Characterisation of oleoresins extracted from tomato waste by liquid and supercritical carbon dioxide

Tomato waste is characterised by high amounts of bioactive compounds, such as carotenoids, polyphenols and essential fatty acids. In this work, oleoresins were produced from tomato waste (skins + seeds) and skins using carbon dioxide under liquid and supercritical conditions. The use of ethanol as a co-solvent was also evaluated. Compositions of the oleoresins were analysed and compared to oleoresin obtained by means of an organic solvent, which was used as the control. Oleoresin extraction from the waste by liquid and supercritical CO₂ provided the highest yields (12.5%–12.9%). The extracts obtained from the skins with supercritical CO₂ without ethanol had the highest content of α- and γ-tocopherols (80 and 575 mg/100 g oleoresin, respectively), while lycopene and β-carotene were found at 205 and 75 mg/100 g oleoresin, respectively. The highest quantity of polyphenols (9305 mg GAE/100 g oleoresin) was found in the oleoresin extracted from skin by supercritical CO₂ with ethanol. All oleoresins were characterised by a high antioxidant activity, which improved with the synergy of carotenoids, tocopherols and polyphenols.     

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     

Effect of supercritical CO2 extraction process parameters on oil yield and pigment content from by‐product hemp cake

This research gives an insight into the possibility of exploiting the one of the food industry's by‐products – pressed hemp cake. The complete recovery of oil from pressed hemp cake was achieved. Residual oil that remained in cake after pressing was extracted with supercritical CO₂ by applying different process parameters. Optimal extraction conditions were determined using response surface methodology. Total pigment contents of the oils obtained were determined. Extraction pressure had the most significant influence on yield and pigment content of extracted hemp cake oil. Depending on the pressure, the chlorophyll a content ranged from 101.11 to 378.28 mg kg^?1 and chlorophyll b from 65.14 to 189.78 mg kg^?1, while total carotene content was in the range from 33.58 to 132.67 mg kg^?1. The remaining oil in pressed hemp cake after supercritical CO₂ extraction was determined to be 0.56 ± 0.08% and the defatted cake was rich in proteins and fibre.     

Effect of Extraction Method on the Oxidative Stability of Camelina Seed Oil Studied by Differential Scanning Calorimetry

Camelina seed is a new alternative omega‐3 source attracting growing interest. However, it is susceptible to oxidation due to its high omega‐3 content. The objective of this study was to improve the oxidative stability of the camelina seed oil at the extraction stage in order to eliminate or minimize the use of additive antioxidants. Camelina seed oil extracts were enriched in terms of natural antioxidants using ethanol‐modified supercritical carbon dioxide (SC‐CO₂) extraction. Oxidative stability of the camelina seed oils extracted by ethanol modified SC‐CO₂ was studied by differential scanning calorimeter (DSC), and compared with cold press, hexane, and SC‐CO₂ methods. Nonisothermal oxidation kinetics of the oils obtained by different extraction methods were studied by DSC at varying heating rates (2.5, 5, 10, and 15 ° C/min). Increasing ethanol level in the ethanol‐modified SC‐CO₂ increased the oxidative stability. Based on oxidation onset temperatures (T_on), SC‐CO₂ containing 10% ethanol yielded the most stable oil. Oxidative stability depended on the type and content of the polar fractions, namely, phenolic compounds and phospholipids. Phenolic compounds acted as natural antioxidants, whereas increased phospholipid contents decreased the stability. Study has shown that the oxidative stability of the oils can be improved at the extraction stage and this may eliminate the need for additive antioxidants.     

Supercritical Carbon Dioxide Extraction of Valuable Compounds from Citrus junos Seed

Extraction of Citrus junos seed was carried out at temperatures of 40–70 °C, pressures of 20–50 MPa, and CO₂ flow rate of 3 ml/min with supercritical carbon dioxide to obtain the valuable compounds. Seed oil was also extracted by using Soxhlet extraction with hexane as the solvent during 360 min for comparison with the efficiency of supercritical carbon dioxide extraction. Gas chromatography–mass spectrometry (GC–MS) was used to analyze the components present in the seed oil and Gas chromatography-flame ionization detector (GC-FID) was used to quantify their amounts. Among the conditions studied, the highest extraction yield was obtained at higher pressure and temperature (50 MPa and 70 °C). The extraction yield was about 29.5% of the seed, which was almost comparable to that of hexane Soxhlet extraction (33.8%). The results of the GC–MS analyses showed that the seed oil extracted contained N-methylanthranyl acid methyl, fatty acids (such as palmitic, stearic, oleic, linoleic, and linolenic acid), and physiologically active substances of β-sitosterol and squalene.     

Chemical Properties and Oxidative Stability of Perilla Oils Obtained From Roasted Perilla Seeds As Affected by Extraction Methods

Abstract: The chemical properties and oxidative stability of perilla oils obtained from roasted perilla seeds as affected by extraction methods (supercritical carbon dioxide [SC‐CO₂], mechanical press, and solvent extraction) were studied. The SC‐CO₂ extraction at 420 bar and 50 °C and hexane extraction showed significantly higher oil yield than mechanical press extraction (P < 0.05). The fatty acid compositions in the oils were virtually identical regardless of the extraction methods. The contents of tocopherol, sterol, policosanol, and phosphorus in the perilla oils greatly varied with the extraction methods. The SC‐CO₂‐extracted perilla oils contained significantly higher contents of tocopherols, sterols, and policosanols than the mechanical press‐extracted and hexane‐extracted oils (P < 0.05). The SC‐CO₂‐extracted oil showed the greatly lower oxidative stability than press‐extracted and hexane‐extracted oils during the storage in the oven under dark at 60 °C. However, the photooxidative stabilities of the oils were not considerably different with extraction methods.     

Supercritical CO2 extraction optimization of pomegranate (Punica granatum L.) seed oil using response surface methodology

This study examined extraction of pomegranate seed oil by using supercritical carbon dioxide. Response surface methodology was used to evaluate the effects of the process parameters, namely extraction pressure, temperature and CO₂ flow rate on the yield of pomegranate seed oil. The extraction parameters were optimized with a central composite design experiment. The linear term of pressure, followed by the linear term of CO₂ flow rate, the quadratic terms of pressure, temperature and CO₂ flow rate and the interactions between pressure and temperature, as well as CO₂ flow rate and temperature, had significant effects on the oil yield (p < 0.05). Maximum yield of pomegranate seed oil from the mathematical model was predicted to be 156.3 g/kg dry basis under the condition of pressure 37.9 MPa and temperature 47.0 °C with CO₂ flow rate of 21.3 L/h. The fatty acid composition and the tocopherols' content of pomegranate seed oil extracted using supercritical CO₂ were compared with those obtained by Soxhlet method. Minor difference was found in the fatty acid composition of the oils extracted by the two methods. The content of total tocopherols was about 14% higher in the oil extracted with supercritical CO₂ than that obtained by Soxhlet extraction.     

Breaking the cells of rape bee pollen and consecutive extraction of functional oil with supercritical carbon dioxide

Supercritical carbon dioxide was applied to break the cell wall of rape bee pollen and consecutively extract lyzed bee pollen oil. The supercritical CO₂ rapid depressurization was carried out on the bee pollen. The conditions of consecutive extraction of lyzed bee pollen oil were optimized using response surface methodology and performed at the range of pressure 13.2–46.8 MPa, temperature 33.2–66.8 °C and CO₂ flow rate 6.6–23.4 L/h. Scanning electron microscopy studies revealed that supercritical CO₂ treatment was an effective way to break cell of rape bee pollen and higher CO₂ pressure was found to be more effective. The extraction pressure, temperature and CO₂ flow rate significantly affected the yield of lyzed bee pollen oil in supercritical CO₂ extraction. Optimum oil yield was obtained as 5.98 g/100 g dry pollen at the following predicted conditions: extracted at 39.2 MPa and 54.7 °C with CO₂ flow rate of 17.1 L/h after bee pollen was treated with supercritical CO₂ at 45 MPa for 10 min and then depressurizing. Polyunsaturated fatty acids were the predominant fatty acids in the extracted oil, indicating its potential in the nutraceutical industry.Industrial relevanceThe application of supercritical CO₂ technology in food industry has received much attention in recent years. This study investigates the feasibility of breaking pollen cell wall by supercritical CO₂. The procedure is under low temperature with short time. From an industrial point of view, it is a promising method for breaking bee pollen cell wall. The optimum parameter of supercritical CO₂ extraction of functional pollen oil simultaneously obtained from the process may also be attractive to the food and nutraceutical industries.     

Extraction of soybean isoflavones from soybean meal with aqueous methanol modified supercritical carbon dioxide

The effects of modifier composition in terms of methanol content in water, modifier concentration, meal particle size and extraction conditions (temperature, pressure and CO₂ flow rate) on isoflavones recovery from soybean meal by supercritical carbon dioxide (SC–CO₂) extraction were investigated. The highest isoflavones recovery attained was 87.3%, at 40 °C and 50 MPa, using CO₂ flow rate of 9.80 kg/h containing a modifier 7.8 mass% of 80% (v/v) aqueous methanol. Using different modifier concentrations (60–100% methanol) at 50 MPa and 40 °C, it was shown that 80% methanol was optimum for isoflavones extraction. In addition, isoflavones recovery increased with the modifier content in SC–CO₂ up to 10.2%. The optimal particle size was 20–30 mesh with bigger and smaller particles resulting in lower isoflavones recovery. The results showed that increasing the temperature from 40 to 70 °C drastically reduced isoflavones recovery at 50 MPa. The higher the extraction pressure, the higher was the isoflavones recovery. The extraction rate increased with CO₂ flow rate but the percentage recovery was more or less the same.     

Enrichment of tocols from rice germ oil using supercritical carbon dioxide

An efficient process was developed for enrichment of tocols from rice germ oil (RGO) using supercritical carbon dioxide (SC‐CO₂). Tocols were efficiently enriched in residue by removal of fatty acid methyl ester from the esterified RGO using SC‐CO₂. The enrichment of tocols was carried out at an operating pressure of 12.4–15.8 MPa, an operating temperature of 40–60 °C and a carbon dioxide flow rate of 5.0 L min^?1. The combination of 13.8 MPa pressure and 60 °C temperature was selected as the most suitable for efficient enrichment of tocols. The level of tocols (1270 mg/100 g) in the residue obtained at these operating conditions was six times higher than the tocols level (192 mg/100 g) of the starting material, namely esterified RGO. There were no significant differences in relative percentages of tocols homologues between esterified RGO and the residue obtained by SC‐CO₂ extraction.     

Effects of parameters on yield for sub-critical R134a extraction of palm oil

Extraction of palm oil from its palm mesocarp using sub-critical 1,1,1,2-tetrafluoroethane (R134a) as an alternative solvent to supercritical CO₂ was studied. The effects of pressure, temperature, flowrate and sample pre-treatment method on extraction yield were examined. Dynamic method was used to determine palm oil solubility at flowrate between 0.5 and 5.0 ml/min. Extraction was performed at pressures between 45 and 100 bar which was lower than those required by CO₂ solvent, and at temperatures between 40° and 80 °C. The results show that extraction yields using R134a increased with pressure and temperature, and that temperature effect (p-value = 0.0000) on palm oil solubility prevailed over that of pressure (p-value = 0.0087). The maximum yield of 66.06 w/w% was obtained at 100 bar and 80 °C which was the best pressure and temperature. Substantial oil yields at relatively lower pressure proved that sub-critical R134a is a viable alternative to CO₂ for extraction of palm oil.     

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

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

Effect of fruit ripeness and method of fruit drying on the extractability of avocado oil with hexane and supercritical carbon dioxide

BACKGROUND: Oil yield from avocado fruit may be influenced by fruit pre‐treatment and extraction method. Unripe and ripe avocado fruit pieces were deep‐frozen at ? 20 °C and either freeze‐dried or oven‐dried (80 °C). Oil yield from these samples was determined after extraction with hexane and supercritical carbon dioxide (SC‐CO₂). The fruit samples were examined using scanning electron microscopy before and after oil extraction. RESULTS: Average oil yield from ripe fruit (freeze‐dried and oven‐dried combined) was 72 g kg^?1 higher than from unripe fruit for SC‐CO₂ extracts and 61 g kg^?1 higher for hexane extracts. This may be due to enzymatic degradation of parenchyma cell walls during ripening, thus making the oil more available for extraction. Freeze‐dried samples had a mean oil yield 55 g kg^?1 greater than oven‐dried samples for SC‐CO₂ extracts and 31 g kg^?1 higher for hexane extracts. However, oil yields from ripe fruit (freeze‐dried and oven‐dried) subjected to hexane extraction were not significantly different. All hexane extracts combined had a mean oil yield 93 g kg^?1 higher than SC‐CO₂ extracts. CONCLUSION: SC‐CO₂ may be more selective and may create paths of least resistance through the plant material. Hexane, on the other hand, is less selective and permeates the whole plant material, leading to more complete extraction and higher oil yields under the experimental conditions. Copyright © 2007 Society of Chemical Industry     

Composition and antioxidative activities of supercritical CO2-extracted oils from seeds and soft parts of northern berries

The present study investigated the composition and the antioxidative activities of oils from the seeds and the soft parts of a range of northern berries extracted by supercritical CO₂. The seed oils of the species of Rubus, Vaccinium, Empetrum, Fragaria and Hippophaë were rich in linoleic (18:2n-6, 34-55% of total fatty acids) and ??-linolenic (18:3n-3, 29-45% of total) acids with n-6:n-3 ratios of 1:1-1:2. The seed oils of the species Ribes contained, in addition to linoleic and ??-linolenic acids, ??-linolenic (18:3n-6) and stearidonic (18:3n-4) acids. In seed oils from European rowanberry (Sorbus aucuparia L.) and snowball berry (Viburnum opulus L.), linoleic and oleic (18:1n-9) acids together exceeded 90% of the total fatty acids. The sea buckthorn (SB) pulp oil had palmitoleic (16:1n-7), palmitic (16:0) and oleic acids as the major fatty acids. The SB pulp oil and snowball berry seed oil were rich in ??-tocopherol (120 and 110 mg/100 g oil, respectively), whereas raspberry seed oil contained a high level of ??-tocopherol (320 mg/100 g oil). Seed oils of cranberry (180 mg/100 g oil), Arctic cranberry (190 mg/100 g oil) and lingonberry (120 mg/100 g oil) are rich sources of ??-tocotrienol. The berry seed oils and the SB pulp oil showed varying peroxyl radical scavenging efficacies (300-2300 ??mol ??-tocopherol equivalent per 100 g oil) and inhibitory effects on perioxidation of microsomal lipids (250-1200 ??mol trolox equivalent per 100 g oil) in vitro. The peroxyl radical scavenging activity positively correlated with the total content of tocopherols and tocotrienols of the oils (r = 0.875, P = 0.001). The SB seed oil and pulp oil were active in scavenging superoxide anions produced by xanthine-xanthine oxidase system and inhibited Cu²⁺-induced LDL oxidation in vitro. The SB oils also protected purified DNA and rat liver homogenate from UV-induced DNA oxidation in vitro. The current research suggests potential of supercritical CO₂-extracted oils from northern berries as nutraceuticals and ingredients of functional foods.     

Supercritical CO2 cell breaking extraction of Lycium barbarum seed oil and determination of its chemical composition by HPLC/APCI/MS and antioxidant activity

The extraction parameters for oil extraction from Lycium barbarum seed including extraction pressure, temperature and time were optimized using an orthogonal test design. The optimum conditions for supercritical CO₂ extraction were as follows: extraction pressure, 30 MPa; extraction temperature, 45 °C; dynamic extraction time, 60 min; CO₂ flow, 25 kg/h. The oil yield under the conditions proposed was 19.28 g/100 g. The effect of cell wall breakage pretreatment was investigated by supercritical CO₂ rapid depressurization, and results indicated this pretreatment could result in a rapid and efficient extraction. A sensitive fluorescent reagent 2-(11H-benzo[a]carbazol-11-yl) ethyl 4-methylbenzenesulfonate (BCETS) was utilized as pre-column labeling regent to determine fatty acids (FA) from Lycium barbarum seed oils obtained by different extraction methods. The main FA were: C18:2, C18:1, C16, C20:6, C18:3, and C20. The oil from L. barbarum seed exhibited excellent antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl（DPPH）radical scavenging assay and β-carotene bleaching test, and its antioxidant activity compared well with the references ascorbic acid and α- tocopherol.     

Apparent solubility of lycopene and β-carotene in supercritical CO2, CO2 + ethanol and CO2 + canola oil using dynamic extraction of tomatoes

Lycopene and β-carotene were extracted from freeze-dried tomatoes (skin + pulp) with pure SC CO₂ and SC CO₂ + 5% w/w co-solvent at 40 °C, 400 bar and flow rates of 0.5 and 1.2 L/min. The apparent solubility of lycopene and β-carotene in the multicomponent complex system was determined from dynamic extraction experiments using a laboratory-scale supercritical extraction system. Solubility of pure lycopene and β-carotene in SC CO₂ (binary system) was reported in the literature to be of the order of 10⁻⁶ mole fraction. The apparent solubility of lycopene extracted from tomatoes with SC CO₂ (multicomponent complex system) under the same conditions was almost one order of magnitude smaller. The apparent solubility obtained using oil as a co-solvent was higher than that obtained with ethanol as a co-solvent or pure SC CO₂. The differences in solubility are mainly due to the polarity of the co-solvent and the impact of the tomato matrix in the multicomponent complex system.     

Application of response surface methodology to optimise supercritical carbon dioxide extraction of essential oil from Cyperus rotundus Linn.

Supercritical fluid extraction with carbon dioxide (SC-CO₂ extraction) was performed to isolate essential oils from the rhizomes of Cyperus rotundus Linn. Effects of temperature, pressure, extraction time, and CO₂ flow rate on the yield of essential oils were investigated by response surface methodology (RSM). The oil yield was represented by a second-order polynomial model using central composite rotatable design (CCRD). The oil yield increased significantly with pressure (p < 0.0001) and CO₂ flow rate (p < 0.01). The maximum oil yield from the response surface equation was predicted to be 1.82% using an extraction temperature of 37.6 °C, pressure of 294.4 bar, extraction time of 119.8 min, and CO₂ flow rate of 20.9 L/h.     

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.     

Distribution of microbes in supercritical CO2 extraction of sea buckthorn (Hippopha? rhamnoides) oils

 The distribution of vegetative microbial cells and their spores in a supercritical CO₂ extraction process was studied. The seed and flesh/skin fractions of the press residue of sea buckthorn berries (Hippopha? rhamnoides) from a juice factory were used as raw materials. A pilot-scale extraction plant was operated at 30 MPa at temperatures of 40 and 60°C. The number of yeasts, moulds and bacteria in the pulp/skin fraction, in the extraction residues, in the extracted oils as well as in the water phases separated from the extracted oils was estimated by the spread plate technique. The microbial content of the flesh/skin material was increased in some extractions by the addition of bacterial spores. In general, the extraction process led to a decrease in the bacterial count of the extracted material, whereas no microbial growth was detected in the oils extracted or in the water phases separated from them. Neither yeasts nor moulds were found in any samples after the extraction process. The microbial status of seed oil and flesh/skin oil obtained by industrial-scale CO₂ extraction at 40°C and at 30 MPa before and after gelatine encapsulation remained unchanged. This proves that supercritical CO₂ can be used to manufacture edible oil products free of living micro-organisms and their spores. Received: 14 May 1996     

Continuous flow nonthermal CO2 processing: the lethal effects of subcritical and supercritical CO2 on total microbial populations and bacterial spores in raw milk

The effect of pressurized (<50 MPa) CO₂ as a nonthermal process for bacterial reduction in raw skim milk was examined using a unique pressurized continuous flow system. The lethal effects of subcritical and super-critical CO₂ applied at different temperatures and pressures toward total native psychrotrophic microbial populations, total inoculated Pseudomonas fluorescens, and total inoculated spore populations were studied and compared. Pressures between 10.3 and 48.3 MPa; temperatures of 15, 30, 35, and 40°C; and CO₂ concentrations of 0, 3, 66, and 132 g/kg of milk were studied. For both native populations and inoculated P. fluorescens, greater total microbial lethality was observed under supercritical CO₂ conditions than under subcritical CO₂ conditions. At 30°C, there was no effect on total microbial lethality of increasing pressure up to 20.7 MPa with either 66 or 132 g/kg of CO₂; at 35°C, there was a positive relationship between pressure and lethality at CO₂ levels of 132 g/kg, but no relationship at 66 g/kg of CO₂. For total microbial populations and P. fluorescens, CO₂ applied at 132 g/kg at 30°C and pressures of 10.3 to 20.7 MPa resulted in an average standard plate count reduction of 3.81 and 2.93 log, respectively; at 35°C and 20.7 MPa, maximum reductions achieved were 5.36 and 5.02 log, respectively. For both total microbial populations and inoculated P. fluorescens, CO₂ exhibited a greater overall lethal effect at 132 g/kg than at 66 g/kg and a greater effect at 35°C than at 30°C. At 24.1 and 48.3 MPa and 40°C, microbial lethality in raw aged milk treated with 3 g/kg of CO₂ was not significantly different than that observed for uncarbonated milk; lethality achieved in milk treated with 132 g/kg of CO₂ was significantly higher than that achieved in these 2 low-level CO₂ treatments. No treatment studied had any significant impact on spore populations. Our work shows that, using the studied system, pressurized CO₂ results in greater microbial lethality in milk above critical temperatures than below and suggests that a critical concentration threshold level of CO₂ is required for lethal effects. Our work also suggests that supercritical CO₂ processing in a continuous flow system can achieve reductions in some microbial populations equal to or better than that typically achieved during high-temperature, short-time pasteurization.