Fatty acid esters of glycidol in refined fats and oils

Discrepancies in the analysis of 3‐chloropropane‐1,2‐diol (3‐MCPD) esters can be explained by the hypothesis that in some refined oils significant amounts of fatty acid esters of glycidol (glycidyl esters) are present in addition to 3‐MCPD esters. Glycidyl esters were separated from triacylglycerols by gel permeation chromatography (GPC) and detected by gas chromatography‐mass spectrometry (GC‐MS). Six samples of palm oil and palm oil‐based fats were analyzed by GPC and GC‐MS. In chromatograms of all samples, significant peaks, retention time and mass spectra in conformity with self‐synthesized glycidyl palmitate and glycidyl oleate were detectable. Quantification of individual glycidyl esters was not possible because of a lack of pure standards. Concentration of ester‐bound glycidol in different samples of fats and oils was estimated using an indirect difference method. Glycidyl esters could be detected only in refined, but not in crude or native, fats and oils. The highest concentrations were detected in palm oil and palm oil‐based fats. In a palm oil sample, glycidyl ester concentration varied according to different deodorization parameters, temperature, and time, while 3‐MCPD ester concentration was relatively constant, indicating that mitigation of glycidyl esters possibly may be achieved by optimizing refining parameters.     

Separation of the Fatty Acids in Menhaden Oil as Methyl Esters with a Highly Polar Ionic Liquid Gas Chromatographic Column and Identification by Time of Flight Mass spectrometry

The fatty acids contained in marine oils or products are traditionally analyzed by gas chromatography using capillary columns coated with polyethylene glycol phases. Recent reports indicate that 100 % cyanopropyl siloxane phases should also be used when the analyzed samples contain trans fatty acids. We investigated the separation of the fatty acid methyl esters prepared from menhaden oil using the more polar SLB-IL111 (200 m × 0.25 mm) ionic liquid capillary column and the chromatographic conditions previously optimized for the separation of the complex mixture of fatty acid methyl esters prepared from milk fat. Identifications of fatty acids were achieved by applying Ag⁺-HPLC fractionation and GC-TOF/MS analysis in CI⁺ mode with isobutane as the ionization reagent. Calculation of equivalent chain lengths confirmed the assignment of double bond positions. This methodology allowed the identification of 125 fatty acids in menhaden oil, including isoprenoid and furanoid fatty acids, and the novel 7-methyl-6-hexadecenoic and 7-methyl-6-octadecenoic fatty acids. The chromatographic conditions applied in this study showed the potential of separating in a single 90-min analysis, among others, the short chain and trans fatty acids contained in dairy products, and the polyunsaturated fatty acids contained in marine products.     

The Effect of Type of Oil and Degree of Degradation on Glycidyl Esters Content During the Frying of French Fries

The aim of the study was to determine the effect of oil degradation on the content of glycidyl esters (GEs) in oils used for the frying of French fries. As frying media, refined oils such as rapeseed, palm, palm olein and blend were used. French fries were fried for 40 h in oils heated to 180 °C in 30‐min cycles. After every 8 h of frying, fresh oil and samples were analyzed for acid and anisidine values, color, refractive index, fatty acid composition, and content and composition of the polar fraction. GEs were determined by LC–MS. Hydrolysis and polymerization occurred most intensively in palm olein, while oxidation was reported for rapeseed oil. The degradation of oil caused increased changes in the RI of frying oils. Losses of mono‐ and polyunsaturated fatty acids were observed in all samples, with the largest share in blend. The highest content of GE found in fresh oil was in palm olein (25 mg kg^?1) and the lowest content of GE was found in rapeseed oil (0.8 mg kg^?1). The palm oil, palm olein and blend were dominated by GEs of palmitic and oleic acids, while rapeseed oil was dominated by GE of oleic acid. With increasing frying time, the content of GEs decreased with losses from 47 % in rapeseed oil to 78 % in palm oil after finishing frying.     

Antioxidant activity of evening primrose phenolics in sunflower and rapeseed oils

Crude ethanol/ethyl acetate extracts of industrial evening primrose (Oenothera biennis L.) seed meal were separated into six fractions using the Sephadex LH‐20 column chromatography and 96% aqueous ethanol as a mobile phase. Their antioxidant activities were tested in sunflower and rapeseed oils by using an Oxidograph apparatus at a temperature of 110 °C. Only the fractions III and IV displayed a pronounced antioxidant activity while the other fractions were either inactive or even pro‐oxidative. The active fractions contained phenolic acids and their esters; gallic acid, methyl and ethyl gallates, protocatechuic acid and its methyl ester were identified by GC/MS. Catechin was present, too, but exhibited only moderate antioxidant activity in sunflower oil.     

Wax ester fraction of edible oils: Analysis by on‐line LC‐GC‐MS and GC×GC‐FID

The wax ester fraction of various plant oils was isolated by normal‐phase HPLC (NPLC) on‐line coupled to GC via the on‐column interface and applying concurrent eluent evaporation. The esters were analyzed by on‐line NPLC‐GC‐MS and by comprehensive two‐dimensional GC with flame ionization detection (GC×GC‐FID) off‐line combined with NPLC‐GC. GC×GC‐FID enables to group the various classes of wax esters, in particular the phytol esters, geranylgeraniol esters and the straight‐chain esters of palmitic acids and the unsaturated C₁₈ acids. Optimization of the GC×GC columns and the conditions must take into account the limited thermostability of the diterpene esters. Chromatograms are shown for a range of oils, with particular focus on the various classes of wax esters in olive oil and the geranylgeraniol esters 22:0 and 24:0 in a variety of oils.     

Screening vegetable oil alcohol esters as fuel lubricity enhancers

Methyl and ethyl monoalkyl esters of various vegetable oils were produced for determining the effects of type of alcohol and fatty acid profile of the vegetable oil on the lubricity of the ester. Four methyl esters and six ethyl esters were analyzed for wear properties using the American Society for Testing and Materials method D 6079, Evaluating Lubricity of Diesel Fuels by the High-Frequency Reciprocating Rig. Ethyl esters showed noticeable improvement compared to methyl esters in the wear properties of each ester tested. No correlation was found between lubricity improvement and fatty acid profile of the ester, except that esters of castor oil had improved lubricity over other oils with similar carbon chain-length (C₁₈) fatty acids.     

Chemoenzymatic epoxidation of unsaturated fatty acid esters and plant oils

In the presence of an immobilized lipase fromCandida antacrtica (Novozym 435^R) fatty acids are converted to peroxy acids by the reaction with hydrogen peroxide. In a similar reaction, fatty acid esters are perhydrolyzed to peroxy acids. Unsaturated fatty acid esters subsequently epoxidize themselves, and in this way epoxidized plant oils can be prepared with good yields (rapeseed oil 91%, sunflower oil 88%, linseed oil 80%). The hydrolysis of the plant oil to mono- and diglycerides can be suppressed by the addition of a small amount of free fatty acids. Rapeseed oil methyl ester can also be epoxidized; the conversion of C=C-bonds is 95%, and the composition of the epoxy fatty acid methyl esters corresponds to the composition of the unsaturated methyl esters in the substrate. Based partly on a lecture at the 86th AOCS Annual Meeting & Expo, San Antonio, Texas, May 7–11, 1995.     

Zu den Veränderungen von Rapsöl und Leinöl während der Verarbeitung

Changes of rapeseed and linseed oil during processing During processing of crude oil in a large oil mill, three samples each of rapeseed and linseed were investigated at each processing stage, i.e. press oil, solvent-extracted oil, mixed oil, and degummed/caustic refined oil. In the case of rapeseed also bleached and desodorized oils (230°C; 3.0 mbar for 2 h) were investigated. Rapeseed and linseed oil showing the typical major fatty acids contained less than 1% trans-isomeric fatty acids (trans fatty acids = TFA). Linseed oil had a similar TFA-concentration as rapeseed oil, and the concentrations did not change during the processing stages up to degummed/caustic refined oil, and were also unchanged in the bleached rapeseed oil. Desodorization of rapeseed oil, however, trebled the TFA concentration to 0.58%. The detected tocopherol patterns were typical of rapeseed and linseed oils. There was no difference between mixed oil and degummed/caustic refined oil in the total concentration of tocopherols. Neither had bleaching any effect. Rapeseed oil desodorization diminished total tocopherol concentration by 12% from 740 mg/kg to 650 mg/kg. Due to degumming/caustic refining the phosphorus concentration of both oils decreased to less than a tenth compared to mixed oil. Other elements determined in degummed/caustic refined rapeseed oil were not detectable (manganese < 0.02 mg/kg, iron < 0.4 mg/kg, copper < 0.02 mg/kg, lead < 10 μg/kg) or only as traces zink 0.1 mg/kg, cadmium 2 μg/kg). In linseed oil, which initially showed a higher trace compounds concentration, a significant decrease was found by degumming/caustic refining. Iron could not be detected. There were traces of zinc, manganese, copper, lead, and cadmium. There was no difference between the acid values of rapeseed and linseed crude oil. Acid value decreased drastically already during the degumming/caustic refining stage. The crude linseed oils had a higher peroxide value, anisidine value and diene value than the corresponding crude rapeseed oils. With peroxide values of ≤ 0.1 mEq O₂/kg found in almost all investigated rapeseed oils, no effect of refining could be detected. The anisidine value showed an increase after bleaching. Desodorization trebled the diene value.     

Fatty acid composition of carotenoid esters in soybean and rapeseed oils

The amounts of the different carotenoids (lutein, lutein monoesters and diesters) in soybean and rapeseed oil were determined through a combination of column chromatography and UV spectrometry. The lutein diesters in the oils have been isolated by a combination of column and thin layer chromatography. Identification and determination of the amount of the various fatty acids of the lutein diesters have been carried out by means of gas chromatography after transesterification of the fatty acids to their methyl esters. Comparison of the fatty acids of the lutein diesters with those of the triglycerides of the oils revealed a striking difference. First, the fatty acids of the lutein diesters have shorter chains than the triglycerides acids. Secondly, the lutein fatty acids are more saturated than the fatty acids of the triglycerides of the corresponding oils. However the amount of linoleic acid in the case of the fatty acids of the lutein diesters in rapeseed oil is greater than that in the fatty acids of the triglycerides in rapeseed oil. Deceased, October 26, 1971.     

Evaluation of the Triglyceride Composition of Pomegranate Seed Oil by RP‐HPLC Followed by GC‐MS

Triglyceride composition and fatty acid profiles of pomegranate seed oil were evaluated by newly developed methods in reverse‐phase‐high performance liquid chromatography (RP‐HPLC) and gas chromatography (GC), respectively. Different compositions of the mobile phase (acetone and acetonitrile) and flow rates for the HPLC system were used to obtain better separation for accurate quantitative analysis. Triglycerides with conjugated fatty acids (CLnAs) were eluted in order of the polarity of their geometrical isomers (c, t, c < t, t, c < t, t, t). The dominant triglyceride was found to be PuPuPu (32.99 %) in pomegranate seed oil, followed by PuPuCa and PuCaCa containing punicic acid and catalpic acid with total triglyceridelevels of 27.72 and 10.11 %, respectively. For fatty acid composition analysis, triglyceride fractions were derivatized into their respective methylesters which were injected into gas chromatography‐mass spectrometry (GC‐MS) to identify and gas chromatography‐flame ionization detector (GC‐FID) to quantify the conjugated fatty acids of each fraction of triglycerides. Punicic acid was found to be dominant (76.57 %) followed by catalpic acid (6.47 %) and β‐eleotearic acid (1.45 %). Pomegranate seed contained greater amounts of conjugated linolenic acids. These results showed that the present study provides more information about the composition of the triglyceride and fatty acid profiles of pomegranate seed oil compared to the reported studies. Therefore, the developed methods in this study can be used for the identification of the triglyceride and fatty acid composition for pomegranate seed oils and some such specials edible oils including CLnA isomers.     

Detection of 430 Fatty Acid Methyl Esters from a Transesterified Butter Sample

Milk fat is known to contain one of the highest number of fatty acids of all edible oils. Some of these fatty acids are known to be valuable (e.g. conjugated linoleic acids, furan fatty acid) and other as undesirable (e.g. saturated and some trans-fatty acids) food ingredients. However, a comprehensive picture on the presence of many trace fatty acids has not been achieved. For this reason we have developed an analysis scheme based on the conversion of the fatty acids into methyl esters. The fatty acid methyl esters were then fractionated by urea complexation. Both the filtrate of the urea complexation (~4 % of the sample weight) and the original sample were fractionated by high-speed counter-current chromatography (HSCCC). The resulting fractions were analyzed by GC/MS analysis. With this method 430 fatty acids were detected in one single butter sample. More than 230 fatty acids had two or more double bonds. In addition to the widely known spectrum of fatty acids we also detected a range of cyclohexyl fatty acids (five homologues) and methyl-branched fatty acids (including short chain and even-numbered anteiso-fatty acids), conjugated tetradecadienoic acids along with the novel ω-oxo-fatty acids (seven homologues). The reported relative retention time on the polar column may serve as a data base for the screening of other samples for this profusion of fatty acids.     

Analysis of hydroxylated fatty acids from plant oils

A novel process has been described recently for the preparation of hydroxylated fatty acids (HOFA) and HOFA methyl esters from plant oils. HOFA methyl esters prepared from conventional and alternative plant oils were characterized by various chromatographic methods (thin-layer chromatography, high-performance liquid chromatography, and gas chromatography) and gas chromatography-mass spectrometry as well as¹H and¹³C nuclear magnetic resonance spectroscopy. HOFA methyl esters obtained fromEuphorbia lathyris seed oil, low-erucic acid rapeseed oil, and sunflower oil contain as major constituents methylthreo-9,10-dihydroxy octadecanoate (derived from oleic acid) and methyl dihydroxy tetrahydrofuran octadecanoates, e.g., methyl 9,12-dihydroxy-10,13-epoxy octadecanoates and methyl 10,13-dihydroxy-9,12-epoxy octadecanoates (derived from linoleic acid). Other constituents detected in the products include methyl esters of saturated fatty acids (not epoxidized/derivatized) and traces of methyl esters of epoxy fatty acids (not hydrolyzed). The products that contain high levels of monomeric HOFA may find wide application in a variety of technical products.     

Survey of seed oils for use as diesel fuels

Fifty-one out of 364 plant seeds being surveyed had fatty acid contents greater than 15% (dry weight), and their methyl esters had cetane indices higher than 50. Rambutan seed was an exception, with a lipid content of only 14.7%, but a high cetane index (67.1); thus, it was included in this report. Twenty seed oil methyl esters had cetane indices greater than 60. Three seed oils from the Sapindaceae family not only had high cetane indices but also contained long-chain fatty acids of 20 carbon atoms. Gross heats of combustion of the fatty acid methyl esters were slightly higher than those of neat oil, ranging from 38.2 to 40.8 j/g, whereas the heating values of the oils ranged from 37.4 to 40.5 j/g. Thus, these plant seed oils have great potential for development as diesel fuel or diesel fuel extender.     

Nutritional studies of partially hydrogenated rapeseed oil

In three experiments rats were fed a purified basal diet with 20% by weight of partially hydrogenated rapeseed oil. One sample promoted, greater weight gains that the unhydrogenated oil. Another sample, containing a higher concentration of octadecadienoic acids other than 9,12-linoleic acid, produced the same response as the unhydrogenated material. With other samples of hydrogenated rapeseed oil, possessing less linoleic acid but other octadecadienoic acids, significantly lower weight gains were obtained. The alterations in the C₁₈ fatty acids resulting from hydrogenation of rapeseed oil appeared to be responsible for differing responses in weight gain.     

Improving the economics of biodiesel production through the use of low value lipids as feedstocks: vegetable oil soapstock

Semirefined and refined vegetable oils are the predominant feedstocks for the production of biodiesel. However, their relatively high costs render the resulting fuels unable to compete with petroleum-derived fuel. We have investigated the production of fatty acid methyl esters (FAME; biodiesel) from soapstock (SS), a byproduct of edible oil refining that is substantially less expensive than edible-grade refined oils. Multiple approaches were taken in search of a route to the production of fatty acid methyl esters from soybean soapstock. The most effective method involved the complete saponification of the soapstock followed by acidulation using methods similar to those presently employed in industry. This resulted in an acid oil with a free fatty acid (FFA) content greater than 90%. These fatty acids were efficiently converted to methyl esters by acid-catalyzed esterification. The fatty acid composition of the resulting ester product reflected that of soy soapstock and was largely similar to that of soybean oil. Following a simple washing protocol, this preparation met the established specifications for biodiesel of the American Society for Testing and Materials. Engine emissions and performance during operation on soy soapstock biodiesel were comparable to those on biodiesel from soy oil. An economic analysis suggested that the production cost of soapstock biodiesel would be approximately US$ 0.41/l, a 25% reduction relative to the estimated cost of biodiesel produced from soy oil.     

Antioxidant Effect of Nanoemulsions Based on Citrus Peel Essential Oils: Prevention of Lipid Oxidation in Trout

The antioxidant effects of oil‐in‐water nanoemulsion based on edible citrus peel essential oils on the fatty acid composition of rainbow trout fillets stored at 4 ± 2 °C are investigated. Fish fillets are treated with nanoemulsion and stored for 16 days. Lipid samples are converted into fatty acid methyl esters which are then detected by gas chromatagrophy (GC). The results show that palmitic acid (C16:0), palmitoleic acid (C16:1), stearic acid (C18:0), vaccenic acid (C18:1?‐7), oleic acid (C18:1?9), eicosenoic acid (C20:1?9), linoleic acid (C18:2?6), linolenic acid (C18:3?3), eicosapentaenoic acid (EPA) (C20:5?3), and docosahexaenoic acid (DHA) (C22:6?3) are the most important fatty acids in fish meat. While polyene index and hypocholesterolemic:hypercholesterolaemic fatty acid ratios decrease in trout fillets during cold storage, thrombogenicity index and atherogenicity index generally increase (especially in control and Tween 80 groups). The concentrations of monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) are higher in the treatment groups and the saturated fatty acids (SFAs) are lower in all groups compared to those of the control group. Application of nanoemulsion based on citrus essential oils prevents oxidation of PUFA especially EPA and DHA, thus has potential as a preservative for fish oil. Practical Applications: In recent years, nanotechnological applications have been increasingly applied to the protection of food. Similarly, natural essential oils are used to increase the shelf life of foods. This study demonstrates the combined effect of a new method of nanoemulsions and essential oils on the safety of foods.     

Lipidchemical Investigation of Some Oilplants for Edible Oil Production Cultivated in Mongolia

Seeds of some oilplants cultivated in Mongolia (rapeseed, sunflower, soya and mustard) were investigated for oil content and fatty acid composition in dependence of their varieties and cultivation regions. Seeds of given oilplant varieties have nearly same fatty acid composition, but they differ in their oil content. The rapeseed oils do not contain erucic acid, but the seed oil of mustard contained 15.5 % eicosenoic acid.     

Utilization of acid oils in making valuable fatty products by microbial lipase technology

Microbial lipase-catalyzed hydrolysis, esterification, and alcoholysis reactions were carried out on acid oils of commerce such as coconut, soybean, mustard, sunflower, and rice bran for the purpose of making fatty acids and various monohydric alcohol esters of fatty acids of the acid oils. Neutral glycerides of the acid oils were hydrolyzed byCanadida cylindracea lipase almost completely within 48 h. Acid oils were converted into fatty acid esters of short- and long-chain alcohols like C₄, C₈, C₁₀, C₁₂, C₁₆, and C₁₈ in high yields by simultaneous esterification and alcoholysis reactions withMucor miehei lipase as catalyst. Acid oils of commerce can be utilized as raw materials in making fatty acids and fatty acid esters using lipase-catalyzed methodologies.     

Determination of Origin of Commercial Flavored Rapeseed Oil by the Pattern of Volatile Compounds Obtained via GC–MS and Flash GC Electronic Nose

Flavored rapeseed oil (FRO) is a typical hot‐pressed oil and is widely consumed in China due to its strong characteristic flavor and intensive color. In this study, volatile profiles of 33 representative commercial rapeseed oils in China are characterized by gas chromatography‐mass spectrometry (GC‐MS) and flash gas chromatography (GC) electronic nose system. 51 volatile compounds are identified and the nitriles (methallyl cyanide and 5‐cyano‐1‐pentene), aldehydes (nonanal, 3‐furaldehyde, and 5‐methyl‐2‐furancarboxaldehyde), alcohols (1,5‐hexadien‐3‐ol, 2‐furanmethanol, and phenylethyl alcohol), and pyrazines (2,5‐dimethyl‐pyrazine and 2,6‐dimethyl‐pyrazine) are the major volatile compounds in FROs. Glucosinolate degradation products account for the highest proportion of these volatiles, which are found to have a positive correlation with the erucic acid content (R² = 0.796, p < 0.01). FRO from Sichuan province in the southwest of China can be characterized by the obvious distinctions in flash GC electronic nose combined with principal component analysis, which indicates that the flash GC electronic nose can be used as a promising method to identify the origins of FRO. Practical Applications: This work is helpful for expanding the knowledge of volatiles of commercial flavored rapeseed oil. The data can also serve as a basis for the quality assessment of hot‐pressed rapeseed oil. Meanwhile, the flash GC electronic nose combined with principal component analysis can be used as a promising method for the classification of flavor rapeseed oil production areas.     

Stable isotope characterization of olive oils. I—Compositional and carbon-13 profiles of fatty acids

Nearly 200 olive oils produced in the Mediterranean basin, mainly in Greece, during 4 yr from 1993 to 1996, were studied by gas chromatography (GC) and on-line GC-isotope ratio mass spectrometry (GC-C-IRMS). The composition of the oils in the more abundant fatty acids (C_16:0, C_16:1, C_18:0, C_18:1, C_18:2, and C_18:3) was obtained by GC after transesterification of the triglycerides into methyl esters. Using the hyphenated GC-C-IRMS technique, the ¹³C contents of the three most abundant acids, C_16:0, C_18:1, and C_18:2, were measured with satisfactory accuracy. The results, analyzed in terms of geographical, temporal, and botanical factors, provide new criteria for the authentication of olive oils.