Extraction of rice brain oil using supercritical carbon dioxide and propane

Extraction of rice bran lipids was performed using supercritical carbon dioxide (SC−CO₂) and liquid propane. To provide a basis for extraction efficiency, accelerated solvent extraction with hexane was performed at 100°C and 10.34 MPa. Extraction pressure was varied for propane and SC−CO₂ extractions. Also, the role of temperature in SC−CO₂ extraction efficiency was investigated at 45,65, and 85°C. For the SC−CO₂ experiments, extraction efficiencies were proportional to pressure and inversely proportional to temperature, and the maximal yield of oil achieved using SC−CO₂ was 0.222±0.013 kg of oil extracted per kg of rice bran for conditions of 45°C and 35 MPa. The maximal yield achieved with propane was 0.224±0.016 kg of oil per kg of rice bran at 0.76 MPa and ambient temperature. The maximum extraction efficiencies of both SC−CO₂ and propane were found to be significantly different from the hexane extraction baseline yield, which was 0.261±0.005 kg oil extracted per kg of rice bran. A simulated economic analysis was performed on the possibility of using SC−CO₂ and propane extraction technologies to remove oil from rice bran generated in Mississippi. Although the economic analysis was based on the maximal extraction efficiency for each technology, neither process resulted in a positive rate of return on investment.     

Oxidative stability of sunflower oil extracted with supercritical carbon dioxide

Extraction of oilseeds with supercritical carbon dioxide (SC−CO₂) is a promising technique to obtain vegetable oils. However, instability of such oils has been associated in the past with SC−CO₂ extraction. The reasons underlying such instability were unclear. Results presented here suggest that oil instability may be related to the oxygen content of CO₂. In fact, oil stability decreases sharply when refined oil (additive-free) is re-extracted with SC−CO₂ and can be related to the oxygen content in the CO₂. Never-theless, oil stability could be improved to the level of conventionally extracted oil by adding trace amounts of ascorbic acid.     

Pilot-scale supercritical carbon dioxide extraction and fractionation of wheat germ oil

There is a need for the development of new processing techniques to facilitate vegetable oil extraction and refining while sustaining the nutritional components naturally present in edible oils and reducing the adverse impact of oil processing on the environment. In this study supercritical carbon dioxide (SC−CO₂) extraction and fractionation techniques were examined as alternative methods to obtain wheat germ oil (WGO) of high quality and purity. It was shown that the SC−CO₂ extraction technique is effective in extraction of WGO. There was no significant difference in the FA composition of SC−CO₂- and hexane-extracted WGO. Both hexane-and SC−CO₂-extracted WGO were rich in α-tocopherol. Moisture content of the SC−CO₂-extracted oil was higher than that of the hexane-extracted oil. Solvent/feed ratio had a significant effect on the SC−CO₂ extraction yields. This study demonstrated that supercritical fluid fractionation was a viable process to remove FFA efficiently from both hexane-and SC−CO₂-extracted WGO while retaining bioactive oil components in the final product.     

Oxidation,flavor, and texture of walnuts reduced in fat content by supercritical carbon dioxide

English walnuts are popular because of their good taste, high n−3 FA content, and reported hypocholesterolemic effects. However, walnuts have a high fat content (∼70% w/w) that is highly polyunsaturated, which contributes to oxidative instability. The objectives of this study were: (i) to use supercritical carbon dioxide (SC-CO₂) extraction to decrease the total fat content of walnuts, and (ii) to determine the effects of SC-CO₂ lipid extraction on the oxidative stability, flavor, and textural characteristics of the reduced-fat walnuts. The fat content of English walnut pieces was reduced by 25 and 40% with a pilot-scale SC-CO₂ extraction system. Full-fat, 25-, and 40%-reduced-fat walnuts were stored at 25 and 40°C for 8 wk. FA profiles were similar for residual oil in all treatments, and the profiles did not change with storage. PV and volatile compounds were significantly greater (P<0.05) in full-fat walnuts than in reduced-fat walnuts at both storage temperatures. A trained sensory panel judged the reduced-fat walnuts to be less astringent and to have less walnut and rancid flavors. Full-fat walnuts had greater hardness than reduced-fat walnuts by both sensory and instrumental texture profile analyses. In general, reducing the relative fat contents of walnuts by 25% improved oxidative stability and maintained a high level of consumer acceptance.     

Improved lipase-catalyzed incorporation of long-chain fatty acids into medium-chain triglycerides assisted by supercritical carbon dioxide extraction

Displacement of the equilibrium of the lipase-catalyzed interesterification between medium-chain triglyceride (MCT) and long-chain polyunsaturated fatty acid was accomplished by the removal of by-products with continuous supercritical carbon dioxide (SC−CO₂) extraction at 60°C and 100 kg/cm². The incorporation of eicosapentaenoic acid to MCT was appreciably improved by this method and was 1.3 times higher than that of the equilibrium state (47 wt%) that was obtained in a closed system. The immobilizedMucor miehei lipase was stable for more than 180 h in SC−CO₂ at 60°C and 100 kg/cm². Presented at ISF-JOCS World Congress, Tokyo, Japan, September 26–30, 1988.     

Effect of extraction methods on lipid yield and fatty acid composition of lipid classes containing γ-linolenic acid extracted from fungi

The effect of extraction procedures on the lipid yield and fatty acid composition of total lipid and main lipid structures (phospholipids, diacylglycerols, triacylglycerols, free fatty acids, and sterol esters) of fungal biomass (Mucor mucedo CCF-1384) containing γ-linolenic acid (GLA) was investigated. Seventeen extraction methods, divided into three groups, were tested: six with chloroform/methanol, five with hexane/alcohols, and six with common solvents or mixtures. The chloroform/methanol procedure (2∶1) was selected as standard, where lipid yield (TL/DCW, total lipid per dry cell weight) was 17.8%, considered to be 100% of lipids present. All chloroform/methanol extractions yielded more than 83% recorvey of lipids. Use of hexane/isopropanol solvent systems led to a maximum of 75% recovery. The best lipid yield was achieved by a two-step extraction with ethanol and hexane (120%). Extraction efficiency of the other solvent systems reached a maximum of 73%. Triacylglycerols were the main structures of lipid isolated; only methanol-extracted lipid contained 58.5% phospholipids. The fatty acid content of total recovered lipid was variable and depended on both the lipid class composition and the solvent system. GLA concentrations in total lipids isolated by hexane/alcohol procedures (7.3–10.7%) are comparable with classical chloroform/methanol systems (6.5–10.0%). The maximal GLA yield was obtained with chloroform/methanol/n-butanol/water/0.1 M ethylenediaminetetraacetic acid (EDTA) (2∶1∶1∶1∶0.1, by vol) and after two-step extraction with ethanol and hexane (14.3 and 13.7 g GLA/kg DCW, respectively). The highest GLA content was analyzed in the phospholipid fraction (16.1%) after using chloroform/methanol/n-butanol/water/0.1 M EDTA (2∶1∶1∶1∶0.1, by vol). Remarkably low concentrations of polyunsaturated fatty acids were determined in the free fatty acid fraction.     

Accelerated Solvent Extraction Improves Efficiency of Lipid Removal from Dry Pet Food While Limiting Lipid Oxidation

Accelerated solvent extraction (ASE) was evaluated for extracting lipids from baked and extruded dry pet foods to determine factors controlling extraction efficiency and effects on lipid oxidation. Hydroperoxide decomposition and new lipid oxidation were minimal at 40 °C but increased at higher extraction temperatures without increasing yields. Maximum extraction required grinding samples to 250 µm particles, presence of polar solvents [chloroform, chloroform/methanol 2:1 (v/v) mixed, hexane/methanol 2:1 (v/v)], and a minimum of 20 min total static extraction time in repeat extraction cycles. Hexane and methanol injected into extraction cells simultaneously but separately was able to nearly duplicate extractions of chloroform/methanol, providing an option for replacing toxic chlorinated hydrocarbon solvents in ASE. However, lipid oxidation was higher in hexane. Yields were quantitative in baked biscuits but lower in extruded kibbles due to more dense, complex molecular structures. ASE extraction yields of 40 min or less were comparable to manual extraction yields of 24–48 h, with lower oxidation. Overall, one or two ASE extraction cycles with static times less than 20 min appeared to provide adequate lipid yields that accurately reflect lipid composition while inducing minimal modification when lipid oxidation products are the analytical endpoint.     

Optimization of an Oil Extraction Process for Algae from the Treatment of Manure Effluent

Increasing interest in the coupling of biological wastewater treatment processes with the generation of value-added products (such as oil containing ω-3 fatty acids (FA)) has stimulated efforts in adapting extraction methods for treatment byproducts. This study’s objective was to compare a high temperature/pressure extraction method (accelerated solvent extraction) (ASE) and a manual extraction method (modified Folch extraction) with regard to their ability to extract total oil from three algae samples from the treatment of dairy manure effluent. The efficiency of total oil and FA extraction with three solvents (chloroform/methanol, isopropanol/hexane, and hexane) was also evaluated using the ASE method. Results showed that the ASE method yielded higher values for total oil content compared to the Folch method but similar values for FA content and composition after four extraction cycles with chloroform/methanol. However, the ASE method yielded much higher amounts of FA in the first cycle (85–95% of total extracted) compared to the Folch method (44–55% of total extracted in the first cycle). As expected, the extraction efficiency of the ASE method for FA was dependent on the extraction solvent. FA content values using ASE with chloroform/methanol > isopropanol/hexane > hexane. FA content values using the Folch method or ASE with chloroform/methanol were not significantly influenced by sample particle size within the size range of 0.1–1 mm.     

Optimization of cell wall disruption and lipid extraction methods by combining different solvents from wet Chlorella vulgaris

Over the past few decades, microalgae have emerged as a promising option for making lipid-based bioactive compounds. The purpose of this study was to extract lipids from Chlorella vulgaris. In this study, different cell wall disruption methods such as microwave, liquid nitrogen, ultrasound (US), and bead mill were compared. We selected and optimized two systems based on their efficacy in disrupting cell walls—US and beads mill. Based on the dry weight of C. vulgaris biomass, the maximum lipid extraction by the US was 17.1% and by bead mill was 15.2%. Following cell wall disruption of C. vulgaris, chloroform–methanol (2:1) solvent combination achieved high lipid extraction. However, the hexane–ethanol (1:1) solvent combination was chosen because of its lower toxicity. Specifically, the effect of the solvent-to-biomass ratio, the temperature, and the extraction time was investigated. The results indicated that the chloroform–methanol solvent combination yielded optimal results at 8 ml/g solvents to biomass, 45°C, and 60 min and that the hexane–ethanol combination yielded optimal results at 6 ml/g, 35°C, and 73 min, respectively. The highest amount of lipids was obtained from C. vulgaris with 87.6% moisture content. As a cell wall disruption method, the US obtained 20.4% and 16.4% with a combination of chloroform–methanol solvents and hexane–ethanol, respectively. Additionally, bead milling resulted in the highest extraction yield of 17.6% for chloroform–methanol and 13.9% for hexane–ethanol. Based on the results of cell wall disruption, the US method is the most efficient cell wall disruption method in terms of lipid extraction efficiency.     

Pressurized liquid extraction of polar and nonpolar lipids in corn and oats with hexane,methylene chloride,isopropanol, and ethanol

Samples of freshly ground corn kernels and freshly ground rolled oats were extracted via pressurized liquid extraction (accelerated solvent extraction) using four different organic solvents [hexane, methylene chloride (also known as dichloromethane), isopropanol, and ethanol] at two temperatures (40 and 100°C). Lipid yields varied from 2.9 to 5.9 wt% for ground corn and from 5.5 to 6.7 wt% for ground oats. With ground corn, more lipid was extracted as solvent polarity was increased, and for each individual solvent, more lipid was extracted at 100°C than at 40°C. With ground oats, the same temperature effects was observed, but the solvent polarity effect was more complex. For both corn and oats, methylene chloride extracted the highest levels of each of the nonpolar lipid classes. In general, for both corn and oats, icnreasing solvent polarity resulted in increasing yields of polar lipids, and for each solvent, more of each lipid class was extracted at 100°C, than at 40°C. Among the lipids in corn extracts, the phytosterols may be the most valuable, and total phytosterols ranged from about 0.6 wt% in the hot ethanol extracts to about 2.1 wt% in the hot hexane and methylene chloride extracts. Total phytosterols in all oat extracts were about 0.1 wt%. Digalactosyldiacylglycerol was the most abundant polar lipid in the oat extracts; its levels ranged from 1.6 wt% in the cold hexane extracts to 4.3 wt% in the hot ethanol extracts.     

Continuous fractionation of used frying oil by supercritical CO<Subscript>2</Subscript>

Fractionation by supercritical carbon dioxide (SC−CO₂) might be a way to purify used frying oils, since a selective separation of the oil components based on their polarity and M.W. can be attained. In this work, we studied the purification of peanut oil used for frying by SC−CO₂ continuous fractionation in a packed column. The influence of pressure (15–35 MPa) and temperature (25–55°C) on the yield and on the composition of products was determined. The composition of the top and bottom products was evaluated by using size-exclusion chromatography and other accepted chemical methods. Process conditions were selected to separate TG from degraded compounds. Experimental results indicated that the operating conditions leading to maximal TG recovery in the extract were 35 MPa, 55°C, and a solvent-to-feed ratio of 53. By operating at these conditions, it was possible to recover 97% of the TG placed on the column and about 52% by weight of the used frying oil. The composition of the purified top stream was very similar to that of fresh frying oil.     

Supercritical fluid extraction of lipids from broccoli leaves

The supercritical fluid extraction (SFE) and fractionation of lipids from broccoli leaves is presented in this work. For this purpose the effect of the different variables on the extraction was studied, obtaining the best results at 60°C, 300 bar and 3 mL/min. Two different fractions were obtained: First, the samples were extracted with pure CO₂, and afterward the residual material was extracted using CO₂ modified with 15% of methanol. The total fatty acid content of the extracts was determined by GC‐MS and compared with those results obtained by Soxhlet extraction with hexane and a chloroform/methanol (2:1) mixture. The SFE extracts presented a higher percentage of unsaturated fatty acids, especially the polyunsaturated 18:3 n ? 3. The methodology was successfully applied to the analysis of the fatty acid composition of the leaves from five different cultivars of broccoli. In all the samples the main fatty acids were α‐linolenic (18:3 n ? 3), linoleic (18:2 n ? 6), and palmitic (16:0). Among the different cultivars analyzed, Naxos variety presented the highest levels in fatty acids, while Parthenon and Viola the lowest. Practical applications: The proposed method allows the fractionation of lipids from broccoli leaves using a small volume of organic solvent and mild conditions. This is advantageous compared to conventional methods where large volumes or organic solvents are used, and the cost and time for the removal of these solvents, along with the possibility of degradation and toxicity, are the major disadvantages. The results obtained contribute to a better compositional characterization and a possible revaluation of this by‐product as a source of biologically active compounds.     

Recovery of Oil,Erucic Acid,and Phenolic Compounds from Rapeseed and Rocket Seeds

Erucic acid‐enriched oil, sought for industrial purposes, from rapeseed (agronomic plant) and rocket seeds (non‐agronomic plant) was extracted by three different processes: supercritical CO₂, mechanical expression, and hexane extraction. Oil extraction yields were determined and the extracted oils were characterized for their fatty acid and phenolic compound compositions. Higher oil yields were achieved using hexane compared to mechanical expression and supercritical CO₂ extractions. Fatty acid analysis indicated a higher content of erucic acid in rapeseed oil than in rocket oil. In addition, supercritical CO₂ extraction allowed better recovery of phenolic compounds with high antioxidant activities. The most prominent identified polyphenols were vanillin, sinapic acid, syringic acid, and apigenin.     

Characterization of oil including astaxanthin extracted from krill (Euphausia superba) using supercritical carbon dioxide and organic solvent as comparative method

Krill oil including astaxanthin was extracted using supercritical CO₂ and hexane. The effects of different parameters such as pressure (15 to 25MPa), temperature (35 to 45 °C), and extraction time, were investigated. The flow rate of CO₂ (22 gmin⁻¹) was constant for the entire extraction period of 2.5 h. The maximum oil yield was found at higher extraction temperature and pressure. The oil obtained by SC-CO₂ extraction contained a high percentage of polyunsaturated fatty acids, especially EPA and DHA. The acidity and peroxide value of krill oil obtained by SC-CO₂ extraction were lower than that of the oil obtained by hexane. The SC-CO₂ extracted oil showed more stability than the oil obtained by hexane extraction. The amount of astaxanthin in krill oil was determined by HPLC and compared at different extraction conditions. The maximum yield of astaxanthin was found in krill oil extracted at 25 MPa and 45 °C.     

Determination of aflatoxin M1 in raw milk: A modified Jacobson,Harmeyer and Wiseman method

A modification of the method of Jacobson, Harmeyer and Wiseman for the determination of aflatoxin M₁ in raw milk is made, eliminating the column clean-up which gives clean extracts, and good recoveries comparable to the parent procedure. Recoveries within the limits of visual comparison are obtained from spiked raw milk samples containing 0.3 ppb, and clean-up is sufficient to quantitize levels of 0.2 ppb in naturally contaminated raw milk. Deproteinized milk (80% methanol extracts) is adjusted to a 50% methanol concentration with 4% sodium chloride solution and lipids removed by extraction with hexane. Aflatoxin M₁ is extracted from the 50% methanol and sodium chloride phase with chloroform. The chloroform extract containing aflatoxin M₁ is then washed with 4% sodium chloride solution dried over anhydrous sodium sulfate and evaporated on a steam bath under nitrogen. The dry residue is then dissolved in chloroform and spotted on silica gel thin layer plate and developed according to the procedure of Stubblefield, Shotwell and Shannon.     

Comparison of supercritical CO2 and hexane extraction of lipids from sorghum distillers grains

Total yields and compositions of sorghum dried distillers grains with solubles (DDGS) lipids obtained by supercritical CO₂ (SC‐CO₂) extraction were compared with those obtained by recirculated solvent extraction (RSE) with hexane. The total yield of lipids obtained by SC‐CO₂ extraction at 27.5 MPa and 70 °C was 150 g lipids/kg DDGS, while the yield obtained by RSE with hexane at 69 °C was only 85 g lipids/kg DDGS. The contents of four high‐value compounds, i.e., policosanols, phytosterols, free fatty acids (FFA) and tocols, in the lipids obtained by SC‐CO₂ extraction were 31.2, 15.6, 155.3 and 0.50 mg/g at 27.5 MPa and 70 °C, compared to 26.6, 9.6, 57.3 and 0.03 mg/g for RSE with hexane at 69 °C. The profiles of phytosterols and FFA in the sorghum DDGS lipids were relatively independent of the extraction methods and operating conditions.     

Influence of operation variables on quality parameters of olive husk oil extracted with CO<Subscript>2</Subscript>: Three-step sequential extraction

Supercritical CO₂ extraction is a viable alternative process for the extraction of high-quality oil from olive husk (also known as olive pomace), a residue obtained in the production of olive oil. We analyzed the effect of pressure (100–300 bar), temperature (40–60°C), solvent flow (1–1.5 L/min), and particle size (0.30–0.55 mm) on four important quality parameters of the oil extracted with CO₂: tocopherol concentration, extinction coefficients at 232 and 270 nm, and saponification value. Response surface methodology was used to obtain mathematical expressions related to the operating variables and parameters studied. Results from these experiments were also used to design a three-step sequential CO₂ extraction procedure to obtain a higher-quality extract. The optimal operational sequence consisted of a first extraction step at 75 bar for 1 h using 1% (vol/vol) ethanol modifier, followed by a second extraction stage at 350 bar for 2.5 h without ethanol and a third step, also at 350 bar, for 2.5 h but using ethanol. These extraction conditions obtained an intermediate fraction of oil with 64% yield and all normal parameters according to European Commission food legislation. This fraction is suitable without any further refining. On the contrary, the oils obtained by hexane extraction and by conventional supercritical CO₂ extraction at optimal conditions are suitable for human consumption after further refining. This last finding may result in improved economics of the sequential CO₂ extraction process compared to the conventional extraction method with hexane.     

Improved Methods for the Fatty Acid Analysis of Blood Lipid Classes

Two improved methods have been developed for preparation of fatty acid methyl esters (FAME) from major O-ester lipid classes in blood, i.e., cholesterol ester, triacylglycerol, and glycerophospholipids. The methods involve simple operations, and use neither harmful solvents such as chloroform or benzene nor highly reactive volatile reagents such as acetyl chloride. The FAME synthesis reaction proceeds under mild temperature conditions. The methods include (1) extraction of lipids from 0.2 ml of blood with 0.2 ml of tert-butyl methyl ether and 0.1 ml of methanol, (2) separation of the total lipids into lipid classes using a solid-phase extraction column or thin-layer chromatography, and (3) methanolysis of each lipid class at room temperature or at 45 °C. In all the operations, solvent concentration is performed only once prior to gas–liquid chromatography (GC). No noticeable differences in composition determined by GC have been found between FAME prepared by the present methods and those prepared by a conventional method involving lipid extraction with chloroform/methanol. The mild reaction and simplified procedures of the present methods enabled safe and reproducible analysis of the fatty acid compositions of the major ester-lipid classes in blood.     

Use of liquid carbon dioxide to remove hexane from soybean oil

Liquid carbon dioxide (L-CO₂) was investigated as a means to separate hexane from the mixture of soybean oil (SBO) and hexane resulting from the hexane extraction of soybeans. Using a fractionation tower, 5 vol of CO₂ (i.e., 100, 200, 300, 500, and 1000 L expanded gas) were passed through 50 mL of two concentrations of n-hexane (i.e., 10 and 25% w/w) in SBO. After passing through the hexane/SBO mixture, the expanded CO₂ was passed through a chilled collection flask to capture extracted hexane and SBO. The raffinate SBO was removed from the column and analyzed for residual hexane using International Organization for Standardization Method 9832:2002. Residual hexane decreased as the amount of L-CO₂ used increased and was less than 20 ppm after 200 L of CO₂. The amount of SBO extracted increased with the volume of CO₂ used. Significantly more SBO and hexane were collected from the 25% sample than the 10% sample. During the extraction of the mixture, the CO₂ selectively carried over TG with lower M.W. This research demonstrates the ability to use L-CO₂ to remove haxane from mixtures of hexane and SBO at both low pressures and temperatures.     

Diferuloylputrescine and p-coumaroyl-feruloylputrescine, abundant polyamine conjugates in lipid extracts of maize kernels

Extraction of corn bran or corn fiber with polar solvents such as methylene chloride, ethanol or chloroform/methanol yielded common lipids and two unknown high-performance liquid chromatography (HPLC) peaks, each with an ultraviolet absorbance maximum at 320 nm. HPLC-mass spectrometry revealed that the unknowns were diferuloylputrescine (DFP) and p-coumaroyl-feruloylputrescine (CFP). When compared to extracts of corn fiber (a pericarp-enriched fraction from the wet milling of corn), comparable extracts of corn bran (a pericarp- enriched fraction from the dry milling of corn) yielded three- to eightfold higher levels of DFP and CFP. Extraction of corn bran or fiber with an accelerated solvent extractor revealed that elevated temperatures greatly enhanced the extraction of DFP and CFP by methylene chloride and ethanol. “Corn bran oil,” prepared by extraction of corn bran with hot methylene chloride, contained 14 wt% DFP and 3 wt% CFP. However, when hexane was used as a solvent, accelerated solvent extraction of the corn bran or fiber did not extract any DFP or CFP. Extraction of wheat bran or psyllium hulls with hot methylene chloride did not yield any detectable DFP or CFP. Because it has been suggested that polyamine conjugates such as DFP and CFP may function as natural pesticides, a rapid method was developed to purify them so that their biological activity could be evaluated.