In Vitro and In Vivo Digestibility of Soybean,Fish, and Microalgal Oils,and Their Influences on Fatty Acid Distribution in Tissue Lipid of Mice

The digestion rates of microalgal (docosahexaenoic acid, DHA, 56.8%; palmitic acid, 22.4%), fish (DHA, 10.8%; eicosapentaenoic acid, EPA, 16.2%), and soybean oils (oleic, 21.7%; linoleic acid, 54.6%) were compared by coupling the in vitro multi-step and in vivo apparent digestion models using mice. The in vitro digestion rate estimated based on the released free fatty acids content was remarkably higher in soybean and fish oils than in microalgal oil in 30 min; however, microalgal and fish oils had similar digestion rates at longer digestion. The in vivo digestibility of microalgal oil (91.49%) was lower than those of soybean (96.50%) and fish oils (96.99%). Among the constituent fatty acids of the diet oils, docosapentaenoic acid (DPA) exhibited the highest digestibility, followed by EPA, DHA, palmitoleic, oleic, palmitic, and stearic acid, demonstrating increased digestibility with reduced chain length and increased unsaturation degree of fatty acid. The diet oils affected the deposition of fatty acids in mouse tissues, and DHA concentrations were high in epididymal fat, liver, and brain of mice fed microalgal oil. In the present study, microalgal oil showed lower in vitro and in vivo digestibility, despite adequate DHA incorporation into major mouse organs, such as the brain and liver.     

深海鱼油中脂肪酸的分析

用氢氧化四甲胺／甲醇酯化法使深海鱼油内的三酸甘油酯中的脂肪酸和游离脂肪酸转化成脂肪酸甲酯,用气相色谱和气相色谱／质谱进行分析,鉴定出４１个组分,并对其中的主要组分顺式－５,８,１１,１４,１７－十二碳五稀酸（ＥＰＡ）和顺式－４,７,１０,１３,１６,１９－二十二碳六烯酸（ＤＨＡ）建立了定量分析方法。方法的相对标准偏差分别为４．３％（ＥＰＡ）和４．７％（ＤＨＡ）。ＥＰＡ和ＤＨＡ的回收率分别为１００．     

Quantitative Determination of Isostearic Acid Isomers in Skin Creams by GC-MS-SIM

“Isostearic acid” is frequently listed as an ingredient of skin creams and other cosmetics. In the four skin creams analyzed, “isostearic acid” was esterified with isopropanol, as well as sorbitan or polyglycerols. “Isopropyl isostearate” was isolated by HCl treatment and saponification whereas emulsifiers (sorbitan or polyglycerol isostearates) were enriched by means of a C₁₈-cartridge. Fatty acids in the resulting lipid fraction were transferred into methyl esters. 25:0 and 19:0 methyl esters were used as internal standards. GC-EI-MS was used to determine that “isostearic acid” was a mixture of many methyl-branched isomers of stearic acid (18:0) in all four skin creams. Thus, it may be better termed “isostearic acids”. The branched-chain nature of isostearates was verified by formation and analysis of picolinyl esters of skin cream fatty acids by GC-EI-MS. Twenty-five 18:0 isomers were detected and the main products had one methyl branch on carbons C₁₀–C₁₄. Two late eluting isostearic acid isomers were identified as 16-methyl heptadecanoic acid (i18:0) and 15-methyl heptadecanoic acid (a18:0). GC-EI-MS in the selected ion monitoring (SIM) mode with m/z 87 as quantification ion was used for the determination of i18:0 methyl ester. The quantities of i18:0 in the samples amounted to 10–20 mg g^?1 skin cream. The contribution of i18:0 to the sum of all 18:0 isomers in the four skin cream samples was 8.5 ± 1.1%. Instead of determining all individual isostearates in a product, we suggest the quantitative determination of i18:0 followed by multiplication with factor 11.75 (~reciprocal value of 8.5%, see above) as a simple method for the quantification of isostearates in cosmetics.     

Characterization and purification of polyunsaturated fatty acids from microalgae by gas chromatography-mass spectrometry and countercurrent chromatography

Summary The present study was undertaken in order to characterize then to purify fatty acids from marine phytoplankton. From a crude mixture of fatty acid methyl esters it was possible to isolate by countercurrent chromatography a mixture of four polyunsaturated fatty acid methyl ester identified as being hexadecatrienoic acid methyl ester, octadecatetraenoic acid methyl ester, eicosapentaenoic acid methyl ester and docosahexaenoic acid methyl ester by gas chromatography coupled with mass spectrometry in electron impact and in positive-ion chemical ionization mode. The four polyunsaturated fatty acids are in different ratios in mixtures from the two microorganisms:Skeletonema costatum andIsochrysis galbana.     

Isolation of 6,9,12,15-Hexadecatetraenoic Fatty Acid (16:4n-1) Methyl Ester from Transesterified Fish Oil by HSCCC

Fish oil is considered a healthy food due to the presence of large amounts of polyunsaturated fatty acids (PUFAs), especially in the form of n-3 fatty acids 5,8,11,14,17-eicosapentaenoic acid (20:5n-3; EPA) and 4,7,10,13,16,19-docosahexaenoic acid (22:6n-3; DHA). However, fish oil is known to contain many other PUFAs, some of which are uncommon and whose bioactivity is scarcely investigated. In this study, we isolated the rare PUFA 6,9,12,15-hexadecatetraenoic fatty acid (16:4n-1) which bears a double bond on the terminal carbon from fish oil in form of its methyl ester. We used high-speed counter-current chromatography (HSCCC) for the fractionation of 500 mg-portions of fatty acid methyl esters prepared from a fish oil capsule and investigated the fractions by GC/MS. Twenty-eight 13-mL fractions were collected and fatty acid methyl esters were detected in fractions 11–23. The elution was carried out in normal phase mode, providing the long-chained saturated and monoenoic fatty acids first. More than 100 fatty acids ranging from 10:0 to 26:0 could be identified in the HSCCC fractions, and most of them were polyunsaturated. The reproducibility of the HSCCC method was shown by repeated injection of the fish oil and the fractions containing 6,9,12,15-hexadecatetraenoic fatty acid (16:4n-1). The late eluting 16:4n-1 methyl ester was isolated in pure form and its structure was verified.

     

An infrared spectroscopic method for quantitative analysis of fatty alcohols and fatty acid esters in machinery oils

A new infrared spectroscopic method suitable for determining total fatty alcohol and fatty acid ester concentrations in industrial oils has been developed. Oil samples were diluted with toluene (1:3 w/w), the toxicity and volatility of which are relatively low compared with more commonly used IR solvents, like carbon tetrachloride or carbon disulfide. Mixture standards were prepared from dodecanol, tetradecanol, octadecanol, methyl stearate and methyl palmitate. Some analytical and statistical tests were performed on the developed method. The recoveries and the repeatability of the method proved to be sufficient for the quantitative determination of fatty alcohol and fatty acid ester additives in industrial oils. Reproducibility testing in another laboratory also produced satisfactory results. The developed method also proved to be relatively quick and simple. This method was developed to satisfy industry’s need to determine the concentrations of these oil additives, and it has already been applied successfully in machinery oil analysis.     

Response Factor Correction for Estimation of Ester Content in Biodiesel

EN 14103 is generally used for quantification of ester content in biodiesel free of heptadecanoate ester (C17:0) or methyl nonadecanoate (C19:0), which are employed as internal standards. It was observed that ester content obtained by EN 14103 method did not match with theoretical value of biodiesel, as the method did not take care of response factors of each component to compensate for changes in detector sensitivities. In this study, the whole range of fatty acid (C₆–C_24:1) methyl esters have been taken into consideration for the calculation of the ester content. Methyl nonadecanoate (C19:0) was used as an internal standard. The response factors of both the saturated and unsaturated methyl esters in the range C₆–C_24:1 were estimated and found in the range 0.97–1.16. The ester content was calculated after applying the response factors of each methyl ester. The results obtained by this method agreed well with the theoretical value as compared to estimated value using EN14103 method. The results obtained from this method also show good correlation (R ² = 0.98) with ¹H-NMR method. Further, this method does not depend on nature of biodiesel feed stock and is applicable to all methyl biodiesel samples obtained from different raw materials.     

Determination of lipids in infant formula powder by direct extraction methylation of lipids and fatty acid methyl esters (FAME) analysis by gas chromatography.

Fatty acid methyl esters (FAMEs) of pure triglyceride standards, oils, and fat from dry matrixes were formed by transesterification using sodium methoxide in methanol-hexane. FAMEs were produced by direct addition of sodium methoxide-hexane to samples and heating to simultaneously extract and transesterify acyl lipids. FAMEs were quantitated by capillary gas chromatography (GC) over a fatty acid concentration range of 0 to 1.7 mg/mL (r > or = 0.9997). Total fat was calculated as the sum of individual fatty acids expressed as triglyceride equivalents, in accordance with nutrition labeling guidelines. Saturated, polyunsaturated, and monounsaturated fats were calculated as sums of individual free fatty acids. Absolute recoveries determined from individual fatty acids in test samples ranged from 69.7 to 106%. Recoveries (relative to the C13:0 internal standard) for individual fatty acids in test samples ranged from 95 to 106%. Reproducibility was constant at each fatty acid level in the reaction mixture (n = 5, coefficient of variation [CV] < 2%). Absolute recovery determined from the sum of total fatty acids in standard reference material (SRM) 1846 (powdered infant formula) was 96.4%. Analysis of SRM 1846 gave results that agreed closely with the certified fat and fatty acid values. Analysis of commercial infant formula gave results that were comparable to those obtained with AOAC Method 996.01. The direct extraction methylation procedure is rapid, and the transesterification of acyl lipids to form FAMEs is complete within 15 min. Classical saponification and refluxing are not required. This method provides FAMEs free of interferences and easily quantitated by GC or confirmed by GC/mass spectrometry (MS). Unambiguous MS identification of individual FAMEs derived from pure standards, SRM 1846, and powdered infant formula product was obtained.     

Study of the GC-MS determination of the palmitic-stearic acid ratio for the characterisation of drying oil in painting: La Encarnación by Alonso Cano as a case study

The correct identification of drying oils plays an essential role in providing an understanding of the conservation and deterioration of artistic materials in works of art. To this end, this work proposes the use of peak area ratios from fatty acids after ensuring that the linear responses of the detector are tested. A GC-MS method, previously reported in the literature, was revisited to its developed and validated in order to identify and quantify of eight fatty acids that are widely used as markers for drying oils in paintings, namely myristic acid (C(14:0)), palmitic acid (C(16:0)), stearic acid (C(18:0)), oleic acid (C(18:1)), linoleic acid (C(18:2)), suberic acid (2C(8)), azelaic acid, (2C(9)) and sebacic acid (2C(10)). The quaternary ammonium reagent m-(trifluoromethyl)phenyltrimethylammonium hydroxide (TMTFAH) was used for derivatization prior to GC-MS analysis of the oils. MS spectra were obtained for each methyl ester derivative of the fatty acids and the characteristic fragments were identified. The method was validated in terms of calibration functions, detection and quantification limits and reproducibility using the signal recorded in SIR mode, since two of the methyl derivatives were not totally separated in the chromatographic run. The proposed method was successfully applied to identify and characterise the most widely used drying oils (linseed oil, poppy seed oil and walnut oil) in the painting La Encarnación. This 17th century easel painting is located in the main chapel of the cathedral in Granada (Spain) and was painted by the well-known artist of the Spanish Golden Age, Alonso Cano (1601-1667).     

Investigation of Fatty Acid Composition of Ammi majus Seed Oil by Gas Chromatography Mass Spectrometry

The Ammi majus seeds oil constituents of methyl ester derivatives of fatty acids were analyzed using Gas Chromatography coupled to mass spectrometer. The results obtained containing the saturated as well as unsaturated fatty acids of majus seeds oils. A total of 18 different components were identified and quantified. Methyl ester of linoleic acid was found in high concentration 9.00%, among the identified analytes of interest. In addition methyl ester of Oleic acid 5.60%, Palmitic acid 3.98% Linolenic acids 1.42% were found. Concentration of the rest of identified fatty acids analytes were less than 1%. Thus from the results it is apparent that due to the presence of high percentage of valuable analytes concentrations detected in the fatty acid of A. majus, has increased its importance for the consumption in the pharmaceuticals as well as its applications in the new formulations for various skin diseases to prevent and cure from different infections.     

Quantification of eicosapentaenoic and docosahexaenoic acid geometrical isomers formed during fish oil deodorization by gas-liquid chromatography

Long-chain polyunsaturated fatty acids (LC-PUFAs) of the n-3 series and especially eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively) have important biological properties. The main dietary sources of LC-PUFAs are fish and fish oil. Geometrical isomerization is one of the main reactions happening during the thermal treatment of polyunsaturated fatty acids. Refined fish oils are used to supplement food products in LC-PUFAs and the quality of these nutritional ingredients have to be controlled. In the present study, a suitable method for the quantification of EPA and DHA geometrical isomers in fish oils by gas-liquid chromatography (GC) is presented. A highly polar capillary column (CP-Sil 88, 100 m) operating under optimal conditions was used. Method selectivity was studied by GC-mass spectrometry. The performance characteristics of the quantification method were studied using samples of fish oil deodorized at 220 degrees C for 3 h. The linearity of the method was assessed by analyzing composite samples obtained by mixing fish oil deodorized at 220 degrees C with semi-refined fish oil (control). Precision was evaluated by analyzing the same samples in triplicate. Results showed that the validated method is suitable to quantify low amounts of geometrical (trans) isomers of EPA and DHA in refined fish oils. The limits of quantification of the EPA and DHA geometrical isomers are 0.16 and 0.56 g/100 g of fish oil, for EPA and DHA, respectively. Commercially available LC-PUFA oil samples were evaluated by using the validated method. The results show that the oils analyzed contain low amounts (<1% of total fatty acids) of geometrical isomers of EPA and DHA.     

羟肟酸法快速测定食用油主要营养必需脂肪酸

建立了用ＨＰＬＣ简便快速测定食用油主要营养必需脂肪酸的羟肟酸法。样品一步衍生成羟肟酸上机分析,不需分离纯化。线性范围为０．０５～０．６０ｇ／Ｌ,回收率９６．９３％,ＲＳＤ＝１．８０％（ｎ＝４）,日内和日间ＲＳＤ分别为１．２４％和１．６２％（ｎ＝６）。比较１８∶３,１８∶２和１８∶１的甲酯与相应的三脂肪酸甘油酯标准品衍生的标准曲线,发现二者转化率均相差近一倍,回收率实验和样品实测结果亦证实,选取甲酯标准品衍生作标准曲线用于油脂定量是不合理的。     

Prediction of the acid value,peroxide value and the percentage of some fatty acids in edible oils during long heating time by chemometrics analysis of FTIR-ATR spectra

Edible oils are used in the preparation of foods as a part of their recipe or for frying. So to ensure of food safety, checking the quality of the oils before and after usage is an important subject in food control laboratories. In this study, edible oils from four different sources (canola, corn, sunflower and frying) were heated for 36 h at 170 °C and sampling was done every 6 h. The free fatty acid, peroxide value and the content of some fatty acids (C16:0, C18:0, C18:1, C18:2, C18:3) of the oil samples were determined by standard methods. Then, the ATR-FTIR spectra of the samples were collected. The partial least squares (PLS) regression combined with genetic algorithm was performed on the spectroscopic data to obtain the appropriate predictive models for the simultaneous estimation of acid value, peroxide value and the percentage of five kinds of fatty acids. The effect of some preprocessing methods on these models was also investigated. Preprocessing of data by orthogonal signal correction (OSC) resulted in the best predictive models for all oil properties. The correlation coefficients of calibration set (>0.99) and validation set (>0.86 and in most case >0.94) of the OSC–PLS model suggested suitable predictive modeling for all studied parameters in the oil samples. This method could be suggested as a rapid, economical and environmental friendly technique for simultaneous determination of seven noted parameters in the edible oils.     

Optimization of the selectivity of a cyanopropyl stationary phase for the gas chromatographic analysis of trans fatty acids

The quantification of monounsaturated and polyunsaturated trans fatty acids in partially hydrogenated fats by gas-liquid chromatography on a CP-Select CB-FAME capillary column was optimized using equivalent chain length values of fatty acids methyl esters that could coelute in the temperature range from 155 to 200 degrees C. The most appropriate temperature for the simultaneous determination of these trans isomers is around 197 degrees C. It is proposed a system to discriminate trans from cis octadecenoic fatty acid methyl esters based on the angular coefficient values of the equivalent chain length curves. The limits of detection and quantification were 0.28 and 0.93 mg g(-1). Quantification was performed in the range from 0.93 to 280 mg g(-1). Quantification accuracy was estimated by spike recovery of elaidic and trans-13-octadecenoic acids in hydrogenated fat samples. The obtained levels were from 97.60 to 103.28% for elaidic acid and from 98.12 to 99.27% for trans-13-octadecenoic acid. These results indicate that the accuracy of the methodology proposed for the quantification of monounsaturated and polyunsaturated trans fatty acids in hydrogenated fats is adequate.     

脂肪酸的色谱保留时间规律与质谱特征研究及其在食品分析中的应用

用石油醚提取食品中的脂肪,经甲酯化反应后,采用HP-88(100m×0.25mm,0.33μm)弹性石英毛细管柱分离脂肪酸甲酯的同系物及异构体,GC/MS法测定。研究了不同链长脂肪酸的同系物及异构体的气相色谱出峰顺序,得到其保留时间规律;研究了不同脂肪酸的质谱断裂规律,选择3个特征离子来鉴定脂肪酸成分。建立了3个特征离子确定脂肪酸碳数及双键数目,色谱保留时间规律确定脂肪酸顺反异构体及双键位置异构体的方法。本法无需标准品即可快速测定脂肪酸同系物及异构体的含量,适用于脂肪酸组成的研究;及油脂、食品中脂肪酸,特别是反式脂肪酸的测定。     

Analysis of thermal,oxidative and cold flow properties of methyl and ethyl esters prepared from soybean and mustard oils

Oilseed crop with high oil content and promising ecological adaptability are potential sources for competitive biodiesel production. This study investigates the scope of utilizing biodiesel development through the methyl and ethyl ester from soybean and mustard oil as an alternative fuel. Methyl and ethyl esters of oils having different fatty acids compositions such as soybean (SOME and SOEE) and mustard oil (MUME and MUEE) were prepared by transesterification with methanol and ethanol in the presence of an alkali-KOH catalyst. The gas chromatographic (GC) analysis of oil samples revealed that primary fatty acid composition in soybean oil was linoleic acid (C_18:2, 51.93%), followed by oleic acid (C_18:1, 22.82%), palmitic acid (C_16:0, 11.56%), linolenic acid (C_18:3, 5.95%) and stearic acid (C_18:0, 4.32%). Whereas, the main components in mustard oil were erucic acid (C_22:1, 32.81%), oleic acid (C_18:1, 24.98%), eicosenoic acid (C_20:1, 10.44%), linolenic acid (C_18:3, 8.61%) and palmitic acid (C_16:0, 2.80%). The physicochemical properties (acid value, iodine value, calorific value, flash point, pour point etc.) of methyl and ethyl ester samples were estimated and found to be within the acceptable range of ASTM D6751 standards specifications. The prepared esters and oil samples were examined for cold flow properties by differential scanning calorimetry (DSC). Results revealed better cold flow properties for MUME (−2.55 °C) and MUEE (−3.10 °C) than SOME (3.21 °C) and SOEE (1.83 °C) due to more unsaturated fatty acid content in MU. Thermal and oxidative stability of samples was determined by thermogravimetric analysis (TG) and differential thermal analysis (DTA). The thermal and oxidative stability ranking of the samples was in the order of oil > methyl esters > ethyl esters.

     

The Petroleum Industry Surfactants Synthesized from Fish Oils

Biodegradable surfactants for the petroleum industry have been synthesized by the sulfurization of fish oils. A qualitative composition analysis of surfactants was conducted by FTIR spectroscopy that showed the presence of sulfonic acid groups in the samples. Previously, several samples of the technical fish oils (fish processing waste) have been studied with regard to their use for the synthesis of biodegradable surfactants. It has been shown by gas–liquid chromatography, FTIR spectroscopy, high-performance liquid chromatography, and mass spectrometry method that samples under study contain a large amount of saturated and nonsaturated fatty acids with hydrocarbon radicals comprising from 16 to 22 carbon atoms. The results reveal that the concentration of oleic acid approaches to 15 wt%. Fish oils with a high content of free fatty acids were used as the basis for the synthesis of technical, environmentally friendly surfactants that can be applied in the petroleum industry.     

Improved method of determination of biologically important C10:0-C22:6 fatty acids as their 2-nitrophenylhydrazides by reversed-phase high-performance liquid chromatography

Fatty acids were separated by reversed-phase high-performance liquid chromatography after derivatization with 2-nitrophenylhydrazine hydrochloride in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. The separation of a mixture of fourteen kinds of biologically important fatty acid hydrazides (C10:0-C22:6) was achieved within 15 min. Using margaric acid (C17:0) as internal standard, each fatty acid could be quantitated over the range of 2.5-5000 pmol per injection. Analytical recoveries ranged from 98.1 to 102.6%. The intra- and inter-assay coefficients of variation were less than 2.5 and 3.2%, respectively. For the determination of esterified fatty acids in fats and oils, the saponified mixture was directly derivatized without extraction. This method was compared gave similar fatty acid profiles to those obtained with the conventional liquid-liquid extraction method. It is simple, rapid and accurate for routine analyses of esterified fatty acids in biological materials.     

Separation of fatty acids or methyl esters including positional and geometric isomers by alumina argentation thin-layer chromatography

This paper describes novel and rapid thin-layer chromatography procedures for the analysis of fatty acids and methyl esters using silver-impregnated alumina sheets. These techniques are known in most laboratories, and the equipment is readily available. The fatty acid method allows a separation of petroselinic (C18:1 delta 6c), oleic (C18:1 delta 9c), elaidic (C18:1 delta 9t), erucic (C22:1 delta 13c), and brassidic acids (C22:1 delta 13t), and the methyl ester method gives an excellent resolution with respect to the number, configuration, and position of the unsaturated centers. Sufficient separation for the subsequent ozonolysis and chromatographic quantification of isomeric C18 and C22 fatty acid methyl esters is obtained with both methods.     

An automated transesterification technique for quantitation of acid precursors of ester-based oils

A novel automated transesterification (ATE) technique has been developed for the quantitative determination of acid components used in synthesizing ester-based oils. The ATE technique has been successfully tested over a period of more than five years using several commercially available ester-based new and used refrigeration oils and jet oils. In this automated technique, the ester-based oil is transesterified using a commercially available SAP-Ester kit, and the resulting methyl ester mixture is then extracted and analyzed by gas chromatography (GC). During the transesterification, the large number (50-100) of oil-ester components are significantly reduced to a much smaller group of easily resolvable and quantitatable methyl esters (mostly < 6, depending upon the number of acids used).