent system was used to determine global yield isotherms, which were built at 323 and 333 K, and 15, 25, and 35 MPa, using a second lot of jatoba. The highest yield was 11.5% at 15 MPa and 323 K, with maximum total phenolic compounds (TPC) of 335.00 mg TAE/g extract (d.b.) and total tannins content of 1.8 g/100 g raw material. A kinetic experiment was performed using optimized conditions, yielding 18% extract, and the kinetic parameters were used to scale-up the process from laboratory to pilot scale. Chemical analyses showed high content of phenolic compounds in the extracts of jatoba bark mostly due to the presence of procyanidins.     

Enzymatic conversion of corn oil into biodiesel in a batch supercritical carbon dioxide reactor and kinetic modeling

Synthesis of fatty acid methyl esters (FAME) as biodiesel from corn oil was studied in a batch supercritical carbon dioxide (SC-CO₂) bioreactor using immobilized lipase (Novozym 435) as catalyst. Effects of reaction conditions on the contents of FAME, monoacylglycerols (MAG), diacylglycerols (DAG), and triacyglycerols (TAG) were investigated at various enzyme loads (5–15%), temperatures (40–60 °C), substrate mole ratios (corn oil:methanol; 1:3–1:9), pressures (10–30 MPa), and times (1–8 h). The highest FAME content (81.3%) was obtained at 15% enzyme load, 60 °C, 1:6 substrate mole ratio, and 10 MPa in 4 h. A reaction kinetic model was used to describe the system, and the activation energy of the system was calculated as 72.9 kJ/mol. Elimination of the use of organic solvents, chemical catalysts and wastewater as well as reasonably high yields make the enzymatic synthesis of biodiesel in SC-CO₂ a promising green alternative to conventional biodiesel process.