Supercritical CO2 Extraction of Oil from Atlantic Mackerel (Scomber scombrus) and Protein Functionality

Supercritical carbon dioxide (SC-CO₂) extraction temperature and pressure for oil removal from freeze-dried, fall Atlantic mackerel muscle were optimized. The effect of extraction conditions on pH and water-binding potential (WBP) of the protein residue was evaluated. For the temperature range (35–55°C) and pressure interval (20.7–34.5 MPa), 34.5 MPa/35°C gave highest oil yield and concentration of ω-3 fatty acids. SC-CO₂ extraction at higher pressure levels caused slight decreases in protein residue pH. WBP of residual proteins was maximal at 1.49g H₂O/g protein for 34.5 MPa/45°C. The high lipid removal and retention of protein functionality in the residue after oil extraction may make such processes useful for future food applications.     

Extraction of fennel (Foeniculum vulgare Mill.) seeds with supercritical CO2: Comparison with hydrodistillation

Ground fennel (Foeniculum vulgare Mill.) seeds, growing wild in Montenegro, were extracted with supercritical CO₂ (SC-CO₂) at a flow rate of 0.2 kg CO₂/h under varying extraction conditions in order to determine yield, composition and organoleptic characteristics of extract. The extracts obtained were compared to fennel seed oil isolated by hydrodistillation. In the SC-CO₂, extracts as well in the hydrodistilled oil, the major compounds were trans-anethole (68.6–75.0%) and (62.0%), methylchavicol (5.09–9.10%) and (4.90%), fenchone (8.40–14.7%) and (20.3%), respectively. With pressure varying from 80 to 150 bar and temperature varying from 40 to 57 °C, it was found that, for the selected herb material, the optimal conditions of SC-CO₂ extraction (high percentage of trans-anethole, with significant content of fenchone and reduced content of methylchavicol and co-extracted cuticular waxes) are: pressure, 100 bar; temperature, 40 °C; extraction time, 120 min. Organoleptic tests confirmed that hydrodistilled oil possessed a less intense fennel seed aroma than extracts obtained by SC-CO₂.     

Extraction of Triglycerides and Phospholipids from Canola with Supercritical Carbon Dioxide and Ethanol

Phospholipids used as emulsifiers were sparingly soluble in supercritical CO₂ (SC-CO₂), but could be recovered with the addition of ethanol as an entrainer. Triglycerides and lipids containing phospholipids were extracted with SC-CO₂ in two subsequent steps from both canola flakes and press cake containing 0 and 5% ethanol, respectively. 70°C, 62.0 MPa and addition of ethanol at an initial level of 5% gave maximum yield of lipids. TLC showed the presence of phospholipids in SC-CO₂-ethanol extracts. SC-CO₂ extracts of flakes did not contain long chain fatty acids (C20:0, C22:0, C22:1), but they were extracted when ethanol was added to flakes and when press cake was the raw material.     

Extraction of boldo (Peumus boldus M.) leaves with supercritical CO2 and hot pressurized water

High-activity fractions in boldo leaves were extracted with supercritical CO₂ (SC-CO₂) and hot pressurized water (HPW). Total yield after 3 h of extraction (0.6–3.5%) in low-pressure SC-CO₂ experiments increased with process pressure (60–150 bar) and decreased with temperature (30–60 °C), as expected. The extract obtained with SC-CO₂ at 50 °C and 90 bar contained approximately 50% of essential oil components. In higher pressure experiments with solvent mixtures, the yield increased with pressure (300–450 bar) and modifier concentration (2–10% ethanol), ranging 0.14–1.95 ppm for the alkaloid boldine and 1.8–4.8% for total solids following 1.5 h treatment at 50 °C. Boldine recovery was solubility-controlled, reaching 7.4 ppm after 7-h extraction at 450 bar and 50 °C using an ethanol–SC-CO₂ mixture (5% co-solvent). Boldine solubility and yield decreased when using pure CO₂ at higher pressure (600 bar, 50 °C). The extract yield after 3 h batch-wise HPW extraction increased from 36.9% at 100 °C to 53.2% at 125 °C, and then decreased as temperature was increased to 175 °C. Boldine yield decreased from 26.8 ppm at 100 °C to 0.7 ppm at 125 °C, and was negligible at ⩾150 °C. The essential oil yield increased to a maximum at 110 °C and was negligible at ⩾150 °C also. The ranking of antioxidant potency of various extracts was as follows: HPW at 110 °C > methanol (soxhlet extraction) ≫ high-pressure SC-CO₂ with or without polar co-solvent > low-pressure SC-CO₂.     

Supercritical CO2 Extraction of Oil and Residual Proteins from Atlantic Mackerel (Scomber scombrus) as Affected by Moisture Content

Lipid composition of supercritical CO₂ (SC-CO₂) extracts, residual oil in muscle and changes in sarcoplasmic proteins after extraction of Atlantic mackerel were characterized. Dehydration of the muscle to 10.2% (w/w) resulted in high oil yield with minimum changes in protein content and composition. Sarcoplasmic protein content of fish muscle following SC-CO₂ treatment was lower than that of original muscles at all moisture levels (3.8–64%, w/w). Analysis of sarcoplasmic proteins by capillary electrophoresis indicated aggregation of low molecular weight proteins during SC-CO₂ extraction. SC-CO₂-extracted muscle also had lighter color than original samples. The SC-CO₂ extraction showed potential to provide high quality oil and protein meal.     

Temperature and pressure effects on supercritical carbon dioxide extraction of n-3 fatty acids from red seaweed

Lipids were extracted with supercritical carbon dioxide (SC-CO₂) from a subtropical red seaweed (Hypnea charoides) within the temperature range 40–50°C and the pressure range 24.1–37.9 MPa. In general, the extraction rates of algal lipids increased with pressure and temperature except when the pressure was at 24.1 MPa. The combined effect of pressure and temperature on the solubility of individual n-3 fatty acids in the SC-CO₂ varied with its carbon chain length. The concentrations of C₁₈, C₂₀ and C₂₂ n-3 fatty acids, extracted under different pressure and temperature conditions, were significantly different (p<0.05). Proportions of total polyunsaturated fatty acids increased significantly (p<0.05) and proportions of total saturated fatty acids decreased significantly (p<0.05) with increasing pressure as shown by the saturated/unsaturated and saturated/polyunsaturated ratios.     

Phytosterol Enrichment of Rice Bran Oil by a Supercritical Carbon Dioxide Fractionation Technique

Supercritical carbon dioxide (SC–CO₂) fractionation technique was evaluated as an alternative process for reducing the free‐fatty‐acid (FFA) content and minimizing the phytosterol loss of rice bran oil (RBO) during the process. The effects of pressure (20.5 to 32.0 MPa) and temperature (45 to 80 °C) for isothermal operation of the column on the composition of the resultant fractions were examined. Low‐pressure and high‐temperature conditions were found to be favorable for minimizing triglycerides (TG) and phytosterol losses during the FFA removal from crude RBO. Rice bran oil fractions with < 1% FFA, about 95% TG, and 0.35% free sterol with 1.8% oryzanol content could be obtained utilizing the described SC–CO₂ fractionation technique.     

Effects of supercritical CO2 fluid parameters on chemical composition and yield of carotenoids extracted from pumpkin

Pumpkin is a traditional food that is grown extensively worldwide and is believed to be beneficial to human health due to its high contents of carotenoids. The carotenoids in pumpkin were extracted by organic solvents and by supercritical carbon dioxide (SC-CO₂), and then they were identified, quantified, and compared. β-carotene (31 to 40 g per 100 g of total carotenoids) was the predominate carotenoid in pumpkin. Lutein and lycopene contents were much higher in SC-CO₂ extracts than those in organic solvent extract. Cis-β-carotene increased by more than two times in the SC-CO₂ extracts, even at a relatively low temperature of 40 °C, over those in the solvent extracts, indicating both enhanced solubility and isomerization from trans- to cis-β-carotene. The influences of modifier (10 mL/100 mL), temperature (40-70 °C), and pressure (25-35 MPa) of SC-CO₂ extraction on the change of carotenoid yields were also investigated. The highest yield (109.6 μg/g) was obtained at 70 °C and 35 MPa, with a 73.7% recovery. Selective extraction could be achieved by adjusting the temperature and pressure. Higher proportions of all-trans-β-carotene extracts were achieved at 40 °C under both 25 MPa and 35 MPa conditions. In order to extract more cis-isomers, a higher temperature of 70 °C was preferred.     

Preparation and Evaluation of Supercritical Carbon Dioxide Defatted Soybean Flakes

Full-fat soybean flakes were extracted with supercritical carbon dioxide (SC-CO₂) at pressures of 10,600–12,400 psi, temperatures from 80–100°C, and moisture levels of 5–13.5%. Conditions could be selected to produce defatted soybean meals with nitrogen solubility indices greater than 70% and flavor scores greater than 6.5 on a scale of 1 to 10 (1 = strong and 10 = bland). The usual grassy-beany and bitter flavors of hexane-defatted soybean flours were only minimally detectable in the optimally SC-CO₂-extracted materials. Bland, defatted soybean meal prepared by SC-CO₂ extraction was further processed into high-quality protein concentrates and isolates that were stable when stored under adverse conditions.     

Supercritical CO2 Extraction of Annatto (Bixa orellana) Pigments and Some Characteristics of the Color Extracts

Supercritical CO₂ (SC-CO₂) was used to extract natural food colors from Annatto (Bixa orellana) seeds with different pressures and temperatures. Results from the reverse thin-layer chromatographic separation and GC/MS revealed that SC-CO₂ extracts were composed mainly of bixin, geranylgeraniol and norbixin. Differences in absolute values of solubility parameters (SPD) between these main compounds and SC-CO₂ indicated bixin was more easily extracted than norbixin under conditions used. A higher yield of total pigments was obtained at extraction pressure above 310 bar than at 210 bar and 50°C.     

Proximate composition and extraction of carotenoids and lipids from Brazilian redspotted shrimp waste (Farfantepenaeus paulensis)

The chemical composition of redspotted shrimp (Penaeus paulensis) waste was investigated. The shrimp waste (freeze-dried heads, shells and tails) was found to have high protein (49% d.w.) and ash (27% d.w.) contents, but a low lipid content (4.9% d.w.) although the latter was higher than those found in other kinds of shrimp captured in Brazil. The fatty acid compositions showed that the lipids had a high content of unsaturated fatty acids, mainly EPA (C20:5; n-3) and DHA (C22:6; n-3). In order to establish an efficient and environmentally friendly recovery process for the astaxanthin (principal carotenoid and antioxidant present in the waste), the following processes were examined: traditional solvent extraction (TSE), super-critical fluid extraction (SC-CO₂) and super-critical fluid extraction with co-solvent (SC-CO₂ + ethanol). The temperature and pressure conditions for all the SC-CO₂ extractions were 50 °C and 30.0 MPa. The results showed that the mixture of 60% (v/v) n-hexane:isopropyl alcohol gave the highest (53 mg/kg waste) carotenoid extraction yield as compared to acetone, SC-CO₂ and SC-CO₂ + ethanol. The SC-CO₂ showed the lowest extraction yield of astaxanthin, but the addition of the entrainer (10% w/w) produced an important effect, increasing the astaxanthin extraction to values of 57.9%, similar to extraction with acetone (63.3%).     

Extraction behaviors of caffeine and chlorophylls in supercritical decaffeination of green tea leaves

The decaffeination of green tea using supercritical carbon dioxide (SC-CO₂) was optimized by response surface methodology (RSM) for the maximal removal of caffeine, and the coextration of chlorophylls was also monitored during decaffeination. The experimental conditions for the SC-CO₂ extraction of caffeine were set up according to the Box-Behnken design of RSM. The relationships between the extraction yield of caffeine and various parameters used for the SC-CO₂ extraction such as pressure, temperature and concentration of ethanol were studied at a fixed CO₂ flow rate. The extraction yields of caffeine and total chlorophyll were significantly influenced by extraction pressure, temperature and concentration of cosolvent, and their extraction yields behaved almost in parallel at different extraction conditions that were obtained by varying pressure, temperature and ethanol cosolvent concentration. At the optimal decaffeination conditions such as 3.0 g of 95% (v/v) ethanol cosolvent per 100 g of CO₂, 23 MPa, 63 °C and an extraction duration of 120 min for 10 g of green tea leaves, the extraction yields for caffeine and catechins were 96.60% (w/w) and 40.61% (w/w), respectively, and the substantial coextraction of total chlorophyll (43.09% of the total amount) was also observed during the decaffeination process.     

Extraction of oil from tiger nut (Cyperus esculentus L.) with supercritical carbon dioxide (SC-CO2)

Supercritical carbon dioxide (SC-CO₂) was used to extract oil from tiger nuts and the physicochemical properties and the impact of extraction conditions [i.e., temperature (40 °C–80 °C), pressure (20–40 MPa) and time (60–360 min)] on the oil yield were studied. The response surface analysis results revealed that the oil yield was significantly (P < 0.05) influenced by the main effect of the extraction pressure, extraction time and their quadratic effects respectively. However, the interaction between the extraction temperature and time had no significant (P > 0.05) effect on the oil yield. The highest oil yield was 26.28 g/100 g sample after 210 min of extraction time at 30.25 MPa and 60 °C respectively. The fatty acid composition of oils obtained by SC-CO₂ and Soxhlet showed marked variation. Also, the fatty acid composition varied depending on the operating conditions. The viscosity of the oil decreased with the increase in temperature.     

Extraction of alkylresorcinols from wheat bran with supercritical CO2

The supercritical fluid extraction (SFE) of wheat bran alkylresorcinols has been studied. Extractions were carried out at 40.0 MPa. The effect of particle size, static extraction pretreatment with supercritical CO₂ (SC-CO₂) and extraction temperature on the extraction kinetics was investigated. The extraction yield increased as the particle size decreased and with temperature. Extraction curves present a faster and linear initial extraction period followed by a slower extraction period. Based on these results the approximate mathematical model of Sovová was successfully applied to describe the extraction curves. The total content of alkylresorcinols was determined and compared with the alkylresorcinol content obtained by conventional organic solvent extraction. Due to the amphiphilic nature of these resorcinolic lipids, the extraction yield was higher for polar organic solvents than for SC-CO₂. Characterization of supercritical extracts was also performed by determining the fatty acid composition and antioxidant activity.     

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.     

Effects of supercritical carbon dioxide extraction parameters on virgin coconut oil yield and medium-chain triglyceride content

The extraction of coconut oil has been performed using supercritical carbon dioxide (SC-CO₂). The extractions were performed at pressure and temperature ranges of 20.7–34.5 MPa and 40–80 °C, respectively. It was observed that almost all (more than 99%) of the total oil could be extracted. Response surface methodology (RSM) was applied to evaluate the effects of the parameters (pressure, temperature and CO₂ consumption) on the extraction yield and medium-chain triglycerides (MCTs), in terms of the fatty acid content in the extracted oil. A correlation was established with p-values for both responses significant at the 95% confidence level.     

Extraction of ewe's milk cream with supercritical carbon dioxide

The extraction of ewe's milk cream by supercritical carbon dioxide in the pressure range 9–30 MPa (90–300 bar) and at temperatures of 40 °C and 50 °C was studied. The solubility of total fat increased with pressure at both temperatures until a plateau was reached. The extraction of cholesterol also increased with pressure until a plateau was reached and it was higher at 50 °C than at 40 °C when the pressure was ≥15 MPa (150 bar). The triglyceride composition of each extract, determined by GC, showed that extracts obtained at lower pressures were enriched in short-chain triglycerides and their concentration decreased as the pressure increased. In the other hand, long-chain triglycerides were enriched in the extracts obtained at higher pressures and their concentration rose with increasing pressure.     

Effects of Moisture and pH on Supercritical Fluid Extraction of Cocoa Butter

The effects of moisture content and alkali treatment on cocoa butter extraction using supercritical fluid were studied. Ground cocoa nibs were examined at moisture contents of 1.95 %, 3.91 %, 5.87 %, 9.79 % and 17.64 % and the pH of the cocoa liquor was maintained at 5.0–5.9, 6.8–7.2 and 7.5–7.9. Cocoa butter was successfully extracted, using supercritical carbon dioxide (SC-CO₂) for the moisture content study and SC-CO₂ with 25 % ethanol as a cosolvent for the pH-level alkali treatment study, at 35 MPa, 60 °C and 2 ml/min. The results showed that increases in moisture content and pH level significantly (p?<?0.05) increase the yield efficiency. A moisture content of 9.79 % and pH-alkali treatment at 7.5–7.9 produced the highest yield (60.36 % and 73.70 % at 20 and 18 h extraction time, respectively). Triglycerides (TG) and fatty acids (FAs) were similar to those found in cocoa butter obtained using the Soxhlet method. Saturated and short-chain TG and FA constituents were more soluble than unsaturated and long-chain constituents.     

Triglyceride Content of Supercritical Carbon Dioxide Extracted Fractions of Beef Fat

Beef fat was fractionated using supercritical carbon dioxide at 40°C and pressures from 10.3–27.6 MPa. Extractions followed by one or two stage separation were collected at atmospheric pressure and ambient temperature. Triglyceride analysis of extracts using HPLC and evaporative light scattering detection resolved 15 major peaks. Triglyceride content (mg/g extract) was influenced by extraction conditions. Extraction at 27.6 MPa and separation at 20.7 MPa resulted in highest triglyceride concentration, while 13.8 MPa resulted in the lowest. Saturated and monounsaturated triglycerides were selectively extracted based on solvent density and molecular weight. Little selectivity of polyunsaturated triglycerides was observed for fractionating beef fat.     

Reduction of Warmed-Over Flavor Volatiles from Freeze-Dried Lean by Supercritical CO2 Extraction

Supercritical carbon dioxide (SC-CO₂) was used to extract warmed-over flavor (WOF) volatiles from cooked, freeze-dried beef at 40°C and pressures of 10.3 MPa or 30 MPa after 2 days storage. WOF markers, hexanal, heptanal, octanal, nonanal, and 2,3-octanedione, were identified in the volatiles profile of precooked beef by dynamic headspace extraction and gas chromatography-mass spectrometry before and after CO₂ extraction. TBARS and levels of WOF markers increased over 2 days storage. There was a reduction in WOF markers at both extraction pressures. The higher pressure led to greater reduction of WOF markers (e.g., hexanal: 73.5%) than the lower pressure (e.g., hexanal: 60.3%), notably for heptanal and nonanal. SC-CO₂ may be applicable for reducing WOF volatiles from precooked meats.