Study on the pilot-scale extraction of onion oleoresin using supercritical CO2

Supercritical carbon dioxide (SC-CO₂) was used to produce oleoresin from dried onion by pilot-scale extraction. The results showed that the extraction pressure and temperature affected the yield and sulphur concentration of onion oleoresin. Increase of the temperature from 45 to 65°C at 300 bar resulted in an increase of the yield and the sulphur concentration of oleoresin. At the same temperature (45°C) the yield was also higher at 300 bar than 100 bar while sulphur concentration of oleoresin got smaller at 300 bar than at 100 bar. The volatile composition of oleoresin displayed practically no differences as a function of extraction parameters. Comparison of different extraction methods showed that the yield after SC-CO₂ extraction was 22 times higher than that after steam distillation, but it was 14 or 39 times less than that after alcohol extraction, shaking at 25°C or in Soxhlet apparatus, respectively. The concentration of sulphur was the highest in steam distilled onion oil while it was the lowest in the extract of hexane and alcohol (at 25°C). The results of sensory evaluation showed that oleoresin extracted by SC-CO₂ was the first in ranking (at level of significance 0·05), before steam distilled oil and alcoholic extract. There was no significant difference between steam distilled oil and alcoholic extract in ranking, but the alcoholic extract was the least desirable, since the intensity of its off odour attribute was the highest. © 1998 SCI.     

Supercritical CO₂extraction of oleoresin from marigold (Tagetes erecta L.) flowers and determination of its antioxidant components with online HPLC-ABTS(·+) assay

BACKGROUND: Marigold is a traditional medicine herb which shows good pharmacological activity in many aspects. It is very important to obtain and investigate the specific bioactive compounds from marigold. The objective of the study was to extract the oleoresin from marigold with supercritical CO₂ (SC‐CO₂) at different pressures and temperatures, detect the fatty acid composition by gas chromatography–mass spectrometry and investigate the antioxidative components in the extracts by combined online high‐performance liquid chromatography‐2,2‐azinobis‐(3‐ethylbenzothiazolin‐6‐sulfonic acid (HPLC‐ABTS^?+) post‐column assay and HPLC‐tandem mass spectrometry. RESULTS: For the pressure range (20–40 MPa) and temperature range (30–70 °C), 30 MPa/70 °C gave the highest yield of oleoresin (58.9 g kg^?1). The dominant fatty acids of marigold flower oleoresin were linoleic acid (>26.41%), palmitic acid (>24.22%) and oleinic acid (>20.12%). Significant effects of the extraction pressure and temperature on the antioxidant activity were observed (P < 0.05). Lutein esters, α‐tocopherol, β‐tocopherol, γ‐tocopherol and δ‐tocopherol were the dominant antioxidant compounds in the extracts. CONCLUSION: The study has shown that the yield and total antioxidant activity of the marigold extracts were affected by the pressure and temperature of SC‐CO₂, and that online HPLC technique could be used as an efficient and rapid method for separation and identification of bioactive compounds from a complex mixture. Copyright © 2011 Society of Chemical Industry     

Optimisation of supercritical CO2 extraction of grape seed oil using response surface methodology

The aim of this study was to use waste from the wine production process with special accent on grape seeds and new green technology. Supercritical CO₂ was considered as a green solvent in extraction of grape seed oil. The effects of different extraction process parameters on oil yield and antioxidant activity were investigated. Extraction optimisation was conducted using response surface methodology (RSM). Extraction pressure has proven to be the most significant factor influencing oil yield and antioxidant activity (P < 0.0001). The optimal conditions for obtaining the highest oil yield and antioxidant activity within the experimental range of the variables studied were at extraction pressure of 400 bar and temperature of 41 °C. Under these optimal conditions, the predicted extraction oil yield was 14.49% and DPPH 37.07%. Applying this green extraction method, the oil from grape seeds was totally extracted. The produced oil was of satisfactory quality, and the content of α‐tocopherol in obtained grape seed oil at optimal extraction conditions was 36.05 mg kg^?1.     

Supercritical CO2 extraction of Chilean hop (Humulus lupulus) ecotypes

Hops (Humulus lupulus L) have very stringent requirements of diurnal light hours during flowering. Thus, the beer industry is permanently assessing new agricultural land to grow hops, southern Chile being an excellent candidate for their introduction. Supercritical carbon dioxide extraction procedures were implemented to assess Chilean hop ecotypes. Based on results of a preliminary study with commercial samples (cv Nugget), 200 bar and 40 °C were selected as extraction conditions. Very limited increases in extraction rate were observed when applying pressures >200 bar; such pressures did not speed up the extraction of α‐acids (bitter flavor principles), but rather increased the co‐extraction of undesirable compounds (hard resins and chlorophyll pigments). On the other hand, the effects of retrograde condensation phenomena were just starting to subside at 200 bar, and thermal damage of samples could increase at >40 °C. Ground cone samples of five local hop ecotypes, originating from Osorno, La Junta, Coyhaique and Elizalde Lake, were subsequently tested. Osorno exhibited a higher yield (65 g kg^?1 oleoresin/substrate) than other Chilean ecotypes. Moreover, Osorno extract had a light yellowish color, as well as a higher content of bitter flavors (157 g kg^?1 α‐acid/extract) and 1.5–7.1 times more representative aroma compounds than extracts of the other ecotypes. However, all these indicators were very low compared with the commercial Nugget sample (134 g kg^?1 oleoresin/substrate, 383 g kg^?1 α‐acid/extract, 14 times more aroma compounds than Osorno ecotype). Copyright © 2003 Society of Chemical Industry     

Subcritical fluid extraction of Lycium ruthenicum seeds oil and its antioxidant activity

The effective, energy-saving and green subcritical fluid extraction (SFE) technology was applied to obtain the oil from Lycium ruthenicum seeds (LRSO). The optimal conditions of extraction parameters were found using response surface methodology with Box-Behnken experimental design. The maximum extraction yield of 21.20% was achieved at raw material particle size of 0.60 mm, extraction pressure of 0.63 MPa, temperature of 50 °C and time of 48 min. Other traditional extraction technologies were comparatively used. The physicochemical property of LRSO was analysed and the chemical compositions indicated that they were rich in unsaturated fatty acid, β-carotene, tocopherols and total phenolics. Furthermore, the antioxidant activity of LRSO was evaluated by scavenging activity of three kinds of radicals (DPPH·, ·OH and O₂^-·) and lipid peroxidation in vitro. And its results showed the oil had the potential to be a novel antioxidant agent for using in the field of food, pharmaceuticals and cosmetics.     

Characterization of Valuable Compounds from Winter Melon (<Emphasis Type="Italic">Benincasa hispida</Emphasis> (Thunb.) Cogn.) Seeds Using Supercritical Carbon Dioxide Extraction Combined with Pressure Swing Technique

In this study, we describe the extraction of different valuable compounds from winter melon seeds using supercritical carbon dioxide extraction combined with pressure swing technique (SCE-PST). The effects of the extraction variables, namely pressure, holding time (HT), and continuous extraction time (CT), were optimized by response surface methodology (RSM) to maximize the crude extraction yield (CEY). The optimal conditions were at pressure of 181.35 bar, HT of 9.93 min, and CT of 50.14 min. Under these conditions, the experimental CEY was 235.70?±?0.11 mg g^?1 with a relatively strong antioxidant activity (64.42?±?0.21 % inhibition of DPPH^· radicals, 67.36?±?0.34 % inhibition of ABTS^·+ radicals) and considerable amount of phenolic compounds (42.77?±?0.40 mg gallic acid equivalent/g extract). The high-performance liquid chromatography (HPLC) analysis revealed that the bioactive phenolic compounds increased significantly using PST (p?<?0.05), where gallic acid had the highest concentration (0.688?±?0.34 mg g^?1). The extract obtained using optimal SCE-PST conditions contained more than 83.65 % total unsaturated fatty acids (UFAs) and linoleic acid accounted for 67.33?±?0.22 % in the total extract. From the results, the SCE efficiency in terms of extract quantity and quality has been enhanced significantly applying PST. Finally, the results were compared with previous published findings using supercritical carbon dioxide, ultrasound-assisted, and Soxhlet extraction. It was found that higher CEY could be achieved using Soxhlet extraction even through the quality of SCE-PST extracts in terms of antioxidant activity and phenolic compounds was better.     

Supercritical CO2 extraction of allicin from garlic flakes: Screening and kinetic studies

The nutraceutical industry is currently interested in obtaining garlic extracts using mild extraction processes to recover high levels of labile allicin. This work studied oleoresin yield and extraction selectivity for allicin in the supercritical CO₂ extraction of freeze-dried aqueous garlic homogenate as a function of sample conditioning and process conditions. Agglomeration phenomena, which is responsible for substrate lumps in packed beds and flow channeling in the bed during extraction, was avoided by lowering sample moisture below 31 g kg^? 1 water/substrate, and/or process temperature below 65 °C. Oleoresin yield increased slightly with extraction pressure (15–45 MPa) and dramatically with process temperature (35–65 °C), but the concentration of allicin in the extract decreased as the temperature increased. Thus, an optimal combination of intermediate temperature and pressure was selected that allowed reasonably large yields (≥ 19 g kg^? 1 oleoresin/substrate) and extraction selectivities (≥ 75 mg kg^? 1 allicin/oleoresin). Based on experimental results, a 4 h extraction process at 55 °C and 30 MPa using 55 kg kg^? 1 CO₂/substrate was recommended. Cumulative extraction plots for oleoresin and allicin were successfully adjusted using a linear driving force mass transfer model.     

Optimization of supercritical CO2 extraction of phytosterol-enriched oil from Kalahari melon seeds

Supercritical carbon dioxide (SC-CO₂) extraction of oil from Kalahari melon seeds was investigated in this study. Response surface methodology was applied to model and optimize the extraction, namely pressure (200–400 bar), temperature (40–80 °C), and supercritical fluid flow rate (10–20 mL/min). Well-fitting models were successfully established for oil recovery (R ² = 0.9672) and phytosterol concentration (milligrams per 100 g; R ² = 0.8150) through multiple linear regressions with backward elimination. The effect of supercritical fluid flow rate was the most significant (P < 0.05) factor that affected oil recovery but this factor had no significant (P > 0.05) effect on phytosterol concentration. The optimal processing conditions for oil recovery and phytosterol concentration were pressure of 300 bar, temperature at 40 °C, and supercritical fluid flow rate of 12 mL/min. These optimal conditions yielded a 76.3% oil recovery and 836.5 mg/100 g of phytosterol concentration. The oil content in the Kalahari melon seeds as estimated by Soxhlet extraction was around 30.5/100 g. The phytosterol concentration in the oil extracted with SC-CO₂ extraction was 94% higher than that obtained with solvent extraction.     

Optimisation of Olive Paste Expression: Maximizing Yield by Central Composite Design Approach

This work shows results from an optimisation test of olive paste expression. A factorial design was first used to evaluate the effect of the simultaneous variation of the following parameters on the extraction yield: pressure, compaction rate, cake thickness and solids content in the olive paste. It was found that the most important variable for the yield is the rigid solids content, followed by pressure, cake thickness and compaction rate. A central composite design procedure was then applied to identify optimum conditions. The highest extraction yield (983·6 g kg⁻¹) was obtained at low cake thickness (9 mm), high pressure (7598 kPa) and high solids content (450 g kg⁻¹). This extraction yield is much higher than the yield obtained in commercial operations (<850 g kg⁻¹). Furthermore, this result was obtained within a very short time (the time of the extraction phase at constant outflow rate, ie about 1 min), while industrial operations usually last 1 h or longer.     

Ultrasound‐assisted extraction of quercetin from onion solid wastes

The extraction of quercetin with aqueous ethanol solutions from onion solid waste under sonication conditions was investigated using rational experimental design methodologies. It was found that the ethanol concentration (40–80%, v/v) and the temperature (40–60 °C) of extraction are the most influential parameters in the recovery yield, whereas pH (2–6), liquid/solid ratio (30–60 mL g^?1) and extraction time (15–35 min) do not significantly influence the completeness of the extraction. The optimal extraction conditions were determined to be an ethanol percentage of 59% and extraction temperature of 49 °C, yielding a total quercetin content of 11.08 mg per g dry weight of onion solid waste. An empirical relationship between extraction parameters and the extraction yield was suggested and verified.     

Supercritical carbon dioxide extraction of oil and α‐tocopherol from almond seeds

The objective of this study was to extract oil and tocopherols from almond seeds using supercritical carbon dioxide and to compare this extraction with a traditional solvent method. Oil and tocopherol extraction rates were determined as functions of the pressure (350–550 bar), temperature (35–50 °C) and CO₂ flow rate (10–30 kg h⁻¹), using a 10‐l vessel. The effects of matrix particle size on extraction yield were also studied and it was demonstrated that extraction yield is greatly influenced by particle size. Maximum recovery was obtained in the first 2–3 h of extraction at a pressure of 420 bar, a temperature of 50 °C and a flow rate of 30 kg h⁻¹ CO₂. These results suggest that the elevated initial oil and tochopherol solubility is related to the increased proportion of fatty acids in the initial extract. The results were compared with those obtained when hexane/methanol was used as a solvent. Copyright © 2005 Society of Chemical Industry     

Optimization of Supercritical Fluid Extraction of Phenolics from Date Seeds and Characterization of its Antioxidant Activity

Supercritical fluid extraction (SFE) was utilized for the first time to extract phenolics in date seeds. Orthogonal array design (OA₉ (3⁴)) was applied to optimize extraction variables including extraction temperature, extraction pressure, extraction time, and number of extraction. Optimum values of extraction variables were analyzed and number of extractions was found to have a significant effect on total phenolics content (TPC). Optimal SFE conditions for maximum yield of TPC were 50 °C, 350 bar, and two repeated extractions, each for 2 h. Under optimal condition, the TPC was increased to 441.57 mg gallic acid equivalents/100 g fresh weight. Several phenolic compounds were detected in date seeds including chlorogenic acid, rutin, ellagic acid, quercetin, and two unidentified compounds of phenolic acids. In addition, phenolics of date seeds showed a higher antioxidant activity than ascorbic acid at the same concentration in the range of 1.0–8.0 mg/L.     

Supercritical carbon dioxide extraction of pelletized Jalapeño peppers

The effects of process pressure (220–500 bar) and temperature (35–65 °C) on yield and extract quality of pelletized Jalapeño peppers (Capsicum annuum L) treated with supercritical carbon dioxide (ScCO₂) were studied. Compaction was inadequate when using whole air‐dried pepper flakes conditioned to high moisture as raw material, which resulted in high porosity pellets and low bed densities. Thus, reference pellet samples were produced from Jalapeño pepper flakes that were finely ground and conditioned to low moisture. Pressures ≥290 bar did not affect cumulative extraction of reference pellet samples at 45 °C. On the other hand, the extraction rate of reference pellet samples at 360 bar increased with process temperature, as a result of increments in solubility, improvements in mass transfer properties, and/or improvements in solute desorption from the solid matrix. With regard to pretreatment, finely ground pepper samples were extracted in half the time of reference pellets (120 versus 270 min) at 360 bar and 45 °C; increasing sample moisture prior to pelletization increased extraction yield; and decreasing particle size prior to pelletization increased extraction rate slightly. These results suggest that sample moisture is partially co‐extracted by ScCO₂, and that the extraction rate of pelletized Jalapeño peppers is controlled by internal mass transfer mechanisms. Chlorophyllian pigments were removed in the final stages of the extraction process. Furthermore, pigment extraction increased with process pressure at 45 °C, and it increased slightly with process temperature at 360 bar. On the other hand, the concentration of capsaicinoids in extract samples remained constant during ScCO₂ extraction. Copyright © 2003 Society of Chemical Industry     

Supercritical carbon dioxide extraction of astaxanthin and other carotenoids from the microalga Haematococcus pluvialis

Supercritical carbon dioxide extraction of astaxanthin and other carotenoids from Haematococcus pluvialis was carried out, for several experimental conditions, using a semi-continuous apparatus. The microalga was previously freeze-dried and ground with a ball mill. The effects of pressure (200 and 300 bar), temperature (40 and 60 °C), degree of crushing, as well as the use of ethanol as a co-solvent (10%) on the extraction efficiency were assessed. Organic solvent extractions, using acetone, were also carried out in a vortex, on ground cells mixed with very small glass beads. Supercritical extraction from the completely crushed alga was compared with acetone and the highest recovery of carotenoids (92%) was obtained at the pressure of 300 bar and the temperature of 60 °C, using ethanol as a co-solvent.The extraction recovery increased with the pressure at 60 °C. On the other hand, the increase in temperature, at 300 bar, led to a slight improvement. The main carotenoid of Haematococcus pluvialis is the esterified astaxanthin (about 75%). Other carotenoids present are lutein, astaxanthin (free), β-carotene and canthaxanthin. All of them were recovered through supercritical fluid extraction with values higher than 90%, with the exception of canthaxanthin (about 85%), at a pressure of 300 bar and a temperature of 60 °C.     

Supercritical carbon dioxide extraction of lutein from yellow maize (<Emphasis Type="Italic">Zea mays</Emphasis>) kernels: process optimization based on lutein content,antioxidant activity,and ω-6/ω-3 fatty acid ratio

Yellow maize kernels were subjected to supercritical carbon dioxide (SC-CO₂) extraction to obtain a lutein-rich extract with potential nutraceutical properties. SC-CO₂ extraction parameters (pressure and temperature) were optimized by employing a full-factorial (3²) design of experiments and response surface methodology, based on yield of lutein, antioxidant activity, and ω-6/ω-3 fatty acid ratio of the extracts. A Chrastil equation was also developed for predicting the solubility of lutein in SC-CO₂ under different extraction conditions. The optimized extraction condition was obtained at 500 bar, 70 °C for 90 min, at which the extract was found to possess a unique combination of the highest lutein yield (275.00 ± 3.50 μg/g of dry weight), along with a well-balanced ω-6/ω-3 fatty acid ratio (3:1). Moreover, the total phenol content and antioxidant activity were also found to be the highest at this condition. This lutein-rich extract is a promising nutraceutical or dietary supplement in the food industry.     

Enhanced extraction of oleoresin from Piper nigrum by supercritical carbon dioxide using ethanol as a co‐solvent and its bioactivity profile

Pepper oleoresin was extracted using supercritical fluid extraction (SCF) from Piper nigrum berries. The conditions for maximum extraction of piperine were arrived at by calculating the solubility parameters of piperine and carbon dioxide using the Hildebrandt solubility equation. The effect of entrainers such as methanol, ethanol, and acetone was evaluated using theoretical modeling. The results predicted therefrom were validated experimentally. SCF at 250 bar/50 °C/60 min gave maximum relative extraction of 61.7 and 87.61% of oleoresin and piperine, while addition of 30% (vol/wt) ethanol as co‐solvent enhanced the yield to 95.9 and 184.7% under similar conditions of SCF extraction as compared to ethanol extraction for 6 hr. The oleoresins obtained showed comparable antioxidant, anti‐inflammatory, and antimicrobial activities with their respective controls. Hence SCF extraction of pepper using ethanol as a co‐solvent promises a rapid and enhanced recovery of oleoresin and its constituents with a good bioactivity profile.

Practical applications

Although SCF is a promising alternative for extraction of spice oleoresins, high cost of operation limits the use of this technology. In this work, process intensification of SCF extraction of black pepper lead to one step extraction and purification, along with high yield of oleoresin and the principle component piperine, eventually decreasing the cost of production. Thus, the highly concentrated SCF extracted oleoresins can have better replacement value for whole spices and better distribution in food and pharmaceutical sector.     

Optimization of Supercritical Carbon Dioxide Extraction of Bioactive Flavonoid Compounds from Spearmint (<Emphasis Type="Italic">Mentha spicata</Emphasis> L.) Leaves by Using Response Surface Methodology

The bioactive flavonoid compounds of spearmint (Mentha spicata L.) leaves were obtained by using supercritical carbon dioxide (SC-CO₂) extraction. Extraction was carried out according to face-centred central composite design, and independent variables were pressure (100, 200 and 300 bar), temperature (40, 50 and 60 °C) and co-solvent amount (3, 6 and 9 g/min). The extraction process was optimized by using response surface methodology for the highest crude extraction yield of bioactive flavonoid compounds. The optimal conditions were identified as 209.39 bar pressure, 50.00 °C temperature and 7.39 g/min co-solvent amount. The obtained extract under optimum SC-CO₂ condition was analysed by high-performance liquid chromatography. Seven bioactive flavonoids including catechin, epicatechin, rutin, luteolin, myricetin, apigenin and naringenin were identified as major compounds. The results of quantification showed that spearmint leaves are potential source of antioxidant compounds.     

超临界CO2提取辣椒油树脂工艺的研究

以红辣椒粉为原料,采用超临界CO2萃取法提取辣椒油树脂。以辣椒油树脂的收率为评价指标,确定最佳工艺条件为:萃取压力25MPa,萃取温度30℃,萃取时间3h,此条件下辣椒油树脂收率为10.09%±0.29%。对比实验结果显示:超临界CO2法所得的辣椒油树脂的色价为303±5,辣椒素质量浓度为3.7%±0.7%,均明显优于传统的索氏提取法。对超临界CO2法所得的辣椒油树脂进行二次超临界萃取,可将辣椒红色素和辣椒素进行初步分离。     

Application of response surface methodology to optimise supercritical carbon dioxide extraction of oil from rapeseed (Brassica napus L.)

Supercritical CO₂ fluid extraction technology was used to extract oil from rapeseed. Extraction temperature, pressure, time and the sample particle size were selected and optimised by response surface methodology. Conventional solvent extraction was applied as a comparative method. The maximum extraction yield of 32.65 ± 1.01% was achieved at a temperature of 40 °C and a pressure of 345 bar, using an extraction time of 3 h and a 60‐mesh particle size. The chemical compositions of rapeseed oil using esterification method were investigated by GC–MS. The result indicates that the main fatty acids are palmitic acid (2.60%), oleic acid (16.54%), linoleic acid (9.62%), linolenic acid (4.77%), eicosenoic acid (11.20%) and erucic acid (47.09%), respectively. Supercritical fluid extraction has been proved to be an effective technique for extracting oil from Brassica napus L.     

Effect of extraction parameters on the carotenoid recovery from tomato waste

Tomato waste is an important source of natural carotenoids. This study was carried out to assess the extractability of tomato waste carotenoids in different organic solvents and to optimise the extraction parameters (type of solvent, extraction time, temperature and extraction steps) for maximum yield. Among other solvents, we tested a new environmentally friendly one, ethyl lactate, which gave the highest carotenoid yield (243.00 mg kg^?1 dry tomato waste) at 70 °C, compared to acetone (51.90 mg kg^?1), ethyl acetate (46.21 mg kg^?1), hexane (34.45 mg kg^?1) and ethanol (17.57 mg kg^?1). The carotenoid recovery was significantly (P < 0.05) affected by the number of extraction steps and temperature in all solvents. Mathematic equations predicted rather satisfactorily (R² = 0.89–0.93) the rate of carotenoid extraction in the above‐mentioned solvents. Carotenoid concentration increased with time, approaching a quasi‐saturated condition at approximately 30 min of extraction.