Supercritical carbon dioxide extraction ofDimorphotheca pluvialis oil seeds

The possibility of extraction ofDimorphotheca oil with supercritical carbon dioxide is demonstrated in this article. Before extraction, the seeds have to be pretreated to improve extraction yield. Experiments showed that the best pretreatment procedure forDimorphotheca was heating the seeds under reduced pressure to 100°C for 60 min, followed by flaking or milling. To give an impression about the efficiency of the supercritical extraction, a mathematical model has been developed to estimate the overall mass transfer coefficient (A _p K). Also, an empirical relation betweenA _p K and the interstitial velocity has been found. The physical properties of the supercriticalDimorphotheca oil are in good agreement with those of conventionally extracted oil, except for a lower phospholipid content. It is expected that further refining of supercriticalDimorphotheca oil will be marginal.     

Deacidification of black cumin seed oil by selective supercritical carbon dioxide extraction

The deacidification of high-acidity oils from Black cumin seeds (Nigella sativa) was investigated with supercritical carbon dioxide at two temperatures (40 and 60°C), pressures (15 and 20 MPa) and polarities (pure CO₂ and CO₂/10% MeOH). For pure CO₂ at a relatively low pressure (15 MPa) and relatively high temperature (60°C), the deacidification of a highacidity (37.7 wt% free fatty acid) oil to a low-acidity (7.8 wt% free fatty acid) oil was achieved. The free fatty acids were quantitatively (90 wt%) extracted from the oil and left the majority (77 wt%) of the valuable neutral oils in the seed to be recovered at a later stage by using a higher extraction pressure. By reducing the extraction temperature to 40°C, increasing the extraction pressure to 20 MPa, or increasing the polarity of the supercritical fluid via the addition of a methanol modifier, the selectivity of the extraction was significantly reduced; the amount of neutral oil that co-extracted with the free fatty acids was increased from 23 to 94 wt%.     

Properties and processing of corn oils obtained by extraction with supercritical carbon dioxide

Crude oils were extracted from wet- and dry-milled corn germs with supercritical carbon dioxide (SC-CO₂) at 50–90 C and 8,000–12,000 psi and were characterized for color, free fatty acids, phosphorus, refining loss, unsaponifiable matter, tocopherol and iron content. They were compared with commercial products. Extraction of wetmilled germ with SC-CO₂ has some advantages over the conventional prepress solvent method commonly used in the industry. For example, SC-CO₂ extraction of wet-milled germ at 50 C and 8,000 psi yields crude oil with a lower refining loss and a lighter color. After laboratory processing, a light-colored, bland salad oil is obtained. Crude, refined, bleached and deodorized oils from SC-CO₂-extracted dry-milled germ appear equivalent to those obtained by expeller pressing. Presented in part at AOCS meeting, Toronto, Ontario, Canada, May 1982.     

Bioactive Components of Commercial and Supercritical Carbon Dioxide Processed Wheat Germ Oil

Wheat germ oil (WGO) is a specialty product with a very high nutritional value. The chemical composition of both commercial and pilot scale supercritical carbon dioxide (SC-CO₂) processed WGO was examined. This study showed that methods used for oil extraction and refining did not have a significant effect on the fatty acid composition of the oil. SC-CO₂ extracted oil had a higher tocopherol content than that of commercially hexane extracted oil. The phospholipid content of the SC-CO₂ extracted oil was very low indicating that the SC-CO₂ extraction method could eliminate the degumming step from edible oil refining processes. Although the conventional chemical oil refining technique reduced the tocopherol content of the WGO, it was possible to concentrate tocopherols in WGO by using physical refining methods such as molecular distillation. Published with approval of the Director, Oklahoma Agricultural Experiment Station.     

Quality of residual oil from palm-pressed mesocarp fiber (Elaeis guineensis) using supercritical CO2 with and without ethanol

The qualities of oils extracted from fresh and dried palm-pressed mesocarp fiber were evaluated. The means of extraction included conventional solvent extraction and supercritical carbon dioxide (SC-CO₂) extraction with and without addition of ethanol. Extraction efficiency using pure SC-CO₂ and the effect of moisture content on efficiency were studied. Minor components, such as vitamin F, carotenoids, squalene and phytosterols, obtained by different methods were compared. The quality of oil recovered from fresh palm-pressed fiber is generally better than that of oil recovered from dried fiber. The SC-CO₂ extraction rate was lower for fresh fiber than for dried fiber. The incorporation of ethanol with SC-CO₂ resulted in oil with higher oxidative stability than did SC-CO₂ alone. Concentrations of minor components and the acylglycerol compositions of the oils extracted from both types of fibers were similar.     

Refining normal and genetically enhanced soybean oils obtained by various extraction methods

Four different extraction methods, extrusion-expelling, conventional flaking-solvent extraction, expander-solvent extraction, and screw pressing, were used to separate oil and meal of a commodity soybean. The quality and refining characteristics of oils obtained by these methods were evaluated, and the effects of extraction method on oil quality were determined. The screw-pressed oil was more oxidized and hydrolyzed than the oils from the other extraction methods. The extruded-expelled oil had oxidative status similar to the solvent-extracted oils, although it contained the lowest amount of tocopherols. Five genetically enhanced soybeans were also processed by extrusion-expelling and solvent extraction methods, and differences in refining of these oils were examined. Overall, extruded-expelled oils were significantly different from the solvent-extracted oils in that they contained less tocopherols and were more oxidized than the solvent-extracted oils during refining. The differences between oils from the two extraction methods were magnified owing to the inclusion in the experiment of oils with modified compositions. The more unsaturated oils underwent significantly more oxidative degradation during refining than did the more saturated ones.     

葡萄籽油的提取方法及精炼工艺研究进展

葡萄酒生产过程中的下脚料,经过清洗、烘干等处理,分离出葡萄籽.所得葡萄籽通过压榨法、溶剂提取法或超临界流体萃取法得到葡萄籽毛油,所得毛油经脱胶、脱酸、水洗干燥、脱色、脱臭、特色过滤等精炼工艺最后得到精制成品油.本文对葡萄籽油的提取方法及精炼工艺研究进展进行了综述.     

Extraction of lipids from Yarrowia Lipolytica

BACKGROUND: Microorganisms have often been considered for the production of oils and fats as an alternative to agricultural and animal resources. Extraction experiments were performed using a strain of the yeast Yarrowia lipolytica (Y. lipolytica), a high‐lipid‐content yeast. Three different methods were tested: Soxhlet extraction, accelerated solvent extraction (ASE) and supercritical carbon dioxide (SCCO₂) extraction using ethanol as a co‐solvent. Also, high pressure solubility measurements in the systems ‘CO₂ + yeast oil’ and ‘CO₂ + ethanol + yeast oil’ were carried out. RESULTS: The solubility experiments determined that, at the conditions of the supercritical extractor (40 °C and 20 MPa), a maximum concentration of 10 mg of yeast oil per g of solvent can be expected in pure CO₂. 10% w/w of ethanol in the solvent mixture increased this value to almost 15 mg of yeast oil per g of solvent. Different pretreatments were necessary to obtain satisfactory yields in the extraction experiments. The Soxhlet and the ASE method were not able to complete the lipid extraction. The ‘SCCO₂ + ethanol’ extraction curves revealed the influence of the different pretreatments on the extraction mechanism. CONCLUSION: Evaluating the effectiveness of a given pretreatment, ASE reduced the amount of material and solvent used compared with Soxhlet. In all three cases, the best total extraction performance was obtained for the ethanol‐macerated yeast (EtM). Addition of ethanol to the solvent mixture enhanced the oil solubility. Oil can be extracted from Y. lipolytica in two different steps: a non‐selective ethanol extraction followed by TAG‐selective SCCO₂ purification. © 2012 Society of Chemical Industry     

Purification of Waste Cooking Oils via Supercritical Carbon Dioxide Extraction

Purification of waste cooking oils (palm oil and soybean oil) using supercritical carbon dioxide (scCO₂) extraction has been investigated. The purified oils were characterized by their acid value, conjugated diene value, total polar compound measurements, and high-performance size exclusion chromatography. Using optimal extractions conditions of 353.15 K, 20 MPa, and CO₂ flow rate of 40 g/min, 80% of the oil was recovered and the purified oil compositions and properties were very close to those of the fresh oils. At higher pressures or lower temperatures, the separation efficiency of the scCO₂ extraction was significantly reduced.     

Liquefied gases and supercritical fluids in oilseed extraction

Soybean oil and numerous other vegetable oils can be extracted from crushed seeds by means of liquefied gases or supercritical fluids. The oils are recovered by lowering the pressure or increasing the temperature, or both. Supercritical carbon dioxide is ideally suited for the food industry as it is nontoxic and nonflammable. Moreover, it can be removed easily from the oil as well as the meal. The oils extracted with supercritical carbon dioxide contain much lower proportions of phospholipids than those obtained by conventional processing with hexane. The addition of acetone or another carrier or entrainer aids in the fractional extraction of lipids differing in polarity. The range of applicability of liquefied gases and supercritical fluids in the extraction and fractionation of lipids should be explored further to develop industrial processes using these solvents.     

Tunisian Pistacia atlantica Desf. Extraction Process: Impact on Chemical and Nutritional Characteristics

Plant materials have been used in different fields such as therapeutics, cosmetics, and energy for ages. Several studies have investigated seeds, whether common or not, in order to ensure a better valuation of natural resources. Among these, Pistacia atlantica Desf. has been the subject of several works on its characterization and valorization. Among the current trends in sustainable development and environmental protection, valorizing natural wild plants via green chemistry has become prevalent. One of these plants, Pistacia atlantica Desf., is a tree that grows in arid and semi-arid areas, notably in Tunisia, and produces seeds rich in oil. In this study extracting the oil from its seeds is tried by three methods (supercritical carbon dioxide (CO₂), pressure, and hexane), and the efficiency of these extraction processes is compared in order to obtain the best yield and maximize its valorization in a variety of industrial fields. The obtained oil is found to be rich in polyunsaturated fatty acids, namely linoleic and oleic acids, with a similar acidic composition among all extraction methods. The tocopherol composition of the oil is determined using high performance liquid chromatography. The total polyphenol content is determined using the Folin-Ciocalteu colorimetric analysis method. The results show that the seed oil of Pistacia atlantica Desf. extracted by supercritical CO₂ gives the highest extraction yield (25%) and the lowest acidity and peroxide values with a high degree of oxidation at 232 and 270 nm. This method also gives the highest content of alpha, gamma, and delta tocopherol as well as total phenolic content compared to the other extraction methods. The composition of chlorophylls and carotenes in the seed oil of Pistacia atlantica Desf. is determined. Besides, the analysis of the sterol composition reveals that β-sitosterol is still prevailing. Among all the tested extracts, the supercritical CO₂ extract demonstrates the best antioxidant performance against the tested radicals. The oil extracted by supercritical carbon dioxide (CO₂) is of a higher quality compared to that extracted by pressure and by hexane. Practical applications : The Pistacia atlantica Desf. oil exhibits interesting physicochemical and biological characteristics. The type of extraction affects the quality of the major and minor components in the seeds. However, the supercritical CO₂ method produces a better oil quality with the presence of antioxidants such as tocopherols and polyphenols. In fact, it is found that the oil extracted by the three methods has an important sterolic profile with the predominance of β-sitosterol. According to the classification of vegetable oils, unsaturated fatty acids of atlas pistachio oil can be categorized as oleo linoleic oil, which enhances its nutritional value. Having these characteristics, the use of this oil can be considered in agrifood products.     

Effect of rosehip extraction process on oil and defatted meal physicochemical properties

The physicochemical properties of oil from Rosa affinis rubiginosa seeds were analyzed after extraction by (i) organic solvent, (ii) cold pressing, and (iii) cold pressing assisted by enzymatic pretreatment using a mixture of the Novo-Nordisk A/S products Cellubrix (cellulase and hemicellulase activities) and Olivex (pectinase, cellulase, and hemicellulase activities). There were no significant differences in oil quality parameters, such as iodine value, refractive index, saponification value, unsaponifiable matter, and FA profile, when applying any of the three extraction processes. Although significant variations were observed in FFA content (acid value) and PV of the oil obtained by both of the cold-pressing oil extraction processes, these results were lower than the maximum value established from the Codex Alimentarius Commission. All-trans-retinoic acid content improved by 700% in rosehip oil obtained through cold pressing, with and without enzymatic pretreatment, in comparison with organic solvent extraction. This result is quite important for cosmetic oil because all-trans-retinoic acid is the main bioactive component responsible for the regenerative properties of this oil.     

Quality differences between pre‐pressed and solvent extracted rapeseed oil

Most seed oils are obtained by pre‐pressing the crushed seeds followed by solvent extraction of oil from the press cake. The prepressed oil will contain no solvent residues, and is moreover expected to contain more nutritionally valuable compounds, which can in turn enhance the oxidative stability of the oil. However, reports on differences between extracted and pressed oils are scarce. Therefore, in this study, for a case study on rapeseed oil, the composition and quality were systematically compared between pre‐pressed and solvent extracted oil. In the extracted oil, solvent residues and a clear sensory difference were detected, which disappeared almost completely during refining. The crude oils had a high content in free fatty acids and in primary and secondary oxidation products, which were higher in the extracted than in the pressed oil. However, surprisingly, also the content of minor compounds was slightly higher in the extracted oil than in the pressed oil. This can be explained by a selective extraction of those compounds into the solvent. During refining, a difference between pressed and extracted oils still existed but was less pronounced. The slight difference in antioxidants content might explain the higher oxidative stability of extracted over pressed oils. Practical applications : Traditionally, high yields of vegetable oils are obtained by pre‐pressing the seeds, followed by solvent extraction of the residual oil from the press cake. The solvent extraction leads to higher oil yields, but is expected to affect the composition and quality of the oil, and has moreover negative environmental impacts. In this study, the solvent extracted oil contained slightly higher levels of tocopherols and phytosterols, and had slightly higher oxidative stability, which are desirable quality aspects. In contrast, the solvent extracted oil contained also higher levels of undesirable phospholipids, as well as solvent residues, which were, however, removed during degumming and deodorization, respectively. These results suggest that the final quality of refined pre‐pressed and solvent extracted oils is comparable from nutritional and safety point of view. A choice for pressing instead of solvent extraction will, therefore, rather be driven by sustainability concerns than by nutritional aspects.     

Extraction of essential oil from geranium (Pelargonium graveolens) with supercritical carbon dioxide

This study investigated the supercritical fluid extraction (SFE) of geranium essential oil from geranium (Pelargonium graveolens) using supercritical carbon dioxide solvent. The extraction yield was measured as a function of pressure, temperature and carbon dioxide flow rate. At low pressure (10 MPa) and high temperature (343 K), waxes were co‐extracted with the essential oil, resulting in artificially elevated essential oil extraction yields as no method was available with the SFE apparatus used to separate co‐extracted waxes and oil. At high pressure (30 MPa) and low temperature (313 K), the amount of wax co‐extracted decreased. Under these ‘optimum’ conditions, the extraction yield increased with decrease in flow rate giving a maximum extraction yield of 2.53%. All samples were analyzed by gas chromatography–mass spectrometry and the effect of pressure and extraction time on oil composition was studied. The percentage compositions of terpene hydrocarbons, terpenols, geraniol and geranyl esters were significantly affected by pressure and extraction time. The oil samples obtained by SFE were also compared with commercially obtained steam distilled samples. All major components of the commercially obtained oils were present in the SFE‐obtained oils; however, the percentage composition of the major components differed greatly between steam distilled and SFE oils. Copyright © 2005 Society of Chemical Industry     

Quantitative extraction of pecan oil from small samples with supercritical carbon dioxide

A procedure to determine total oil content of pecan was developed for samples weighing 500 and 10 mg by supercritical fluid extraction (SFE) with carbon dioxide as the extraction solvent, and chilled hexane as the trapping solvent. Fatty acid methyl esters (FAMEs) were prepared from the total lipid fraction by using either an aliquot (500 mg starting weight) or the entire extract (10 mg starting weight). Total oil content obtained for either sample size with SFE was similar to that obtained with an organic solvent extraction technique. The fatty acid composition for the total lipid fraction of oils extracted with SFE was the same as for oils extracted with organic solvents, and oil composition did not change during SFE. Both oil yield and fatty acid composition were similar to those reported previously for pecan. Samples could be extracted and placed into FAME-derivatizing reagents in one day, and fatty acid composition of the total lipid fraction could be determined by gas-liquid chromatography the next day. The procedure, as demonstrated for pecan, should be suitable for other oilseeds, especially those containing low amounts of water.     

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.     

Hybrid <Emphasis Type="Italic">Hibiscus</Emphasis> seed oil compositions

The seeds of cultivated Hibiscus spp. were extracted with supercritical carbon dioxide, and the resulting extracts were analyzed to identify the major TG components as the corresponding FAME. The seed oils were composed predominantly of oleic and linoleic FA (69.6–83.4%) with lesser amounts of palmitic acid (14.8–27.0%). Minor amounts of C14, C18, and C20 saturated FA were also detected. The oil content of the seeds was determined to be between 11.8 and 22.1 wt% for hybrid varieties and between 8.9 and 29.5 wt% for the native species from which the hybrid varieties were developed. The protein content of the defatted seed meal averaged 20% for the hybrid varieties. The composition of the extracted hibiscus seed oils suggests potential edible applications.     

Total fatty acid analysis of vegetable oil soapstocks by supercritical fluid extraction/reaction

Soapstock from vegetable oil refining operations is a value-added by-product that finds further industrial use based on its fatty acid content. Since the fatty acid content of soapstock can vary according to its vegetable oil source or method of refining, determination of its total fatty acid (TFA) by an accurate analytical method is of key importance to purchasers of this refinery by-product. Traditionally, the TFA content of soapstock has been determined by the AOCS Official Method G3-53 based on a gravimetric assay. Unfortunately, this gravimetric-based assay requires considerable time and incorporates a considerable quantity of organic solvent per assay. In this study, the authors have applied supercritical fluid extraction (SFE) with an enzymatic-based reaction (SFR), in the presence of supercritical carbon dioxide (SC-CO₂), to determine the TFA content of soapstocks. The SFE/SFR sequence was conducted using two commercially available extractors using an in situ supported lipase in the extraction cell to form fatty acid methyl esters (FAME). Gas chromatographic (GC) determination of the individual FAME, followed by quantitation based on the calculated sum of all the fatty acids from the GC analysis, allowed a precise determination to be made of the soapstock’s TFA content. The TFA contents of three different soapstocks determined by this method were slightly higher than the values derived from Official Method G3-53. The reported method takes less than one-half of the time of Official Method G3-53 and reduces organic solvent use from 575 mL to under 2 mL of solvent by using SC-CO₂.     

The processing of new oilseed crops—An economic evaluation

The economics of pilot- to large-scale processing of the new oilssed cropsCrambe abyssinica, Euphorbia lagascae, andDimorphotheca pluvialis into oil, fatty acids, or esters were estimated. It was found that the processing costs forCrambe seed to oil is in the same range as that for rapeseed (≈0.5 U.S. $/kg). Production of fatty acid esters from vernolic and dimorphecolic acids requires some special downstream processing operations that result in processing costs of about 1 U.S. $/kg ester. Good-qualityDimorphotheca oil is much more difficult to obtain and requires supercritical carbon dioxide extraction. Processing costs can be as high as 4 U.S. $/kg oil.     

Gurum Seeds: A Potential Source of Edible Oil

Cucurbitaceae family seeds are mostly discarded as agro-industrial wastes. Gurum (Citrullus lanatus var. colocynthoide) is an underutilized wild cucurbit plant, closely related to desert watermelon, which is grown abundantly in some African countries. Gurum seeds can play a significant role in health and nutrition due to their high oil content. This review describes the nutritional composition of gurum seeds and their oil profile. Gurum seeds are a good source of oil (27–35.5%), fiber (26–31%), crude protein (15–18%), and carbohydrates (14–17%). Gurum seeds oil is extracted by supercritical CO₂ (SFE), screw press, and solvent extraction techniques. The gurum seeds oil is composed of unsaturated fatty acids with a high proportion of linoleic acid (C18:2) and oleic acid (C18:1). Gurum seeds oil contains various bioactive compounds, such as tocopherols, phytosterols, and polyphenols. It is reported that solvent extraction gives a higher yield than the screw press and SFE, but the SFE is preferred due to safety issues. More studies are required for producing better quality gurum seeds oil by using novel extraction techniques that can increase oil yield.