Extraction and characterization ofDimorphotheca pluvialis seed oil

Dimorphotheca pluvialis is increasingly recognized as an interesting industrial new oilseed crop because it contains up to 60% of the unusual fatty acid dimorphecolic acid (9-hydroxy,10t,12t-18∶2) (DA) for which new applications are being developed. In this paper, the yield, composition and quality are evaluated for dimorphotheca oils (DMO) which were recovered by pressing, conventional solvent extraction and supercritical carbon dioxide extraction (SCE). Mechanical pressing of the seeds required high temperatures and resulted in an oil recovery of only 40%, whereas the extraction protocols yielded more than 95%. Oil recovery by pressing of winged seed was even more difficult than that of unwinged seeds; hence, solvent extraction of winged seeds was preferred. The dark-colored DMO, recovered by expelling or by extraction with organic solvents, needed further refining to remove pigments and gums, whereas the light yellow-colored SCE DMO did not require further refining. SCE oil had a low phospholipid content (11 mg P/kg). Pressed oil (95 mg P/kg) and hexaneor pentane-extracted DMO (200 mgP/kg) had much higher phospholipid contents. Peroxide andp-anisidine values were low for freshly recovered oils, but increased after storage, especially in the SCE oil, due to the low concentration of natural antioxidants in SCE DMO, such as tocopherols. The DA content of the oils recovered by the various techniques showed only minor differences, except that supercritical carbon dioxide had slightly decreased solubilizing power for tri- and di-dimorphecolin as compared to hexane and pentane.     

Determination of vernolic acid content in the oil ofEuphorbia lagascae by gas and supercritical fluid chromatography

Determination of the content of vernolic acid (12,13-epoxy-9c-octadecenoic) in the oil ofEuphorbia lagascae has been performed by gas chromatography of the fatty acid methyl ester derivatives of the triacylglycerols in the oil and by supercritical fluid chromatography (SFC) of the raw oil and the fatty acid derivatives of the oil. The content of vernolic acid was found to be 55 wt%. The three methods were compared, and SFC analysis of the fatty acid derivatives was found to be the most accurate method.     

Purification of polyunsaturated fatty acid esters from tuna oil with supercritical fluid chromatography

The technical and economic feasibility of producing docosahexaenoic acid (DHA)- and eicosapentaenoic acid (EPA)-ethyl ester concentrates from transesterified tuna oil using supercritical fluid chromatography (SFC) was studied. A systematic experimental procedure was used to find the optimal values for process parameters and the maximal production rate. DHA ester concentrates up to 95 wt% purity were obtained in one chromatographic step with SFC, using CO₂ as the mobile phase at 65°C and 145 bar and octadecyl silane-type reversed-phase silica as the stationary phase. DHA ester, 0.85 g/(kg stationary phase · h) and 0.23 g EPA ester/(kg stationary phase · h) can be simutaneously produced at the respective purities of 90 and 50 wt%. The process for producing 1,000 kg DHA concentrate and 410 kg EPA concentrate per year requires 160 kg stationary phase and 2.6 tons/h carbon dioxide eluant recycle. The SFC operating cost is U.S. $550/kg DHA and EPA ethyl ester concentrate.     

Analysis of tocopherols by capillary supercritical fluid chromatography and mass spectrometry

Tocopherol-containing mixtures were analyzed by gas chromatography (GC) and capillary supercritical fluid chromatography (SFC). GC analysis of tocopherols required the formation of the silyl derivatives, while SFC analysis of the tocopherol-containing mixtures was accomplished on neat samples. SFC analysis conditions were optimized with respect to column type and density/pressure programming. Enhanced resolution of many components was achieved by using inverse temperature programming during the SFC analyses. Both SFC and GC analyses permitted the separation and quantitation of alpha-, beta-, gamma- and delta-tocopherols. In addition, SFC proved particularly applicable for characterizing the composition of a deodorizer distillate and commercial antioxidant formulation. Coupling of a quadrapole mass spectrometer with a supercritical fluid chromatograph was also achieved; the mass spectrometer provided electron impact mass spectra on the underivatized tocopherol and sterol moieties. Both SFC and SFC/mass spectrometry proved effective for the analysis of complex lipid-containing mixtures, requiring minimal sample preparation prior to analysis. Presented at the 82nd Annual Meeting of the American Oil Chemists’ Society, Chicago, IL, May 12–15, 1991.     

Separation of crude palm oil components by semipreparative supercritical fluid chromatography

Successful separation of triglycerides, diglycerides, free fatty acids, carotenes, tocopherol, and tocotrienols from crude palm oil has been achieved by supercritical fluid chromatography (SFC) with a combination of a C18 and a silica gel column. The separation was carried out by the programmed extraction elution method. Free fatty acids were separated into five components by gas-liquid chromatography; tocopherol and tocotrienols were also separated into four components by SFC analysis, and the pure fractionated carotenes were obtained by preparative SFC. Thus, by using supercritical fluid chromatography, crude palm oil components can be separated and fractionated, based on differences in their functional groups.     

Quantitative determination of triacylglycerol profile of structured lipid by capillary supercritical fluid chromatography and high-temperature gas chromatography

Two analytical methods have been developed for the qualitative and quantitative analyses of triacylglycerol profile of structured lipid (SL)-containing medium-chain and long-chain fatty acids. Supercritical fluid chromatography (SFC) was used in the first method. The SL was dissolved in chloroform/methanol, 95:5 (vol/vol), and analyzed directly using a super-critical fluid chromatograph equipped with temperature and density programming capabilities. No derivatization was required for sample preparation. An SB-methyl-100 capillary column (10 m, 100 μ i.d., 0.25 μ film thickness) was used for the separation of the triacylglycerol species and a flame-ionization detector (FID) was used for the detection. Supercritical fluid carbon dioxide was used as the mobile phase. In the second method, the SL was hydrogenated to complete saturation prior to analysis using gas chromatography at high temperatures of up to 375°C. A DB-5HT capillary column (30 m × 0.32 mm i.d., 0.1 μ film thickness) was used for the separation. FID was used for the detection and helium gas was used as mobile phase. The triacylglycerol species were separated and identified based on their equivalent carbon number (ECN), the total carbon number of the acyl side chains. A calibration curve was constructed using a triacylglycerol mixture containing known amounts of monoacyltriacylglycerol standard materials ranging from ECN 18 (trihexanoin) to ECN 66 (tridocosanoin). The novel triacylglycerol species, ECN 32–43, created by the interesterification of medium-chain triacylglycerol (MCT) and long-chain triacylglycerol (LCT) were separated and identified based on their retention times. These triacylglycerols, ECN 32–43, were absent in the physical mixture of MCT and LCT. The unique triacylglycerol specieis, ECN 32-43, were therefore selected as the fingerprinting region for the qualitative identification of the SL. Quantitation of the novel triacylglycerol species in the SL was achieved by using the integrated peak area of the new species. Both methods were employed successfully to distinguish the physical mixture from the corresponding interesterified SL. Results generated by the two methods were compared and found to be in good agreement.     

Comparison of high-temperature gas chromatography and CO2 supercritical fluid chromatography for the analysis of alcohol ethoxylates

This work compares capillary supercritical fluid chromatography (SFC) and capillary high-temperature gas chromatography (HTGC) for the quantitative characterization of nonionic alcohol ethoxylate surfactants. Supercritical fluid chromatographic separations of the alcohol ethoxylates were obtained with a density-programmed carbon dioxide mobile phase and a fused silica capillary column. High-temperature gas chromatographic separations were obtained with a high-temperature polyimide-coated fused silica capillary column. In addition, a procedure was developed for the quantitation of the capillary chromatographic data using flame ionization molar response factors based on the effective carbon theory. The alcohol and ethoxylate distributions, mean molecular weights and average moles of the ethylene oxide are rapidly calculated from the chromatographic data. Advantages and limitations of SFC and HTGC procedures are illustrated and discussed. Based on this work, the following conclusions can be drawn: i) For routine quality control analyses of known alcohol ethoxylates, SFC and HTGC appear to be equally applicable. ii) SFC has the advantage of time because derivatization is not required, although derivatization does improve resolution. iii) HTGC has the advantage of resolving C₁₂ through C₁₈ alcohol ethoxylate oligomers, avoiding ambiguous identification of components. iv)SFC and HTGC both have disadvantages. SFC has a resolution limitation and HTGC discriminates against high molecular-weight components. Presented in part at the 83rd Annual Meeting in Chicago, IL, May 1991.     

Identification of nine acetylenic fatty acids, 9-hydroxystearic acid and 9,10-epoxystearic acid in the seed oil ofJodina rhombifolia hook et arn. (Santalaceae)

In addition to some usual fatty acids, the seed oil ofJodina rhombifolia (Santalaceae) contains nine acetylenic fatty acids [9-octadecynoic acid (stearolic acid) (1.1%),trans-10-heptadecen-8-ynoic acid (pyrulic acid) (20.1%), 7-hydroxy-trans-10-heptadecen-8-ynoic acid (2.3%),trans-10,16-heptadecadien-8-ynoic acid (0.7%), 7-hydroxy-trans-10,16-heptadecadien-8-ynoic acid (0.1%),trans-11-octadecen-9-ynoic acid (ximenynic acid) (20.3%), 8-hydroxy-trans-11-octadecen-9-ynoic acid (12.2%),trans-11,17-octadecadien-9-ynoic acid (1.5%), 8-hydroxy-trans-11,17-octadecadien-9-ynoic acid (1.3%), 9-hydroxystearic acid (<0.1%) and 9,10-epoxystearic acid (0.7%)]. The fatty acids have been analyzed by gas chromatography/mass spectrometry of their methyl ester and 4,4-dimethyloxazoline derivatives. The hydroxy fatty acid methyl esters have been examined also as trimethyl-silyl ethers. Furthermore, the fatty acid methyl esters (FAME) have been fractionated according to their polarity (FAME-A: nonhydroxy; FAME-B: hydroxy fatty acids) and to their degree of unsaturation (FAME-A1/A2; FAME-B1/B2) by preparative thin-layer chromatography and argentation chromatography, respectively. All of these fractions have been analyzed by ultraviolet and infrared spectroscopy, and the fractions FAME-A and FAME-B have been analyzed further by nuclear magnetic resonance (¹H,¹³C, 2D H/C, attached proton test) spectroscopy and gas chromatography/mass spectrometry. This work is dedicated to the 65th birthday of Prof. Dr. K. Pfeilsticker, Institut of Food Science, University Bonn (Germany).     

超临界辅助雾化法制备壳聚糖/薰衣草精油颗粒

为了探索得到可用于芳香纤维用的芳香超细颗粒,采用了以壳聚糖/薰衣草精油为一相,CO<,2>为另一相通过喷嘴雾化(SAA)法制备出壳聚糖/薰农草精油超细颗粒,考察了物料配比、预膨胀压力、预膨胀温度和溶液流率等工艺参数对所制备的颗粒形貌和粒径的影响;并对颗粒释放的气味进行气相色谱表征,以进行颗粒留香时间的考察.结果表明:降...     

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%.     

Method for characterization of triacylglycerols and fat-soluble vitamins in edible oils and fats by supercritical fluid chromatography

This study demonstrates the usefulness of capillary supercritical fluid chromatography (SFC) for the characterization of triacylglycerols of edible oils and fats. Triacylglycerols were separated according to the acyl carbon number and the degree of unsaturation on a 25% cyanopropyl/25% phenyl/50% methylpolysiloxane stationary phase. Valuable information concerning the triacylglycerol composition of berry oils was obtained, despite the overlapping of certain triacylglycerol peaks. Simultaneous analysis of fat-soluble vitamins and triacylglycerols is not practical by capillary SFC with flame-ionization detection because of the low concentration of naturally-occurring fat-soluble vitamins in edible oils. Therefore, higher loading of the sample, which led to overloading of triacylglycerols, was required to get reasonable peaks for fat-soluble vitamins. The method was applied to the characterization of triacylglycerols and tocopherols in sea buckthorn pulp and seed oil, and cloudberry seed oil without any sample purification prior to SFC. In addition, the stationary phase proved useful for separating the more complex mixtures of triacylglycerols found in milk fat and in fish oil.     

Triacylglycerol composition of Pinus koraiensis seed oil

The triacylglycerol (TG) composition of Pinus koraiensis seed oil, which contains Δ5 nonmethylene-interrupted (NMI) fatty acids (FA) (the main acid is pinolenic, 18:3 Δ5, 9, 12), was determined. TG were preliminarily separated by argentation thin-layer chromatography (TLC), and the obtained fractions were analyzed by high-temperature gas chromatography (GC) on a capillary column with methyl phenyl silicone phase. Additionally, high-performance liquid chromatography (HPLC) of TG was applied. The FA composition of all TG fractions was identified. The identification of TG was carried out by combining TLC, GC, HPLC, and calculated equivalent carbon numbers of TG standards. The TG species identification was confirmed by comparison of the theoretical recalculated and directly analyzed FA compositions of all TLC fractions of TG. Species of TG with unsaturation degrees of 1 to 7 and trace amounts of saturated and octaenoic TG species were found. Except for minor compounds, 26 TG molecular species of 32 main components were quantitatively determined. The main species were oleoyl dilinoleoylglycerol (14.7%), dilinoleoyl pinolenoylglycerol (10.7%), palmitoyl oleoyl linoleoylglycerol (8.3%), triolein (7.6%), and dioleoyl, linoleoylglycerol (7.4%). Seven TG species contained Δ5 NMI acyl groups. Of these, the major were dilinoleoyl pinolenoyglycerol (10.7%), stearoyl linoleoyl pinolenoylglycerol (6.5%) dioleoyl, pinolenoylglycerol (5.4%), and palmitoyl linoleoyl pinolenoyl-glycerol (5.5%). TG species with two or three NMI acyl groups were not detected.     

Analysis of the wax ester fraction of olive oil and sunflower oil by gas chromatography and gas chromatography-mass spectrometry

The wax ester fractions of solvent-extracted sunflower oil and “extra virgin” olive oil were obtained by solid-phase extraction and subsequently subjected to gas-chromatographic and gas chromatographic-mass spectrometric analysis. The comprehensive qualitative analysis of these fractions, which was carried out by the interpretation of mass spectral data, revealed several types of wax esters. In olive oil, shortchain, even-numbered wax esters, saturated and unsaturated long-chain, even-numbered wax esters, benzyl esters, and the diterpenic esters phytyl and geranylgeranyl ester (the latter as a minor component) are present. With the exception of benzyl esters, all these esters occur in sunflower oil as well, but in considerably different amounts compared to those in olive oil. Whereas unsaturated wax esters are present in a negligible amount, diterpenic esters, mainly geranylgeranyl esters, represent the major part of the wax ester fraction.     

Extraction of lipid-grown bacterial cells by supercritical fluid and organic solvent to obtain pure medium chain-length polyhydroxyalkanoates

A simple two-step process was developed to extract and purify medium chain-length polyhydroxyalkanoates (MCL-PHA) from bacterial cells (Pseudomonas resinovorans) grown on lard and tallow. The process consists of supercritical fluid extraction (SFE) of the lyophilized cells with carbon dioxide to remove lipid impurities, followed by chloroform extraction of the cells to recover the MCL-PHA. SFE conditions were varied as to temperature (40–100°C), pressure (2000–9000 psi), and carbon dioxide flow rate (0.5–1.5 L/min, expanded gas). Lipid material, usually 2–4%, but in some cases as high as 11%, was extracted from the dried cells by SFE. A pressure range (5000–9000 psi, increased stepwise), a temperature of 60°C, and a carbon dioxide flow of 1.5 L/min were routinely used to extract the bacterial cells (4–5 g) after 3 h. Higher flow rates could shorten the extraction time even more. SFE did not extract MCL-PHA from the cells. Yield of MCL-PHA after chloroform extraction at room temperature was a maximum of 42.4% based on dry cell weight. The results show that the two-step process saves time, uses much less organic solvent, and produces a purer MCL-PHA biopolymer than previous extraction and purification methods. A more environmentally friendly clean-up procedure based on SFE and organic solvent recovery was developed to remove contaminating lipid materials from the fermentation biomass, allowing for the recovery of higher purity MCL-PHA that are suitable for more demanding applications.     

Analysis of C18:1 cis and trans fatty acid isomers by the combination of gas-liquid chromatography of 4,4-dimethyloxazoline derivatives and methyl esters

Trans fatty acids in foods are usually analyzed by gas-liquid chromatography (GLC) of fatty acid methyl esters (FAME). However, this method may produce erroneously low values because of insufficient separation between cis and trans isomers. Separation can be optimized by preceding silver-ion thin-layer chromatography (Ag-TLC), but this is laborious. We have developed an efficient method for the separation of 18-carbon trans fatty acid isomers by combining GLC of FAME with GLC of fatty acid 4,4-dimethyloxazoline (DMOX) derivatives. We validated this method against conventional GLC of FAME, with and without preceding Ag-TLC. Fatty acid isomers were identified by comparison with standards, based on retention times and mass spectrometry. Analysis of DMOX derivatives allowed the 13t, 14t, and 15t isomers to be separated from the cis isomers. The combination of the GLC analyses of FAME and DMOX derivatives gave results comparable with those obtained by GLC of FAME after preceding Ag-TLC, while saving about 100 h of manpower per 25 samples. It allowed the identification and quantitation of 11 trans and 8 cis isomers and resulted in 25% higher values for total C_18:1 trans, compared with the analysis of FAME alone. The combination of DMOX and FAME analyses, as applied to the analysis of 14 foods that contained ruminant fat and partially hydrogenated vegetable and fish oils, indicated that the most common isomers were 11t in ruminant fats, 9t in partially hydrogenated fish fats, and either 9t or 10t in partially hydrogenated vegetable fats. The combination of GLC analyses of FAME and DMOX derivatives of fatty acids improves the quantitation of 18-carbon fatty acid isomers and may replace the laborious and time-consuming Ag-TLC.     

Quantification of linolenic acid isomers by gas chromatography‐mass spectrometry and deconvolution of overlapping chromatographic peaks

The use of a technique for deconvolution of overlapping chromatographic peaks, Gentle, has been evaluated for quantification of alpha linolenic acid isomers analysed by gas chromatography‐mass spectrometry. Mixtures containing varying amounts of linolenic acid methyl ester isomers with two or three trans double bonds were analysed by two different temperature programs. Overlapping chromatographic peaks were resolved by Gentle, and the areas of the resolved peaks were compared with reference values calculated by use of internal standards. The results show that the small differences that exist between the mass spectra of the analysed isomers are sufficient to achieve deconvolution of severely overlapping peaks. The errors were larger than seen for quantification of chromatographically resolved peaks. Especially for small peaks in a peak cluster, the errors relative to the peak size were large.     

Characterization of chilean hazelnut (Gevuina avellana mol) seed oil

The fatty acid composition, tocopherol and tocotrienol content, and oxidative stability of petroleum benzene-extracted Gevuina avellana Mol (Proteaceae) seed oil were determined. Positional isomers of monounsaturated fatty acids were elucidated by gas chromatography-electron impact mass spectrometry after 2-alkenyl-4,4-dimethyloxazoline derivatization. This stable oil (Rancimat induction period at 110°C: 20 h) is composed of more than 85% monounsaturated fatty acids and about equal amounts (6%) of saturated and polyunsaturated (principally linoleic) fatty acids. Unusual positional isomers of monounsaturated fatty acids, i.e., C_16:1 Δ¹¹, C_18:1 Δ¹², C_20:1 Δ¹¹, C_20:1 Δ¹⁵, C_22:1 Δ¹⁷, and presumably C_22:1 Δ¹⁹ were identified. The C_18:1 Δ¹² and C_22:1 Δ¹⁹ fatty acids are described for the first time in G. avellana seed oil. While only minute quantities of α-, γ-tocopherols and β-, γ- and δ-tocotrienols were found, the oil contained a substantial amount of α-tocotrienol (130 mg/kg). The potential nutritional value of G. avellana seed oil is discussed on the basis of its composition.     

Supercritical fluid chromatographic analysis of new crop seed oils and their reactions

Supercritical fluid chromatography (SFC) with an open tubular column of nonpolar stationary phase separated triglycerides from crambe, meadowfoam,Euphorbia lagascae, and vernonia oils based on their molecular weight. The triglyceride compositions were consistent with the literature. SFC proved also to be a valuable tool in analyzing lipase-catalyzed transesterification reactions where lesquerella oil and estolides were among the substrates employed. Analyte molecular weights could be estimated from a retention time- (or elution density-) molecular eeight calibration curve. An increase in isothermal column temperature during SFC pressure or density programming improved the resolution of high-molecular-weight (>600 Da) analytes but yielded poorer resolution for analytes of molecular weight <200. A simultaneous pressure and temperature ramping program proved superior in enhancing resolution in several instances. Presented at the AOCS Annual Meeting & Expo, May 1995, San Antonio, Texas. Retired     

Separation and identification of ximenynic acid isomers in the seed oil ofSantalum spicatum R.Br. as their 4,4-dimethyloxazoline derivatives

The seed oil ofSantalum spicatum contains a significant amount of ximenynic acid,trans-11-octadecen-9-ynoic acid, a long-chain acetylenic fatty acid, as a major component (34%). The identity oftrans-ximenynic acid was confirmed after isolation by ultraviolet, infrared, and nuclear magnetic resonance (NMR) (¹H- and¹³C-) spectroscopy and by gas chromatography/mass spectrometry (GC/MS). Thecis isomer of ximenynic acid was also found (<1%) in some samples. Thecis andtrans isomers were characterized by GC/MS comparison of their methyl esters and 4,4-dimethyloxazoline derivatives.     

Determination of petroselinic acid inUmbelliflorae seed oils by combined GC and13C NMR spectroscopy analysis

Synthetic triolein and tripetroselinin mixtures were examined by¹³C NMR spectroscopy, showing marked chemical shift differences of the olefinic carbon atoms. Peak height ratios were compared to weight values for quantitative determination of oleic and petroselinic acids in seed oils, since these two fatty acids are quantitated together by GC analysis. Values observed for NMR peak height ratios were fairly close and agreed well with weight ratios. From overall compositions of eleic and petroselinic acids obtained by GC and relative compositions given by¹³C NMR, petroselinic acid has been determined in tenUmbelliflorae seed oils.