Three phase partitioning coupled with ultrasound for the extraction of ursolic acid and oleanolic acid from Ocimum sanctum

In this study, three phase partitioning (TPP) is coupled with ultrasound for the extraction of ursolic acid (UA) and oleanolic acid (OA) from Ocimum sanctum leaves and process has been optimized to obtain maximum recovery. TPP is a relatively novel bioseparation technique used for the extraction, concentration and purification of enzymes and natural products. The technique of TPP was explored for the extraction of ursolic acid (UA) and oleanolic acid (OA) from O. sanctum leaves. The influence of various process parameters (pH, ammonium sulfate saturation, crude extract to t-butanol ratio, time and feed loading) on the extraction efficiency was investigated to get highest yield. The optimized conditions were found to be as follows: time – 120 min, pH – 7, ammonium sulfate saturation – 50% w/v, crude extract to t-butanol ratio – 1:1 and feed loading – 7.5% w/v. The highest yield obtained for UA and OA was 79.48% and 80.67% respectively under optimized conditions of TPP. Compared with TPP higher yield (83.36% and 85.58%) was obtained by ultrasound assisted TPP (UATPP) at 40 kHz and 180 W power and the time required was only 14 min as compared to 120 min of TPP. The extraction yield obtained was also compared with conventional solvent extraction and TPP-ultrasound was found to be an attractive technique for the extraction of UA and OA from O. sanctum leaves.     

Enzyme and high pressure assisted extraction of carotenoids from tomato waste

Enzyme (EA) and high pressure (HP) assisted extraction of carotenoids, especially lycopene, from tomato waste using various organic solvents was examined. Total carotenoid and lycopene extraction yields were increased by the use of pectinase and cellulase enzymes, when compared to the non enzyme treated solvent extraction process. The increase of extraction yield depended on the solvent. Maximum total carotenoid (127 mg/kg d.w.) and lycopene (89.4 mg/kg d.w.) extraction yields were obtained in enzyme treated samples extracted with ethyl lactate (solvent:solid = 10:1 mL:g), corresponding to almost 6-fold and 10-fold increase, respectively, with respect to non enzyme treated samples. HP assisted extraction led to higher extraction yields (from 2 to 64% increase depending on the solvent used) compared to conventional solvent extraction process performed at ambient pressure for 30 min. HP assisted solvent extraction was successfully performed at 700 MPa by using significantly (P < 0.05) lower ratios of solvent:solid (6:1 and 4:1 mL:g) and reduced processing time (10 min), compared to solvent extraction performed at ambient pressure, solvent:solid ratio 10:1 mL:g and 30 min extraction time.     

Pressurized hot water extraction of β-glucans from waxy barley

Pressurized hot water (PHW) is a new and promising solvent for the extraction of β-glucans from cereals. The effect of temperature, extraction time and pressure has been studied for the extraction of β-glucans from waxy barley (6.0% in β-glucans). Extraction yield, molecular weight and degradation products have been evaluated. Temperature (110–180 °C) and extraction time (15–75 min) showed a strong influence on extraction process. Extraction yield and MW are optimized for 155 °C, 18 min and 50 bar, leading to 53.7% extraction yield and 200 kDa. The presence of degradation products, such as HMF, is negligible under these conditions. The comparison between these optimal results and that from a conventional process (55 °C, 3 h and ambient pressure) reveals a big difference in MW (200 kDa vs. 55 kDa, respectively). PHW causes a significantly reduction in extraction time and an increase of β-glucan MW of almost 4 times as major benefits.     

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.     

Effect of Process Parameters on Solute Centrifugal Extraction from Electropermeabilized Carrot Gratings

The solute aqueous centrifugal extraction from carrot gratings was investigated through the effect of some process parameters (centrifugal acceleration, solution temperature and liquid to solid ratio). The carrot gratings were treated by a pulsed electric field (PEF) (670 V cm⁻¹ and 300 pulses of 100 μs) and then subjected to an aqueous centrifugal extraction (accelerations from 14 × g to 5434 × g) at temperatures in the range 18–35°C. The effect of carrot tissue mild preheating (30–50°C) before PEF was also investigated.The increase of centrifugal acceleration up to 150 × g enhances extraction kinetics. The solute concentration then reaches 96% after 25 min of extraction at room temperature or after 15 min of extraction at 35°C. However, any further increase in centrifugal acceleration does not provide more acceleration of extraction. A tissue preheating at 50°C allowed an easier electrical permea-bilisation of cell membranes at lower PEF intensity (300 V cm⁻¹) and shorter PEF extent (30 pulses). A maximum solute yield is then obtained. The kinetics of centrifugal aqueous extraction was described by a single exponential model.     

Extraction of ursolic acid from Ocimum sanctum leaves: Kinetics and modeling

Ursolic acid (UA) is a triterpene compound which shows significant biological potential. This study deals with the optimization and kinetics of UA extraction from Ocimum sanctum (OS) leaves in a stirred batch extraction. The influence of various extraction parameters on the extraction yield has been studied. The optimum extraction conditions were extraction time 40 min, speed of agitation 1000 rpm, temperature 323 K, solute to solvent ratio of 1:120. This resulted in 11.21 mg of UA/g of dried leaf powder of OS. The extraction kinetics behavior of UA from OS revealed that the extraction of UA followed a first order kinetics. The kinetic expression developed by Spiro and Siddique was used and the model is in good agreement with the experimental results. The diffusion coefficient determined ranged from 2 × 10^?11 to 6.10 × 10^?11 m²/s for the all set of experiments. The activation energy for the extraction of UA was found to be E_a = 10.45 kJ/mol.     

Extraction of phenolic compounds from pitanga (Eugenia uniflora L.) leaves by sequential extraction in fixed bed extractor using supercritical CO2, ethanol and water as solvents

With the goal of maximizing the extraction yield of phenolic compounds from pitanga leaves (Eugenia uniflora L.), a sequential extraction in fixed bed was carried out in three steps at 60 °C and 400 bar, using supercritical CO₂ (non-polar) as solvent in a first step, followed by ethanol (polarity: 5.2) and water (polarity: 9.0) in a second and third steps, respectively. All extracts were evaluated for global extraction yield, concentration and yield of both polyphenols and total flavonoids and antioxidant activity by DPPH method (in terms of EC₅₀). The nature of the solvent significantly influenced the process, since the extraction yield increased with solvent polarity. The aqueous extracts presented higher global extraction yield (22%), followed by ethanolic (16%) and supercritical extracts (5%). The study pointed out that the sequential extraction process is the most effective in terms of global extraction yield and yield of polyphenols and total flavonoids, because it produced the more concentrated extracts on phenolic compounds, since the supercritical ethanolic extract presented the highest phenolics content (240.5 mg GAE/g extract) and antioxidant capacity (EC₅₀ = 9.15 μg/mL). The most volatile fraction from the supercritical extract, which is similar to the essential oils obtained by steam distillation or hydrodistillation, presented as major compounds the germacrenos D and B + bicyclogermacrene (40.75%), selina-1,3,7(11)-trien-8-one + selina-1,3,7(11)-trien-8-one epoxide (27.7%) and trans-caryophyllene (14.18%).     

Extraction optimization of oleanolic and ursolic acids from pomegranate (Punica granatum L.) flowers

An ecofriendly ultrasonic-assisted extraction (UAE) technique was developed for rapid extraction of bioactive compounds oleanolic and ursolic acids from pomegranate flowers. Several different influential extraction parameters, such as ultrasonic power, extraction time, solvent type, aqueous ethanol concentration, loading ratio and extraction temperature, were investigated. The optimum extraction conditions were 90% ethanol solution as solvent, ultrasound power 150 W, the liquid:material ratio of 20:1 (v/w) and extraction for 50 min at 40 °C. Scanning electron microscopy showed that ultrasonic treatment resulted in a number of pits on cells of pomegranate flowers. Extracts obtained from 30 min of UAE showed higher antioxidant activity than those of other conventional methods. The UAE method was more efficient than classical methods included maceration, stirring extraction and heat reflux extraction.     

Effects of supercritical CO2 extraction parameters on soybean oil yield

A series of operational parameters of supercritical fluid extraction of soybean oil (pressure: 300–500 bar, temperature: 40–60 °C, CO₂ mass flow rate: 0.194–0.436 kg/h and characteristic particle size: 0.238–1.059 mm) were investigated in a laboratory scale apparatus. The results show that the extraction yields were significantly affected by applied operational extraction parameters. The increase in pressure, temperature and solvent flow rate improved the extraction yield. The extraction yield increased as the particle size decreased depending on decreasing intra-particle diffusion resistance. To describe the extraction process Sovova's model was used and very good agreement with the experimental results was obtained. Based on the experimental data the internal and external mass transfer coefficients were estimated. To explore the influence of the extractor size on this process, soybean samples were extracted using different extraction basket volumes (0.2 L and 5 L) and related model parameters were examined. The mass transfer coefficient in the fluid phase increased with the increase in extractor size, while the mass transfer coefficient in the solid phase was independent of the extractor size.     

Integrated supercritical fluid extraction and subcritical water hydrolysis for the recovery of bioactive compounds from pressed palm fiber

Pressed palm fiber (PPF), a residue obtained from palm oil industry, is a source of bioactive compounds, such as carotenoids, which are used as food additives. It also has cellulose and hemicellulose that can be used to yield fermentable sugars for the production of second generation ethanol. Supercritical fluid extraction (SFE) of pressed palm fiber provides an oil rich in carotenoids while subcritical water hydrolysis (SubWH) produces hydrolysates with high amounts of fermentable sugars. In this work, the effects of pressure (15–30 MPa) and temperature (318 and 328 K) on SFE of carotenoids were investigated. The SFE extract with highest carotenoid content was obtained at 318 K and 15 MPa (2.3% d.b., 0.81 mg β-carotene/g extract). After the extraction, the influence of process temperature (423–633 K), pressure (15 and 25 MPa), solvent:feed ratio (120 and 240), and residence time (1.25–5 min) on SubWH of the extraction residue was studied. At the temperature of 523 K, the highest total reducing sugar yield (11–23 g glucose/100 g carbohydrate) and the highest biomass conversion (40–97%) were obtained for any pressure and solvent:feed ratio. The highest selectivity for saccharide formation was found at 423 K (20–59 mol glucose/mol furfural equivalent). Optimal conditions for high saccharide formation and low sugar degradation product in subcritical hydrolysis were obtained at 523 K, 15 MPa, solvent:feed ratio of 120, residence time of 2.5 min with a total reducing sugar yield of 22.9 g glucose/100 g carbohydrate and a conversion of 84.9%.     

Mathematical modeling and mass transfer considerations in supercritical fluid extraction of Posidonia oceanica residues

Posidonia oceanica residues were extracted with supercritical CO₂ in order to isolate phenolic compounds. The process was optimized by developing a mathematical model based on mass transfer mechanism consisting of adsorption of supercritical fluid on the solid particles, desorption of solute and convective transfer of solute phase along the column. Henry relation between solute concentrations on the surface of the solid (Cs) and in the solid (q) was approximated in order to describe the adsorption/desorption equilibrium. The model parameters such as solid-liquid film mass transfer coefficient (kf), molecular diffusivity coefficient (D_AB) and axial dispersion (D_ax) were estimated using empirical methods. The linear driving force model was applied to improve the yield of total phenolic acid recovery. The optimum parameters were elicited as 25 MPa, 323.15 K and a co-solvent mass ratio of 20% yielding 34.97 μg per gram of dry feed and the model satisfactorily described the extraction yield which can be used for scale-up purposes.     

Extraction of bioactive components from Centella asiatica using subcritical water

Bioactive components, asiatic acid and asiaticoside, were extracted from Centella asiatica using subcritical water as an extraction solvent. Extraction yields of asiatic acid and asiaticoside were measured using high-performance liquid chromatography (HPLC) at temperatures from 100 to 250 °C and pressures from 10 to 40 MPa. As temperature or pressure increased, the extraction yield of asiatic acid and asiaticoside increased. At the optimal extraction conditions of 40 MPa and 250 °C, the extraction yield of asiatic acid was 7.8 mg/g and the extraction yield of asiaticoside was 10.0 mg/g. Extracted asiatic acid and asiaticoside could be collected from water as particles with a simple filtering process. Dynamic light scattering (DLS) was used to characterize particle size. Particles containing asiatic acid were larger (1.21 μm) than particles containing asiaticoside (0.76 μm). The extraction yields of asiatic acid and asiaticoside using subcritical water at 40 MPa and 250 °C were higher than extraction yields using conventional liquid solvent extraction with methanol or ethanol at room temperature while the subcritical water extraction yields were lower than extraction yields with methanol or ethanol at its boiling point temperature.     

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.     

Determination of sulfonylurea herbicides in soil samples via supercritical fluid extraction followed by nanostructured supramolecular solvent microextraction

The present work describes a sensitive procedure for extraction and determination of three sulfonylurea herbicides (metsulfuron-methyl, bensulfuron-methyl and chlorsulfuron) in water samples using supramolecular solvent microextraction. A supramolecular solvent with a nano structure made up of decanoic acid assemblies dispersed in tetrahydrofuran and water was proposed. Also, a supercritical fluid extraction coupled with supramolecular solvent microextraction was applied for extraction and determination of ultra-trace amounts of sulfonylurea herbicides in soil samples. A Taguchi orthogonal array experimental design with an OA₁₆ (4⁵) matrix was employed to optimize the supercritical fluid extraction conditions. In supercritical fluid extraction–supramolecular solvent microextraction procedure, a mixture of decanoic acid and the SFE collecting solvent (tetrahydrofuran) was added to water for supramolecular solvent formation. The effective parameters on the supramolecular solvent microextraction efficiency were studied and optimized using two different optimization methods: one variable at a time and face centered design. Under the optimum conditions, linear dynamic ranges varied within 0.1–5 mg kg⁻¹ (0.9978 ≤ R² ≤ 0.9987) and 0.5–100 μg L⁻¹ (0.9973 ≤ R² ≤ 0.9995) for all of the sulfonylurea herbicides in the supercritical fluid extraction–supramolecular solvent microextraction and supramolecular solvent microextraction, respectively. The intraday (n = 5) and interday standard deviations were calculated by extracting the SUHs from water and soil samples through supramolecular solvent microextraction and supercritical fluid extraction–supramolecular solvent microextraction. Interday RSDs% lower than 7.1% and intraday RSDs% lower than 3.8% were obtained. Limits of detection, based on a S/N ratio of 3, were 0.5 μg L⁻¹ and 0.7 mg kg⁻¹ for supramolecular solvent microextraction and supercritical fluid extraction–supramolecular solvent microextraction, respectively.     

Separation of glycyrrhizic acid from licorice root extract using macroporous resin

Glycyrrhizic acid (GA) is the major active ingredient of licorice which has many pharmacological activities. In the present study, separation of GA from licorice root extract has been carried out by adsorption on five different macroporous resins. Static and dynamic adsorption of GA from crude licorice root extract is studied on ion exchange resins followed by desorption. Indion 810 shows the maximum adsorption as well as desorption capacity. The adsorption experiments indicate that equilibrium can be achieved in 360 min. The adsorption equilibrium data is well fitted in the Langmuir isotherm. The separation process is optimized by investigating the effect of pH on adsorption capacity and effect of concentration of ethanol on desorption capacity. The dynamic adsorption is carried out in a column packed with Indion 810 resin and effect of feed flow rate and initial concentration of GA in extract has been studied. The results showed that increase in feed flow rate as well as initial feed concentration of GA lowers the dynamic binding capacity and mass transfer coefficient while increases the HETP. The purity of GA is increased from 14.3% to 71.5% by the dynamic desorption with 60% ethanol. Indion 810 resin can efficiently separate GA from licorice root extract with the HPLC recovery of 63.6%. This study forms the basis for large scale preparation of GA by resin adsorption.     

Influence of the bed geometry on the kinetics of the extraction of clove bud oil with supercritical CO2

There is a need for scientific research that evaluates the influence of important process variables on the scale up of supercritical technology. For supercritical fluid extraction (SFE), one of these variables is the extractor's bed geometry, which can be defined by the ratio of the bed height (H_B) to the bed diameter (D_B). A systematic study is needed to select suitable criteria that can be used to obtain similar extraction curves among beds with different geometries. In this study, maintaining a constant ratio of solvent mass to feed mass for two beds with 1-L volumes but different geometries (E-1: H_B/D_B = 7.1; E-2: H_B/D_B = 2.7) was confirmed as a successful scale up criterion. For constant values of the temperature, pressure and bed porosity, there is experimental evidence that the mass transfer rate is equal in the two beds when the solvent flow rate is high. When 0.6 kg of clove buds was packed in the beds, the extraction rates were 2.10 ± 0.08 and 2.3 ± 0.1 g extract/min for beds E-1 and E-2, respectively. However, when the solvent flow rate was lower, the extraction rates were 0.93 ± 0.06 and 1.12 ± 0.02 g extract/min for beds E-1 and E-2, respectively. This difference in behavior between the extraction beds is associated with the axial dispersion of the fluid, which is more pronounced when the H_B/D_B ratio is increased. Thin particles tend to compact in the beds with high H_B/D_B ratios, which shorten the solvent passage. Non-isothermal profiles and differences in chemical composition of the extracts were also observed: 17% more α-humulene and 9% more eugenol were extracted in E-1 and E-2, respectively.     

Pressurized liquid extraction and low-pressure solvent extraction of carotenoids from pressed palm fiber: Experimental and economical evaluation

In this work, a comparison of Soxhlet extraction (LPSE–SOX), percolation (LPSE–PE) and pressurized liquid extraction (PLE) for the recovery of carotenoid-rich extracts from pressed palm fiber (PPF) was carried out in terms of yield, carotenoid profile and economic viability to evaluate the methods’ industrial applicability. An optimization study was performed for each extraction technique with ethanol at a solvent/feed ratio of 20. The independent variables were temperature (35–55 °C), pressure (0.1–8 MPa) and flow rate (1.6, 2.4 g/min). The results showed that the global extraction yield obtained using LPSE–SOX (96 ± 4 mg extract/g PPF d.b.) after 6 h was higher than that obtained using LPSE–PE (74 ± 5 mg extract/g PPF d.b., 35 °C, 2.4 g/min) or PLE (44 ± 3 mg extract/g PPF d.b., 55 °C, 4 MPa, 2.4 g/min) after dynamic extraction time of 17 min under optimized conditions. On the other hand, the carotenoid yield obtained using PLE (305 ± 18 μg α-carotene/g extract and 713 ± 46 μg β-carotene/g extract) was higher than the obtained by LPSE–SOX (142 ± 13 μg α-carotene/g extract and 317 ± 46 μg β-carotene/g extract). PLE technique showed the highest selectivity for carotenoids than LPSE techniques. The lowest cost of manufacturing (COM) were obtained for LPSE–PE and PLE with values of US$13.4 and US$29.2/kg extract for a 0.5 m³ vessel capacity.     

Extraction of jojoba oil with liquid CO2 + propane solvent mixtures

In this work liquid CO₂/propane mixtures were used to extract jojoba oil from oilseeds. First, experiments at 313 K and pressures of 70 bar and 200 bars were carried out on jojoba oil deposited on glass spheres, using different solvent concentrations (30 wt%, 50 wt% and 70 wt% CO₂), to assess the influence of the solvent composition and phase behavior on the extraction rate. Then, jojoba oil was extracted from the milled seeds under homogeneous liquid conditions, using solvent mixtures containing 30 wt% and 50 wt% CO₂ at 70 bar and 313 K. A solvent mixture with 30 wt% CO₂ exhibited good solvent power. Oil extraction yields of 98% were obtained using a minimum solvent to oilseed mass ratio of 5 g solvent/g oilseed and operating the extractor at 313 K and 70 bar.     

Pressurized limonene as an alternative bio-solvent for the extraction of lipids from marine microorganisms

A fast and green process for the isolation of high value lipids from different marine microorganisms is presented involving the use of limonene, a green biodegradable solvent, as an alternative to traditional hexane extraction. The optimized process is based on pressurized liquid extraction (PLE) at 200 °C for 15 min using limonene:ethanol (1:1, v/v) as extracting solvent. Under these conditions, lipids were extracted from different microalgae such as Spirulina, Phormidium, Anabaena and Stigeoclonium and their composition in terms of fatty acids were studied by using a Fast-GC–MS method and compared with the original content in the raw material. The extraction method provided the best results in terms of extraction yield for Spirulina, meanwhile the highest amount of ω-3 fatty acids were obtained from Stigeoclonium.     

Experimental measurement and modelling with Aspen Plus® of the phase behaviour of supercritical CO2 + (n-dodecane + 1-decanol + 3,7-dimethyl-1-octanol)

Experimental phase equilibrium data for the systems CO₂ + n-dodecane, CO₂ + 1-decanol and CO₂ + 3,7-dimethyl-1-octanol were used to determine values for binary interaction parameters for use in the RK-ASPEN thermodynamic model in Aspen Plus^®. Bubble and dew point data of the mixtures CO₂ + (n-dodecane + 1-decanol), CO₂ + (n-dodecane + 3,7-dimethyl-1-octanol), CO₂ + (1-decanol + 3,7-dimethyl-1-octanol) and CO₂ + (n-dodecane + 1-decanol + 3,7-dimethyl-1-octanol) were measured experimentally in a static synthetic view cell, and compared to the data predicted by the RK-ASPEN model. The model predicted the phase equilibrium data reasonably well in the low solute concentration region; significant deviation of model predictions from experimental data occurred in the mixture critical and high solute concentration regions due to the exclusion of solute–solute interaction parameters in the model. Distribution coefficients and separation factors were determined for the multi-component mixture and separation of the alkane from the alcohol mixture with a supercritical fluid extraction process was found to be possible.