The seed oil ofBernardia pulchella (Euphorbiaceae) —A rich source of vernolic acid

The fatty acids from the seed oil ofBernardia pulchella (Euphorbiaceae) have been analyzed by gas chromatography (GC) and GC-mass spectrometry (MS) analysis of their methyl esters. Vernolic acid is the main compound (91%), along with other usual fatty acids. In addition to the quantitation by GC analysis,¹H-nuclear magnetic resonance (NMR) signals from the seed oil have been used to estimate the total epoxy fatty acid content. The structure of vernolic acid has been proven by spectroscopic methods (infrared,¹H, and¹³C-NMR) and by GC-MS analysis of the corresponding silylated hydroxy-methoxy derivative. The 4,4-dimethyloxazoline derivatives of the fatty acid mixture have also been examined by GC-MS, and it was shown that this derivazation reaction is not suitable for the structure analysis of vernolic acid.     

Analysis of seed oil from ricinus communis and dimorphoteca pluvialis by gas and supercritical fluid chromatography

The seed oils from Dimorphoteca pluvialis and Ricinus communis contain hydroxy fatty acids. Dimorphoteca pluvialis contains Δ-9-hydroxy-10t, 12t-octadecadienoic acid (dimorphecolic acid) and R. communis contains Δ-12-hydroxy-9c-octadecenoic acid (ricinoleic acid). The oils were derivatized and analyzed to determine the content of hydroxy fatty acids. The trimethylsilyl fatty acid methyl ester (TMS-FAME) derivatives were analyzed by capillary gas chromatography (GC), and the free fatty acid (FFA) derivatives and the oils were analyzed by capillary supercritical fluid chromatography (SFC). Further, mass spectroscopy of the TMS-FAME derivatives was performed to check the purity of the derivatives. The results from the GC analyses of TMS-FAME corresponded to the results found by SFC analysis of the FFA. The content of ricinoleic acid in the glycerolipids of R. communis was 87.7 wt%, and the content of dimorphecolic acid in D. pluvialis was 54.0 wt%. The methods were evaluated with respect to the cost, ease, and time needed for sample preparation and analysis.     

High-performance liquid chromatography of the triacylglycerols ofVernonia galamensis andCrepis alpina seed oils

The triacylglycerols ofVernonia galamensis andCrepis alpina seed oils were characterized because these oils have high concentrations of vernolic (cis-12,13-epoxy-cis-9-octadecenoic) and crepenynic (cis-9-octadecen-12-ynoic) acids, respectively. The triacylglycerols were separated from other components of crude oils by solid-phase extraction, followed by resolution and quantitation of the individual triacylglycerols by reversed-phase high-performance liquid chromatography with an acetonitrile/methylene chloride gradient and flame-ionization detection. Isolated triacylglycerols were characterized by proton and carbon nuclear magnetic resonance and by capillary gas chromatography of their fatty acid methyl esters. The locations of the fatty acids on the glycerol moieties in the oils were obtained by lipolysis. TheVernonia galamensis oil contained 50% trivernoloyl and 21% divernoloyllinoleoyl glycerols along with 20% triacylglycerols with one vernolic and two other fatty acids. TheCrepis alpina oil contained 36% tricrepenynoyl and 33% dicrepenynoyllinoleoyl glycerols, 17% triacylglycerols with two crepenynic and one other fatty acid and 7% triacylglycerols with one crepenynic acid and two other fatty acids. Vernolic acid was found at both the 1(3)- and 2-glycerol carbons but was more abundant at the 1,(3)-position in theVernonia galamensis oil. Crepenynic acid was found at both glycerol carbon positions but was more abundant at the 2-position in theCrepis alpina oil. Visiting scientist from Technical Research Institute, Snow Brand Milk Company, Ltd., Saitana, Japan.     

A minor source of vernolic,malvalic, and sterculic acids inPithecollobium dulce (syn.Inga dulcis) seed oil

Pithecollobium dulce, Benth (syn.Inga dulcis, Willd) seed oil, belonging to the Leguminosae plant family, contains minor amounts of vernolic acid (12,13-epoxy-octadec-cis-9-enoic acid, 10.0%), malvalic acid [7-(2-octacyclopropen-1-yl)heptanoic acid, 3.2%], and sterculic acid [8-(2-octacyclopropen-1-yl)octanoic acid, 2.0%]. The other normal fatty acids are palmitic (12.1%), stearic (4.2%), behenic (10.6%), oleic (34.1%), and linoleic (23.8%). These fatty acids have been characterized by Fourier transform infrared,¹H nuclear magnetic resonance, mass spectrometry and gas-liquid chromatography techniques and by chemical degradations.     

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.     

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.     

Comparative study of the extraction and measurement of cottonseed free fatty acids

Crude oil was extracted from cottonseed by three different methods to study the influence of extraction technique on the free fatty acid (FFA) concentration. Extraction procedures that recovered more oil had higher levels of FFA. In addition, the highest concentration of FFA was found in oil recovered by Soxhlet reextraction of a meal initially defatted by a room-temperature extraction process. The FFA concentrations of oils recovered by Soxhlet extraction were highly correlated with the FFA concentration of oils recovered by the other extraction methods studied (R ²>0.96). Titration of oil and gas chromatography of silylated oil were compared as methods to determine FFA concentration. The methods compared well (R ²=0.998) with the titration method, giving ∼5% higher values for FFA than the chromatography method. Half of this difference appeared to be due to the oleic acid approximation used in the titration approach. The other half of the difference is likely due to the detection of other acidic components in crude oil.     

Kigelia pinnata Seed Oil – A Moderate Source of Vernolic Acid

Vernolic acid represents 22.3% of the constituent fatty acids of the speed oil of an additional hitherto unexamined species of Bignoniaceae Kigelia pinnata. Its identification is based on comparative informations from thin-layer chromatography, infrared analysis, gas liquid chromatography and nuclear magnetic resonance spectroscopy with that of reference sample of Vernonia anthelmintica seed oil. The other fatty acids in this oil are: 14:0 (0.4), 16:0 (25.4), 18:0(0.9), 18:1 (8.9) and 18:2 (42.0%). K. pinnata is the first species of Bignoniaceae to be reported to contain vernolic acid in moderate amount.     

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.     

Supercritical fluid chromatographic analysis of fish oils

Various natural and processed fish oil triglyceride mixtures have been analyzed by capillary supercritical fluid chromatography (SFC). The analyses were performed on nonpolar columns to separate the components by lipid class and by the number of carbon atoms. The compounds separated included free fatty acids, squalene, α-tocopherol, cholesterol, wax esters, cholesteryl esters, di- and triglycerides. This kind of analysis is not possible by gas chromatography or high-performance liquid chromatography methods without prior treatment of the fish oil, making SFC superior for this application. Applications of SFC to fish oils are given, including a control analysis of the various process steps in the refining of a fish oil, analysis of a lipase-catalyzed transesterification of a fish oil and the detection of polymeric artifacts.     

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.     

Vernonia volkameriaefolia Seed oil: a rich source of epoxy acid

The seeds ofVernonia volkameriaefolia contain 20% oil and are a good source of epoxidized triglycerides. The vernolic acid (cis-12, 13-epoxy-cis-9, 10-octadecenoic acid) content of the oil was 63.5%. The structure of this compound was established by chemical and physical methods, including a study of the mass spectral fragmentation of the parent compound and its derivatives.     

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).     

Isolation of Non-methylene Interrupted or Acetylenic Fatty Acids from Seed Oils Using Semi-preparative Supercritical Chromatography

Preparative scale supercritical fluid chromatography was used for isolating and purifying uncommon non-methylene interrupted or acetylenic polyunsaturated fatty acids ethyl esters from seed oils. Fractionation of Biota orientalis seed oil ethyl esters was performed by supercritical fluid chromatography to obtain juniperonic acid [(5Z,11Z,14Z,17Z)-eicosa-5,11,14,17-tetraenoic acid], a non-methylene interrupted polyunsaturated fatty acid. Fractionation of sandalwood seed oil ethyl esters yielded ximenynic acid [(E)-octadec-11-en-9-ynoic acid], an acetylenic polyunsaturated fatty acid. The effects of CO₂ flow rate, column stationary phase and particle size were explored to optimize ximenynic and juniperonic ethyl ester recovery and purity from ethyl ester mixtures using online UV/Vis detection. Particle size, followed by the stationary phase, were found to be the most important parameters to achieving good separation. Under optimized conditions, ximenynic and juniperonic ethyl ester purities greater than 99 and 95%, respectively, were achieved in a one step process without co-solvent. The isolation and recovery of juniperonic acid from biota seed oil free fatty acids was also attempted. Using free fatty acids as the feed material, the non-methylene interrupted polyunsaturated sciadonic acid was also able to be separated from other compounds including juniperonic acid under some conditions, and gave an increase in concentration of more than 17 times.     

Hibiscus mutabilis Seed Oil – Characterization of HBr-Reactive Acids

The seed oil of Hibiscus mutabilis (Chameleon rose) (Malvaceae) contains three HBr-reactive fatty acids. These are found to be cis-12, 13-epoxyoleic (vernolic) acid, 5.9%; 9,10-methylene-octadec-9-enoic (sterculic) acid. 7.3%; as well as 8,9-methylene-heptadec-8-enoic (malvalic) acid, 14.0%. Co-occurrence of these acids was established by combined spectroscopie, chromatographic and chemical techniques.     

Heated fat-based oil substitutes, oleic and linoleic acid-esterified propoxylated glycerol

Four oils [triolein, trilinolein, oleic acid-esterified propoxylated glycerol (EPG-08 oleate), and linoleic acid-esterified propoxylated glycerol (EPG-08 linoleate)], each without added antioxidants, were heated for 12 h/d at approximately 190°C in a small deep-fat fryer until the polymer concentration exceeded 20%, as determined by high-performance size-exclusion chromatography. Increases in the free fatty acid content, total acid value, food oil sensor value, and p-anisidine value during heating indicated that significant thermal oxidation had occurred in each oil. Capillary supercritical fluid chromatography (SFC) was used to determine the substrate concentration of each oil after each heating interval. The average, apparent first-order reaction rate constant (as determined by SFC) for trilinolein was 0.0348±0.0034 h⁻¹, while the rate for EPG-08 linoleate was 0.0253±0.0032 h⁻¹. The average apparent reaction rate constant for triolein was 0.0256±0.0011 h⁻¹, while the rate for EPG-08 oleate was 0.0252±0.0008 h⁻¹. Triolein contained >20% polymer after 60 h of heating, EPG-08 oleate contained >20% polymer after 36 h of heating, and both trilinolein and EPG-08 linoleate contained >20% polymer after 24 h of heating.     

Naturally occurring epoxy acids. IV. The absolute optical configuration of vernolic acid

Vernolic acid [(+)-cis-12,13-epoxyleic acid] was transformed by stereospecific reactions to a mixture ofthreo-9,10,12-andthreo-9,10,13-trihydroxyoctadecanols. The four components of this mixture were separately isolated by chromatography on thin layers impregnated with glycol-complexing agents. The 9,10,12-trihydroxyoctadecanols so obtained were identical to the corresponding derivatives of D-(+)-ricinoleic acid, thereby proving the absolute optical configuration of the epoxy group of vernolic acid to be D. As a corollary to this the absolute configurations of some other oxygenated fatty acids have been deduced.     

Lipase-catalyzed incorporation of oleic acid into melon seed oil

The ability of lipase PS30 (Pseudomonas sp.) to modify the fatty acid profile of melon seed oil by incorporation of oleic acid (18:1n-9) was investigated. The transesterification was carried out in hexane in an orbital shaking water bath at 55°C for 24 h with methyl oleate (70% pure) as acyl donor. Oleic acid content increased from 13.5% to 53%, and linoleic acid (18:2n-6) content decreased from 65% to 33%. The incorporation of oleic acid into melon seed oil by Pseudomonas sp. lipase helped balance the fatty acid profile of the oil in terms of monounsaturated (18:1n-9) and essential fatty acids (18:2n-6).     

Simultaneous Determination of Free Fatty Acids and Esterified Fatty Acids in Rice Oil by Gas Chromatography

Free fatty acids (FFA) in crude rice oil were selectively and stoichiometrically derivatized to fatty acid N,N-dimethylamides (FADMA) by catalytic condensation at 45 °C, and then esterified fatty acids (eFA) were directly converted to fatty acid methyl esters (FAME) at 37 °C. The mixture of FADMA and FAME formed in a single test tube was injected into the capillary column of a gas chromatograph (GC). No mutual contamination occurred between FFA and eFA, and reliability of the method was confirmed by comparison between GC data obtained by this method and by a conventional isolation method. The advantages of the present method are that no FFA isolation procedures are required, the reactions proceed under mild temperature conditions, and FFA and eFA can be analyzed simultaneously by GC.     

Trans fatty acid composition and tocopherol content in vegetable oils produced in Mexico

The purpose of this study was to evaluate the trans fatty acid (TFA) composition and the tocopherol content in vegetable oils produced in Mexico. Sample oils were obtained from 18 different oil refining factories, which represent 72% of the total refineries in Mexico. Fatty acids and TFA isomers were determined by gas chromatography using a 100-m fused-silica capillary column (SP-2560). Tocopherol content was quantified by normal-phase high-performance liquid chromatography using an ultraviolet detector and a LiChrosorb Si60 column (25 cm). Results showed that 83% of the samples corresponded to soybean oil. Seventy-two percent of the oils analyzed showed TFA content higher than 1%. Upon comparing the tocopherol contents in some crude oils to their corresponding deodorized samples, a loss of 40–56% was found. The processing conditions should be carefully evaluated in order to reduce the loss of tocopherols and the formation of TFA during refining.