Identification of Aromatic Fatty Acids in Butter Fat

Bovine milk fat contains a large variety of structurally different fatty acids. In this study, we describe the presence of aromatic fatty acids in a butter fat sample. Fatty acids were released from butter fat and converted into the corresponding methyl esters (FAME). Urea complexation was used to separate the main saturated fatty acids. GC/MS screening of the FAME in the filtrate of the urea complexation indicated the presence of aromatic fatty acids. By (1) conversion of two representatives into picolinyl esters which were analyzed by GC/MS, (2) linear log t_R over carbon number plots (R² = 0.95) and by the use of two reference standards we were able to show that the phenyl unit was located on the terminal carbon of the straight acyl chain of the FAME. In a fraction gathered by countercurrent chromatography we were able to identify 3‐phenylpropionic acid (Ph‐3:0), 4‐phenylbutyric acid (Ph‐4:0), 5‐phenylpentanoic acid (Ph‐5:0), 6‐phenylhexanoic acid (Ph‐6:0), 7‐phenylheptanoic acid (Ph‐7:0), 8‐phenyloctanoic acid (Ph‐8:0), 9‐phenylnonanoic acid (Ph‐9:0), 10‐phenyldecanoic acid (Ph‐10:0), 11‐phenylundecanoic acid (Ph‐11:0), 12‐phenyldodecanoic acid (Ph‐12:0), 13‐phenyltridecanoic acid (Ph‐13:0), along with one unsaturated phenyldecenoic acid (Ph‐10:1) isomer. Preliminary results indicate that the aromatic fatty acids may have been formed exogenously in the rumen of the cows. The total amount of the aromatic fatty acids was estimated at 0.15 mg/g butter fat, which corresponds with an average daily intake of ~5 mg per day in Germany and ~4.4 mg per day in Europe.     

Up to 21 Different Sulfur-Heterocyclic Fatty Acids in Rapeseed and Mustard Oil

Three sulfur-heterocyclic fatty acids (SHFA) had been tentatively identified in rapeseed oil in the late 1980s. In this study we aimed to enrich and verify the presence of potential SHFA in one sample of native rapeseed oil, refined rapeseed oil and mustard seed oil. Fifty-gram samples of the three oils were individually saponified and converted into methyl esters. The resulting samples were hydrogenated and subjected three times to urea complexation. The resulting extracts of native rapeseed oil and mustard oil contained 21 different SHFA with 18, 20, 22 or 24 carbons. The refined rapeseed oil contained only nine C₁₈-SHFA. Structure investigation of the SHFA was performed by gas chromatography with mass spectrometry (GC/MS) using methyl esters and also 3-pyridylcarbinol esters. A direct screening of non-enriched samples by GC/MS in the selected ion monitoring mode and by GC with flame photometric detector (sulfur-selective) verified that the SHFA were native compounds of the oils and no artefacts of the sample preparation. Similar abundances of the four isomer groups of SHFA with monoenoic fatty acids of the same carbon number in these and five further rapeseed and mustard samples indicated that these could be the precursors of the SHFA.     

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.     

Fatty Acids from a Glass Sponge <Emphasis Type="Italic">Aulosaccus</Emphasis> sp. Occurrence of New Cyclopropane-Containing and Methyl-Branched Acids

In order to identify new structures, the free fatty acids from an extract of a glass sponge Aulosaccus sp. (from the north‐west Pacific) belonging to one of the least chemically investigated classes (Hexactinellida), were fractionated by RP‐HPLC and analyzed by NMR spectroscopy and GC–MS of their pyrrolidine derivatives, methyl(ethyl) esters and their dimethyl disulfide adducts. One hundred and twenty‐three C₁₂–C₃₁ acids (including nine new compounds) were detected, one hundred and ten of these compounds have not been found previously in glass sponges. The levels of common methylene‐interrupted polyenes, monoenes of the (n–7) family and less common branched‐chain components proved to be high. New acids were shown to be 5,13‐dimethyl‐tetradec‐4‐enoic, cis‐10,11‐methylene‐heptadecanoic, 10,12‐dimethyl‐octadecanoic, cis‐12,13‐methylene‐nonadecanoic, (14E)‐13‐methyl‐eicos‐14‐enoic, 19‐methyl‐eicos‐13‐enoic, cis‐20,21‐methylene‐heptacosanoic, 27‐methyl‐octacos‐21‐enoic and (22Z)‐nonacos‐22‐enoic. Some important mass spectrometric characteristics of pyrrolidides of homologous cyclopropane fatty acids are reported and discussed.     

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).     

尿素包合法分离棕榈油甲酯化产物中C_(16)和C_(18)脂肪酸甲酯

采用尿素包合法分离棕榈油甲酯化物中不同碳链长度的脂肪酸甲酯,为农产品涂膜保鲜材料的开发提供原料。重点考察了尿素用量、溶剂用量、包合时间和包合温度对分离效果的影响,并以尿素用量、95%乙醇用量、包合温度为三因素,C16脂肪酸甲酯和C18脂肪酸甲酯的纯度为二指标,根据Box-Benhnken中心组合试验设计原理,利用Designexpert7.0.1软件分析优化了分离的工艺条件并建立了回归模型。优化的最佳工艺条件如下:在棕榈油甲酯化物用量为20g,尿素用量为35g,95%乙醇用量为120mL,包合温度为5℃,包合时间为16h的条件下,饱和脂肪酸甲酯相中C16脂肪酸甲酯的含量达78.5%,不饱和脂肪酸甲酯相中C18脂肪酸甲酯的含量达93.1%,分别比原料提高36.4%和40.8%。     

Heats of Combustion of Fatty Acids and Fatty Acid Esters

The military uses JP-8, a kerosene type hydrocarbon, to fuel most of its vehicles and is seeking a renewable alternative fuel that meets strict JP-8 specifications. Biodiesel is typically a mixture of different alkyl esters produced from the transesterification of triglycerides readily available in plant oils and used cooking oil. To date, no traditional biodiesel meets the requirements for heat of combustion, freezing point, viscosity and oxidative stability to be a stand-alone replacement for JP-8. This work is a fundamental survey of the heat of combustion of single fatty acid esters and a predictive model for estimating the heat of combustion given a known molecular structure. The gross heat of combustion of various C6–C18 fatty acids and the methyl, propyl and isopropyl esters of these fatty acids was measured. This study sought to relate the effect of chain length, degree of unsaturation and branching to the critical fuel property of the gross heat of combustion (H _c). It was found that H _c (kJ/g) increased with chain length. A nearly linear relationship was found between wt% carbon and hydrogen, and H _c. Group contribution models previously published for hydrocarbons and polymers were modified to more accurately predict the heat of combustion of the fatty acids and esters. Modification of the molar heat values of carboxylic acid, methyl, and methylene groups improved correlation of the model with the experimental results.     

<Emphasis Type="Italic">Trans</Emphasis>-Fatty Acid-Stimulated Mammary Gland Growth in Ovariectomized Mice is Fatty Acid Type and Isomer Specific

We previously reported that the trans-18:2 fatty acid trans-10, cis-12 conjugated linoleic acid (t10,c12-CLA) stimulates mammary gland development independent of estrogen and its receptor. Given the negative consequences of dietary trans-fatty acids on various aspects of human health, we sought to establish whether other trans-fatty acids could similarly induce ovary-independent mammary gland growth in mice. Prepubertal BALB/cJ mice were ovariectomized at 21 days of age then were fed diets enriched with cis-9, trans-11 CLA (c9,t11-CLA), or mixtures of trans-18:1 fatty acids supplied by partially hydrogenated sunflower, safflower, or linseed oil. The resultant mammary phenotype was evaluated 3 weeks later and compared to the growth response elicited by t10,c12-CLA, or the defined control diet. Whereas partially hydrogenated safflower oil increased mammary gland weight, none of the partially hydrogenated vegetable oils promoted mammary ductal growth. Similarly, the c9,t11-CLA supplemented diet was without effect on mammary development. Taken together, our data emphasize a unique effect of t10,c12-CLA in stimulating estrogen-independent mammary gland growth manifest as increased mammary ductal area and elongation that was not recapitulated by c9,t11-CLA or the partially hydrogenated vegetable oil diets.     

Effects of process parameters on EPA and DHA concentrate production from Atlantic salmon by-product oil: Optimization and characterization

Supercritical carbon dioxide (SC-CO₂) extracted Atlantic salmon frame bone oil (SFBO) was used for Eicosapentaenoic acid and Docosahexaenoic acid (EPA-DHA) concentrate production by urea complexation. Urea/fatty acids (2.5 to 4.0 w/w), crystallization temperature (?24 to ?8 °C) and crystallization time (8 to 24 h) were studied by Box-Behnken Design (BBD) to maximize EPA-DHA content. Highest EPA-DHA content was 60.63% at urea/fatty acids 4.0 w/w, crystallization temperature ?15.67 °C and crystallization time 8 h. EPA-DHA concentrate showed improvement of EPA-DHA from 6.39% in SFBO to 62.34%, increase of astaxanthin content from 21.33 μg/g in SFBO to 44.69 μg/g in EPA-DHA concentrate, no residual urea and reduction of many off-flavor compounds. The EPA-DHA yield showed an inverse relation with the urea/fatty acids, whereas its concentration increased proportionally with urea/fatty acids. Therefore, EPA-DHA concentrate produced from SFBO by urea complexation may be an efficient technique to provide ω-3 polyunsaturated fatty acids to the consumers.     

Enzymatic pretreatment of deodorizer distillate for concentration of sterols and tocopherols

Separation of sterols and tocopherols from fatty acids in deodorizer distillate was facilitated through lipase-catalyzed modification of fatty acids in canola, mixed and soya deodorizer distillates. The fatty acid esterification with methanol catalyzed by SP-382 (an immobilized nonspecific lipase) proceeded rapidly, with conversion of fatty acid to methyl ester in 5 h being 96.5, 83.5 and 89.4%, respectively. A model mixture of pure oleic acid and dl-α-tocopherol was used to study any potential side reactions that may lower the tocopherol content during the esterification reaction. Under the conditions employed, the loss of tocopherol was less than 5%. Simple vacuum distillation (1–2 mm Hg) was employed to remove the volatile fraction (methyl esters of fatty acids, some fatty acids and other volatiles) of the esterified deodorizer distillate, leaving behind sterols, sterol esters and tocopherols. Sterols and tocopherols were almost completely retained in the residue fraction with recoveries in the range of 95%. Overall recoveries of sterols and tocopherols after esterification and distillation were over 90% for all the deodorizer distillate samples.     

Identification of conjugated fatty acids by gas chromatography-mass spectrometry of 4-methyl-1,2,4-triazoline-3,5-dione adducts

4-Methyl-1,2,4-triazoline-3,5-dione was reacted with conjugated fatty acid methyl esters to form Diels-Alder cycloaddition products. The electron impact mass spectra of conjugated octadecadienoates and 9,11,13-octadecatrienoate were simple and informative and allowed the positions of the double bonds to be determined. The dienes gave single adducts whereas the triene formed four products that corresponded to two stereoisomers of the adducts of the 9,11-diene system and two of the 11,13-diene system. The method can be used to complement other methods for identifying conjugated fatty acids.     

GC-MS characterization (Chemical lonization and electron impact modes) of the methyl esters and oxazoline derivatives of cyclopropenoid fatty acids 1

The CI-(CH₄) mass spectra of the methyl esters and the EI mass spectra of the oxazoline derivatives of three cyclopropenoid fatty acids (malvalic, sterculic and α- hydroxy-sterculic acid) from the seed oil ofPachira aquatica were found to be useful for structure elucidation of such compounds. Furthermore, some hitherto unknown minor fatty acids were identified and the nuclear magnetic resonance data of the oil and α-hydroxysterculic acid methyl ester are presented.     

Preparation of heptadecenoic acid fromCandida tropicallis yeast

In this paper a method is described for preparing 10 g or more of heptadecenoic acid (C17:1ω8) of 99 p.100 purity fromCandida tripicallis yeast. Three cycles of treatment, based on crystallization techniques, were used successively: (1) Crystallization of fatty acids (in free form) from acetone at −25 C induced the elimination of most of the saturated fatty acids, and at −60 C, of all of the poly-unsaturated acids. (2) Inclusion formation of fatty acids (as methyl esters) with urea at hC induced the removal of all of the remaining saturated methyl esters and most of methyl oleate. (3) Crystallization of fatty acid methyl esters from acetone at −60 C removed almost all the remaining monounsaturated methyl esters (methyl palmitoleate and methyl oleate). Total efficiency of the preparation was about 17 p. 100.     

Determination of low level trans unsaturation in physically refined vegetable oils by capillary GLC — Results of 3 intercomparison studies

The analytical performance of capillary gas‐liquid chromatographic (GLC) methods for the quantitative determination of trans fatty acids (TFA) in physically refined rapeseed and soybean oils was evaluated by 3 intercomparison studies. The participants were allowed to use their own methodology regarding derivatization and GLC conditions and were not requested to follow a fixed method protocol. However, certain requirements relating to the separation efficiency (chromatographic separation of critical pairs) and the accuracy (validation of the response factors using a certified reference material) of the method(s) applied, had to be fulfilled. All 12 participating laboratories employed fused silica capillary columns coated with cyanopropyl polysiloxane for the separation of fatty acid methyl esters. Analytical precision was sufficient (relative standard deviation for reproducibility 13%) for the quantification of trans isomers occurring at levels >0.1 g/100 g in physically refined vegetable oils, i.e. trans isomers of linolenic acid. For TFA levels <0.1 g/100 g (trans isomers of oleic and linoleic acid) precision dropped sharply (relative standard deviation for reproducibility >30%).     

Detection of trace fatty acids in fats and oils by urea fractionation and gas-liquid chromatography

The detection of trace fatty acids (<0.1%) in a fat or oil by gas-liquid chromatography is possible when the methyl esters are fractionated with urea to provide a number of less complex fractions. Identification and estimation of trace fatty acids is simplified by quantitative removal of other fatty acids having similar gas chromatographic retention times. A detailed knowledge of the order in which inclusion compounds are formed was obtained by fractionating a complex mixture of marine and vegetable fatty acids. In addition, lanolin was fractionated to determine the preferential order in which saturated, branched chain (iso-, anteiso-) and hydroxy acids form inclusion compounds. Using urea fractionation and gas chromatography, 52 trace fatty acids were tentatively identified in butter, 30 in lard, and 26 in walnut oil. Presented at the AOCS Meeting in New Orleans, 1964.     

Stability of cyclopropane and conjugated linoleic acids during fatty acid quantification in lactic acid bacteria

Seven methods commonly used for fatty acid analysis of microgrganisms and foods were compared to establish the best for the analysis of lyophilized lactic acid bacteria. One of these methods involves fat extraction followed by methylation of fatty acids, while the other methods use a direct methylation of the samples, under different operating conditions (e.g., reaction temperature and time, reagents, and pH). Fatty acid methyl esters were identified by gas chromatography-mass spectrometry and quantified by on-column capillary gas chromatography. Two reliable methods for the analysis of fatty acids in bacteria were selected and further improved. They guarantee high recovery of classes of fragile fatty acids, such as cyclopropane and conjugated acids, and a high degree of methylation for all types of fatty acid esters. These two direct methylation methods have already been successfully applied to the analysis of fatty acids in foods. They represent a rapid and highly reliable alternative to classical time-and solvent-consuming methods and they give the fatty acid profile and the amount of each fatty acid. Using these methods, conjugated linoleic acids were identified and quantified in lactic acid bacteria.     

脲包法分离不饱和脂肪酸甲酯的研究

以混合脂肪酸甲酯为原料,采用尿素包合法（脲包法）分离不饱和脂肪酸甲酯。通过正交试验,得到了最佳工艺条件：混合脂肪酸甲酯（w）：尿素（w）：甲醇（v）为1：2．09：8．36,包合温度-10℃,包合时间18h。经过一次包合,不饱和脂肪酸甲酯的含量由原来的47．69％提高到86．74％,收率54．19％。     

Analysis of Intact Cholesteryl Esters of Furan Fatty Acids in Cod Liver

Furan fatty acids (F‐acids) are a class of natural antioxidants with a furan moiety in the acyl chain. These minor fatty acids have been reported to occur with high proportions in the cholesteryl ester fraction of fish livers. Here we present a method for the direct analysis of intact cholesteryl esters with F‐acids and other fatty acids in cod liver lipids. For this purpose, the cholesteryl ester fraction was isolated by solid phase extraction (SPE) and subsequently analyzed by gas chromatography with mass spectrometry (GC/MS) using a cool‐on‐column inlet. Pentadecanoic acid esterified with cholesterol was used as an internal standard. GC/MS spectra of F‐acid cholesteryl esters featured the molecular ion along with characteristic fragment ions for both the cholesterol and the F‐acid moiety. All investigated cod liver samples (n = 8) showed cholesteryl esters of F‐acids and, to a lower degree, of conventional fatty acids. By means of GC/MS‐SIM up to ten F‐acid cholesteryl esters could be determined in the samples. The concentrations of cholesteryl esters with conventional fatty acids amounted to 78–140 mg/100 g lipids (mean 97 mg/100 g lipids), while F‐acid cholesteryl esters were present at 47–270 mg/100 g lipids (mean 130 mg/100 g lipids).     

Enrichment of Omega-3 Fatty Acids of Refined Hoki Oil

Enrichment of the omega-3 (n-3) fatty acids of refined hoki oil (RHO) intact triglycerides (TG) and via free fatty acids (FFA), was carried out in the present study using established methods of dry fractionation (DF), low temperature solvent crystallization (LTSC) and urea complexation (UC) and positional distribution of fatty acids in the intact TG was determined by Nuclear Magnetic Resonance (NMR) analysis. Results showed that n-3 fatty acids were enriched in liquid fractions of all methods except DF, where the highest concentration was obtained via the UC method (83.00 %). The FFA form of the oil produced a higher concentration (40.81 %) of n-3 fatty acids via the LTSC method compared to the TG form (31.50 %). The percentages of the total saturated fatty acid (SFA) in the liquid fractions in all methods were lower, ranging from 1.60 % (UC) to 21.44 % (DF) compared to the RHO parent oil (24.05 %). The percentages of total monounsaturated fatty acids (MUFA) in the liquid fractions were similar to the solid fractions except for the UC method where total MUFA was six times higher in the solid fraction. In LTSC-FFA and UC methods, the enrichment factor for EPA was lower, ranging from 1.61 (LTSC-FFA) to 2.83 (UC), than DHA which ranged from 1.64 (LTSC-FFA) to 3.88 (UC). EPA was preferentially located at the sn-1,3 position and DHA was significantly located at the sn-2 position which is the favoured location for intestinal digestion.     

Preparation of malvalic and sterculic acid methyl esters from Bombax munguba and Sterculia foetida seed oils

A method has been developed for the preparation of highly pure malvalic (cis-8,9-methyleneheptadec-8-enoic) and sterculic (cis-9,10-methyleneoctadec-9-enoic) acid methyl esters starting from Bombax munguba and Sterculia foetida seed oils. The methyl esters of these oils were prepared by sodium methylate-catalyzed transmethylation followed by cooling (6°C) the hexane solution of crude methyl esters and separation of insoluble fatty acid methyl esters by centrifugation in the case of B. munguba and by column chromatography in the case of S. foetida. Subsequently, the saturated straight-chain fatty acid methyl esters were almost quantitatively removed by urea adduct formation. Finally, methyl malvalate and methyl sterculate were separated from the remaining unsaturated fatty acid methyl esters, in particular methyl oleate and methyl linoleate, by preparative high-performance liquid chromatography on C₁₈ reversed-phase using acetonitrile isocratically. Methyl malvalate and methyl sterculate were obtained with purities of 95–97 and 95–98%, respectively.