The Saturated sn-2-Triglycerides of Palm-Kernel Oil

The saturated sn-2-triglycerides (the fatty acid esterified at the 2-position is known) of palm-kernel oil, representing 78%, was isolated by argentation thin-layer chromatography. The nine groups of this fraction (triglycerides with the same total acyl carbon atoms) were fractionated by gas-liquid chromatography and their component fatty acids determined. From the fatty acid composition of each group it was possible to determine mathematically the component triglyceride types of the group (the 3 fatty acids are known, but their positional distribution is not). The proportion of 46 types were calculated in this way. The major fractionate groups (6 out of 9) were hydrolyzed by pancreatic lipase. From the component 2-mono-glycerides it was possible to determine the proportion of 44 sn-2-triglycerides which account for 75% of the oil triglycerides. Trilaurin (21%) is the major component, followed by sn-2-lauro-1,3-lauromyristin (12%). These two triglycerides together form one third of the glyceride content of the oil. Sn-2-lauro-1,3-caprylolaurin (7%), 5 sn-2-triglycerides (2 to 5%), 9 (1 to 2%) were also found, and 27 triglycerides present at less than 1%. The calculated 1,3-random-2-random distribution of fatty acids on glycerol molecules exhibited great differences from the experimentally determined distribution. Consequently, calculations of this kind cannot replace a complete analytical analysis of palm-kernel oil such as the one reported in this work.     

Triglyceride composition of coconut oil

Triglycerides of coconut oil were fractionated by GLC into 13 groups based on their carbon numbers of 28 to 52. These groups represent 99.8% of the total glycerides of coconut oil. With the fatty acid composition of each group, it was possible to calculate the composition of 79 types of triglycerides. These types are defined by the nature of their constitutive fatty acids but the position of the acids on glycerol is unknown. Each group usually has only one major type of triglyceride. For example, group 36 has 52% of trilaurin. Also four types of triglycerides comprise 42.4% of the total glycerides and 24 types comprise 85%. The experimentally found distributions in each group are compared to the random distributions calculated from the fatty acid composition. For groups with carbon numbers 38 and 40, the experimental and random distributions were very similar but for most other groups, the distributions found were much different from the calculated random distributions.     

Enzymatic interesterification of tallow-sunflower oil mixtures

In an effort to improve the physical and/or thermal characteristics of solid fats, the enzymatic interesterification of tallow and butterfat with high-oleic sunflower oil and soybean oil was investigated. The two simultaneously occurring reactions, interesterification and hydrolysis, were followed by high-performance liquid chromatography of altered glycerides and by gas-liquid chromatography of liberated free fatty acids. The enzymes used in these studies were immobilized lipases that included either a 1,3-acyl-selective lipase or acis-9-C₁₈-selective lipase. The degree of hydrolysis of the fat/oil mixtures was dependent upon the initial water content of the reaction medium. The extent of the interesterification reaction was dependent on the amount of enzyme employed but not on the reaction temperature over the range of 50–70°C. Changes in melting characteristics of the interesterified glyceride mixtures were followed by differential scanning calorimetry of the residual mixed glycerides after removal of free fatty acids. Interesterification of the glyceride mixes with the two types of enzymes allowed for either a decrease or increase in the solid fat content of the initial glyceride mix.     

Concentration of docosahexaenoic acid in glyceride by hydrolysis of fish oil withcandida cylindracea lipase

In an attempt to concentrate the content of DHA (docosahexaenoic acid) in a glyceride mixture containing triglyceride, diglyceride and monoglyceride, fish oil was hydrolyzed with six kinds of microbial lipase. After the hydrolysis, free fatty acid was removed and fatty acid components of the glyceride mixtures were analyzed. When the hydrolysis withCandida cylindracea lipase was 70% complete, the DHA content in the glyceride mixture was three times more than that in the original fish oil. The EPA (eicosapentaenoic acid) content became almost 70% of the original fish oil. Hydrolysis with other lipases did not result in an increase in the DHA content in the glyceride mixtures. Hydrolysis of DHA-rich tuna oil (DHA content is about 25%) withCandida cylindracea lipase resulted in 53% DHA in the glyceride mixture. The EPA content, however, remained close to that of the original tuna oil. In this report, the acyl chain specificity of lipases is evaluated in terms of hydrolysis resistant value (HRV). HRV is the ratio between the DHA contents in the glyceride mixture of hydrolyzed oil and original oil. HRV clearly indicates differences in hydrolysis between DHA and other fatty acids (e.g., saturated and monoenoic acids).     

The triglyceride composition of linseed oil

The triglyceride composition of linseed oils obtained under different ecological conditions and having different fatty acid compositions was determined by a combination of several chromatographic techniques. The triglyceride mixture was first separated in 8 fractions of different polarity by reversed-phase paper chromatography. Each glyceride fraction was then separated in a partition chromatographic system as the triglyceride coordination complexes with silver ions into individual compounds. The fatty acid compositions of the original oil, single glyceride fractions, and individual triglycerides were determined by gas-liquid chromatography. The molar ratio between the two neighboring glyceride fractions was determined by relating the fatty acid composition of each fraction to the fatty acid composition of their sum. The triglyceride composition of the total oil was then calculated from these results. The presence of 18–19 triglycerides was ascertained in the samples studied, and the molar concentration of each glyceride was estimated. Linseed oil contains only triunsaturated and monosaturated-diunsaturated triglycerides. Within each of these types the fatty acid distribution is close to random. At the same time, the content of some triglycerides departed regularly from a random pattern. A method for calculation of linseed oil triglyceride composition from the fatty acid composition is given. The same general pattern of glyceride formation in linseed is followed regardless of ecological conditions; therefore, the qualitative and quantitative triglyceride composition reflects the differences in fatty acid composition of linseed oil.     

The effect of dietary fat on the glyceride structure of rat carcass fat

Carcass fats were obtained from weanling rats fed a complete diet for 8 weeks, which consisted of 2% cottonseed oil and 10% of the following fats: (1) corn oil; (2) the fatty acids of corn oil; (3) triricinolein; (4) ricinoleic acid; (5) the hydrogenated fatty acids of castor oil ; and (6) commercial hydrogenated shortening. The fats were subjected to both pancreatic lipase and nonspecific hydrolysis ; the resulting acids converted into methyl esters by conventional methods, and subjected to gas Chromatographie analysis. From these data, the positional distri-bution of the component fatty acids, glyceride types, and isomeric forms were calculated. The results indicated a preferential placement of un-saturated acids in the 2- position of the carcass triglycerides and that the carcass fat composition in terms of unsaturated (U) and saturated (S) fatty acid composition is not greatly influenced by the S and U compositions of the dietary fat. It was found that hydroxy acids or their tri-esters are metabolized much the same as are normal triglycerides and exert no particular in-fluence upon the fat structure of the rat. Some type of relationship between the dietary U and the U₃ in the carcass fat appears to be present. The glycerides of the carcass fats examined here are essentially a random mixture of the major glyceride types, but the isomeric forms (SUS, S SU, USU and UUS) are a definite non-random mixture. Carried out at the Food Res. Div., Armour & Co., and at The Burnsides Research Laboratory under research grant No. EF 225 from the National Institutes of Health, U. S. Public Health Service, and Deparmtent of Health, Education, and Welfare.     

Effect of Interesterified Fats and Isolated trans Fatty Acids on Serum Lipid Classes in Cholesterol-Bile Salt Stressed Rats

Interesterified plastic fat products based on a) sal fat and groundnut oil (30: 70, w/w;P/S,0.8) (sal-GNO);b) vanaspati, partially hydrogenated vegetable oil and groundnut oil (40:60; P/S, 1.0; isolated trans fatty acid content 17%) (vanaspati-GNO);c) cottonseed oil (P/S, 1.5) (CSO) and d) sal fat and safflower oil (50:50, P/S, 1.3) (sal-saff) were prepared using dry sodium methoxide as the catalyst. The products had slip points of 33?34°C. These products, their original blends, safflower oil (P/S, 8.5) and a blend of vanaspati and safflower oil (50 : 50, P/S, 2.8 and isolated trans fatty acid content 22%) (vanaspati-saff) were tested for hypolipidaemic effect (serum total cholesterol, total lipids, triglycerides and phospholipids) in cholesterol-bile salt stressed rats. All the test fats having linoleic acid content varying from 21.9-76.6% and P/S ratio from 0.8 to 8.5 and fed at 10% level providing 23% calorie were found to be superior to vanaspati (P/S, 0.16, 3% linoleic, 43% isolated trans fatty acids). P/S ratio of 1.5 and linoleic content of 30% in fat were found to be optimum for maximum hypolipidaemic effect at above dietary regimen. Fat and cholesterol contents of liver of animals, fed test lipids were significantly lower than that of animals fed vanaspati. when linoleic acid content of the product was comparatively low (e.g. sal-GNO, 25%), the process of rearrangement reduced the cholesterol content of liver. With high linoleic acid content (CSO, 48.2% or sal-saff, 40.4%) interesterification was without any effect. Hypolipidaemic effect of interesterified products was similar to that observed with original materials. Thus, the above quality of a fat having characteristics within the above ranges does not depend upon the distribution of acyl groups in glyceride molecules. Isolated trans fatty acids behaved more or less like a saturated fatty acid in elevating serum lipids. Vanaspati was found to be highly hyperlipidaemic.     

Studies on some chemical aspects of kusum oil

Chemical methods, chromatography and infrared spectroscopy have been applied to ascertain the location and nature of the cyanogenic compounds in kusum oil. Observations indicate the cyanogenic compounds to be a part of glyceride molecules in which one of the hydroxyl groups of the latter is bonded to the cyanogenic compound through an ether linkage. Chromatographic behavior of the isolated cyanogenic compounds further indicates that at least two glyceride molecules are involved. These glycerides are predominantly esterified with saturated fatty acids.     

Determination of oil content of seeds by NIR: Influence of fatty acid composition on wavelength selection

The oil content of nine different types of oilseeds has been determined by near-infrared reflectance (NIR) spectroscopy. A Northstar computer was used to select the wavelengths that best represent the oil content in these seeds. Selected wavelengths were often in the same area of the spectrum, but calibrations differed with respect to the number of wavelength points required and their order of selection. Wavelength assignments for typical functional groups in fatty acids are discussed. The fatty acid composition and the predominant fatty acid component appeared to influence the wavelengths used for the estimation of oil content in each seed type. The mathematical treatments used appeared to affect absorption maxima of all seed types. Spectra of seed oils and their fatty acids indicated variation and closeness of absorption maxima. Paper No. 649 of the Canadian Grain Commission, Grain Research Laboratory, 1404-303 Main Street, Winnipeg, Manitoba, R3C 3G8, Canada. Presented at the 79th annual meeting of the American Oil Chemists’ Society on May 10, 1988, Phoenix, Arizona, U.S.A.     

Phospholipid and fatty acid composition of Bulgarian nut oils

The phospholipid and fatty acid composition of three Bulgarian nut oils were investigated. Phospholipids were separated by Folch′s method and two-directional thin-layer chromatography. Their content was determined spectrophotometrically. Phospholipids were present at levels of 0.8% in almond oil, 2.8% in hazelnut oil, and 0.9% in walnut oil. Phosphatidylcholine (18—50%), phosphatidylinositol (18—45%), and phosphatidylethanolamine (8—16%) were found to be the major components. Small amounts of phosphatidylserine, phosphatidic acids, phosphatidylglycerols, lysophosphatidylcholine, and lysophosphatidylethanolamine were also detected. The fatty acid composition of glyceride oils and of the four main phospholipids, namely phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidic acids was identified by capillary gas chromatography of their methyl esters. The predominant fatty acid present in almond and hazelnut oils was linoleic (83.2% and 80.8%, respectively). Oleic acid (18.7%), linoleic acid (48.5%), and linolenic acid (15.8%) were the major components in walnut oil. Higher quantities of saturated fatty acids (27.8—81.2%) were found to be in the phospholipids than in the corresponding oils (9.5—16.7%).     

The application of liquid-liquid extraction to the fractionation of coconut oil

Summary In order to investigate the value of liquid-liquid extraction as a means of studying the glyceride structure of fats and oils, coconut oil was subjected to liquid-liquid extraction with ethanol, using both the batch method and a continuous counter-current extractor. Both methods yielded essentially similar results. Extraction effected the separation of coconut oil into fractions different in composition from the original oil, but they were not simple enough in composition to aseertain the glyceride structure of the oil. On the contrary, all the glyceride fractions contained at least six and in most cases all of the eight fatty acids present in coconut oil. In general, proportions of the lower fatty acids (caproic to lauric) in the glyceride fractions decreased as extraction progressed, whereas the proportions of the higher fatty acids increased. These facts were in agreement with changes in solubility, neutral equivalents, refractive indices, and iodine numbers. Condensed from theses presented by M. H. Menaker and by William R. Fish to the faculty of the Graduate School of Pennsylvania State College in partial fulfillment of the requirements for the degree of Doctor of Philosophy. This work was supported in part by a grant established by General Mills, Inc.     

DC-Trennung von Ricinusölfettsäure-Partialglyceriden

Thin-Layer Chromatographic Separation of Partial Glycerides of Castor Oil Fatty Acids Partial glycerides of castor oil fatty acids and hydrogenated castor oil fatty acids were prepared by esterification or glycerolysis and fractionated, together with commercial products, by TLC (especially by two-dimensional technique) on silicagel 60 precoated plates. By comparison of the two-dimensional chromatograms of the partial esters of castor oil fatty acids with synthetic standards, such as partial glycerides of ricinoleic, di- and tri-ricinoleic acids, estolides of castor oil fatty acids esterified to partial glycerides, and partial esters of castor oil fatty acids with 1,3-propanediol, the substances that could be identified were partial glycerides of ricinoleic, diricinoleic and triricinoleic and tetraricinoleic acids as well as partial glycerides, which contained, in addition to ricinoleic, diricinoleic and triricinoleic acids, fatty acids without hydroxyl groups as terminal estolide chain. The TLC enables an insight into the complex character of the glyceride composition of partial glycerides of castor oil fatty acids.     

Fatty acid composition of triglycerides and phosphoglycerides during growth inGlomerella cingulata

The fatty acid composition of triglycerides and phosphoglycerides accumulated at selected ages during the growth ofGlomerella cingulata was investigated. Glyceride accumulation was taken as mg glyceride/mg N and the nitrogen content of the fungus at the ages investigated was used as an index of growth. The fatty acids produced were identified by comparing their retention times on gas liquid chromatography with that of known standards. The results showed that whereas total glyceride and fatty acid content varied from age to age, the fatty acid composition at the various ages remained the same.     

Digestion and absorption of free and esterified fish oil fatty acids in rats

This study was designed to test the hypotheses that digestibility and post-absorption metabolism of fish oil are influenced by impaired lipolysis and by the stereospecific composition of its triacylglycerols. Male Wistar rats were fed nonpurified diets containing one of the following fat sources: 9% native fish oil (NFO), 9% autorandomized fish oil (RFO), 8.1% fish oil-derived free fatty acids (FO-FFA) plus 0.9% glycerol, or 9% soybean oil (SO) as a reference fat. In a 24-day balance study, apparent digestibility of total dietary fat averaged 93.1% in the SO, NFO and RFO groups, and 90.9% in the FO-FFA group. Randomization of fish oil had no effect on apparent digestibility of individual fatty acids. In rats fed FO-FFA, apparent absorption of saturated and monounsaturated fatty acids was lower when compared to the NFO and RFO groups. Feeding the FO-FFA diet tended to increase plasma triglyceride content. The hypocholesterolemic effect of polyunsaturated n−3 fatty acids was not influenced by the dietary source. Similar effects on fatty acid profiles of plasma and liver phospholipids were caused by the NFO, RFO and the FO-FFA diets. We conclude that once polyunsaturated n−3 fatty acids are absorbed, their effect on lipid metabolism is not determined by the dietary source.     

On the Mechanism of the Thermal Polymerization of Linseed Oil

The monomeric and polymeric glycerides present in thermally polymerized linseed oils can be separated quantitatively by molecular distillation. Analysis of the fatty acids of monomeric and polymeric glycerides indicate the occurence of intra- and intermolecular condensations respectively. Whereas in the former reaction, leading to the formation of bicyclic, dimeric fatty acid groups within the orginal glycerides, no increase in the molecular weight of the oil takes place, in the latter one, characterized by an increase in the molecular weight, fatty acids of different glyceride molecules are involved. It is shown, however, that the overall increase in molecular weight is due to the dimeric glycerides which are formed by interesterification reactions between glyceride monomers containing dimeric fatty acid groups, the latter resulting from intramolecular condensation.     

Studies in Acidolysis

Acidolysis of a natural triglyceride oil with free fatty acids of different chain length has been studied to find out the degree of interchange of fatty acids, the mode of distribution of the free acids incorporated in the triglyceride molecules and the glyceride composition of the oil after acidolysis. The results as determined by gas-liquid chromatography and pancreatic lipase hydrolysis indicate that the degree of interchange of fatty acids depends on the chain length of the free acids, and the incorporation of the free acids in the glyceride molecules occurs in a purely random manner. Glyceride compositions of the oils are also randomly rearranged after acidolysis reaction.     

Fatty acid composition and glyceride structure of piglet body fat from different sampling sites

Pigs were slaughtered at 16 weeks of age, and fat samples were obtained from outer and inner shoulder, outer and inner loin, and kidney. Fatty acid composition and glyceride type of distribution were determined. Glyceride structure was determined by pancreatic lipase hydrolysis. There were highly significant differences in fatty acid composition between sites. Fatty acids containing less than 18 carbon atoms were preferentially incorporated in the internal positions of the glycerides. The content of saturated fatty acids and fatty acids containing less than 18 carbon atoms at the 2-position of shoulder and loin glycerides was higher than in kidney glycerides. Differences in glyceride types were noted between sites.     

On the composition of Iranian olive oil

Two samples of virgin olive oil and one sample of hexane-extracted husk oil coming from Iran were examined. The analyses included physical and chemical characteristics, the composition of total fatty acids and fatty acids at the glyceride 2-position by gas liquid chromatography (GLC) of methyl esters, the triglycerides composition calculation according to Vander Wal theory, the separation of the alcoholic fractions (sterols, 4-methylsterols, triterpene alcohols, triterpene dialcohols and aliphatic alcohols) of the unsaponifiable matter by thin layer chromatography (TLC), the quantitation and the composition of these fractions by GLC of TMS derivatives. The results were in line with data from literature for olive oils of different origin, with the exception of: a high content of unsaponifiable matter (1.75 and 1.95% for virgin oils, 5.33% for husk oil); a high amount of sterols for husk oil (562 mg/100 g oil); a low content of SE 30 apparent β-sitosterol for husk oil (91.1%); a low amount of triterpene dialcohols (1 mg/100 g oil) and triterpene alcohols (78 and 91 mg/100 g oil) for virgin oils; a content of cycloartenol (60.2–66.9%) higher than the 24-methylenecycloartanol one (22.8–26.6%; a content of C₂₄ linear saturated alcohol (33.9–38.0%) slightly higher than the C₂₆ alcohol one (29.3–32.8%).     

Separation of eicosapentaenoic acid and docosahexaenoic acid in fish oil by kinetic resolution using lipase

The objective of this study was to investigate the use of lipases as catalysts for separating eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in fish oil by kinetic resolution. Transesterification of various fish oil triglycerides with a stoichiometric amount of ethanol by immobilized Rhizomucor miehei lipase under anhydrous solvent-free conditions resulted in a good separation. When free fatty acids from the various fish oils were directly esterified with ethanol under similar conditions, greatly improved results were obtained. By this modification, complications related to regioselectivity of the lipase and nonhomogeneous distribution of EPA and DHA into the various positions of the triglycerides were avoided. As an example, when tuna oil comprising 6% EPA and 23% DHA was transesterified with ethanol, 65% conversion into ethyl esters was obtained after 24 h. The residual glyceride mixture contained 49% DHA and 6% EPA (8:1), with 90% DHA recovery into the glyceride mixture and 60% EPA recovery into the ethyl ester product. When the corresponding tuna oil free fatty acids were directly esterified with ethanol, 68% conversion was obtained after only 8h. The residual free fatty acids comprised 74% DHA and only 3% EPA (25:1). The recovery of both DHA into the residual free fatty acid fraction and EPA into the ethyl ester product remained very high, 83 and 87%, respectively.     

Structure of bovine milk fat triglycerides

The triglycerides of bovine milk fat globules were isolated and separated into short, medium and long chain lengths by thin-layer chromatography. The molecular weight distribution and the fatty acid composition of the component triglycerides was then separately determined by gas chromatography following argentation-thin-layer and preparative gas chromatography. Some 38 triglyceride types (28% of total), of which there could be up to 6 isomers, were specifically identified and quantitatively estimated. The quantitative estimates for the rest of the milk fat triglycerides were limited to much more complex glyceride groups. The results confirm the earlier claim that butyric and caproic acids occur in milk fat almost exclusively in combination with medium and long chain fatty acids. Presented in part at the AOCS Meeting, Philadelphia, October, 1966.