Characterization of minor constituents in commercial oleic acid

Minor constituents were isolated from a mixture of commercial oleic acid manufactured from beef tallow by 10 different companies. Silicic acid was used as an adsorbent to isolate the minor constituents. They were first separated into acidic and nonacidic fractions. Each fraction was then separated into numerous subfractions by stepwise gradient elution liquid chromatography, using silicic acid as the adsorbent. The subfractions which had an adverse effect on the color stability of oleic acid during heating were characterized with functional group analysis, elemental analysis and IR spectrophotometry. The minor constituents amounted to ca. 1.18% of the commercial oleic acid. They were complex mixtures with multiple functional groups. Some of the subfractions contained 2\s-3 times as much oxygen in the molecule as oleic acid. They had molecular weights ranging from 308 to 830 which are from monomers to trimers of oxidized oleic acid. These minor components contained carbonyl, ester and hydroxyl groups and double bonds. Some of the nonacidic minor constituents may contain amide groups. Most of the acidic subfractions were dark red, viscous liquids and the nonacidic subfractions were dark green or greenish-brown, semisolid substances. A relationship was established that the greater the polarity of the minor constituents, the greater is its adverse effect on the color stability of oleic acid during heating. Paper of the Journal Series, New Jersey Agricultural Experiment Station, Cook College, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903.     

Origin of minor constituents of commercial oleic acid

Fatty acids were prepared from beef tallow in the laboratory by alkalization and acidification under a nitrogen atmosphere at temperatures below 100 C. The minor constituents in the beef tallow fatty acids were isolated by the silicic acid method as described previously. They were fractionated by silicic acid liquid column chromatography and characterized by chemical functional group analyses, elemental analyses and infrared spectrophotometric methods. The results suggest that the minor constituents in commercial fatty acids were partly present in the original raw material of beef tallow and were partly formed as artifacts during the manufacturing process. Paper of the Journal Series, New Jersey Agricultural Experiment Station, Cook College, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903.     

Main constituents of rapeseed lecithin

Commercial rapeseed lecithin has been analyzed after separation by silicic acid column chromatography. Besides neutral oil (40%), four major constituents have been found, viz., phosphatidyl ethanolamine (18%), phosphatidyl inositol (8%), phosphatidyl choline (16%) and sterol glycosides (8%). Among the minor fractions lysophosphatidyl ethanolamine accounts for about 2%. The phosphatides are characterized by low erucic acid content and the major fatty acids are palmitic, oleic and linoleic acids.     

The lipid composition of karaka seeds (corynocapus laevigatus)

The kernels of karaka seeds(Corynocapus laevigatus) contained 9.6% oil by wt. The lipid constituents were characterized by silicic acid column chromatography and thin layer chromatography, and their individual fatty acid compositions by gas liquid chromatography. Of the seed oil, triacylglycerol was the major component which contained high proportions of linoleic (45%) and oleic (26%) acids. The major component of husk oil (0.9% of husk by wt) was polar lipid (glycolipids and pigments).     

Changes in the structure of soybean triacylglycerols due to heat

Commercially refined soybean oil was heated at 180 C for 50, 70 or 100 hr with aeration. The triacylglycerol fractions separated from the oils by column chromatography on silica gel were fractionated further by silicic acid thin layer chromatography (TLC), and species compositions were determined by argentation TLC and lipase hydrolysis. There was a decrease in the absolute amounts of the triacylglycerols with longer heating periods, such as 21% for 50 hr and 42% for 100 hr. Relatively large changes occurred in the proportion of the molecular species of the triacylglycerols during heating; there was an increase in the more saturated species, 1–4 double bonds, and a decrease in species containing 5–7 double bonds. Although these changes occurred in the percentage of each triacylglycerol species, the positional distribution of the fatty acids in the 2-position remained virtually unchanged throughout heating. Oleic and linoleic acids were commonly found in the 2-position of the acylglycerol moiety, whereas most of the palmitic and stearic acids favored esterification in the 1- and 3-positions. The results indicate that unsaturated fatty acids located in the 2-position are protected significantly from thermal oxidative decomposition.     

Effect of heat on triglycerides of corn oil

Results of a study on the effect of heating corn oil in air to a 200C temp are reported. Heated oil was separated on a silicic acid column into 8 fractions. The first four fractions, constituting about 62% original oil, were found to be unchanged triglycerides. The remaining 4 fractions constituted polymeric and degraded products of high molecular wt. Percentage losses from the respective positions in the oleo- and linoleoglyceride fractions suggest that fatty acids in primary positions are slightly more susceptible to heat than those in the 2-position. Assuming a 1,3-random 2-random distribution, triglyceride fraction in the heated oil contained 6.7% trilinolein as compared to 17.7% in fresh oil. Evidence is presented which shows presence of branching in short chain unsaturated acids and of hydroxy acids in the saponified polymeric fractions. Presented in part at the AOCS Meeting, New Orleans, 1962     

Effects of thermally oxidized triglycerides on the oxidative stability of soybean oil

Soybean oil purified by silicic acid column chromatography did not contain peroxides, free fatty acids, phospholipids or oxidized polar compounds. The purified soybean oil was thermally oxidized at 180°C for 96 hr in the presence of air. The thermally oxidized compounds (31.3%) were separated from the purified soybean oil by gradient elution silicic acid chromatography. Thermally oxidized compounds contained hydroxyl groups, carbonyl groups andtrans double bonds according to the infrared spectrum. Thermally oxidized compounds were added to soybean oil and purified soybean oil at 0, 0.5, 1.0, 1.5 and 2.0% to study the effects of these compounds on the oxidative stability of oil. The oxidative stabilities of oils were determined by gas chromatographic analysis of volatile compound formation and molecular oxygen disappearance in the headspace of oil bottles. The thermally oxidized compounds showed prooxidant effects on the oxidative stabilities of both refined, bleached and deodorized soybean oil and purified soybean oil. Duncan’s Multiple Range Test showed that thermally oxidized compounds had a significant effect on the volatile compound formatiion and oxygen disappearance in the headspace of oil at α=0.05.     

The triglycerides of sable fish (anaplopoma fimbria). II. fatty acid distribution in triglyceride fractions as determined with pancreatic lipase

Sable fish muscle lipids were fractionated on a silicic acid column with mixtures of chloroform and methanol as eluting solvents. Three main peaks containing only triglycerides were isolated; 11 additional peaks contained phosphorous. Each of the 3 triglyceride peaks was separately fractionated into 300 fractions on silica gel columns impregnated with silver nitrate. Mixtures of petroleum ether and ethyl ether were the eluting solvents. About 25 distinct fractions were isolated from each column. The fractions were characterized for fatty acid content by gas chromatography of the methyl esters. The results showed that the fractionation did not depend upon the presence of single fatty acids but upon total unsaturation. Fatty acid distribution within each fraction was determined with the use of hog pancreatic lipase, followed by thin-layer chromatography and gas chromatography. Presented at the AOCS Meeting in Houston, Texas, 1965.     

Minor components responsible for flavor reversion of soybean oil

Edible refined, bleached and deodorized (RBD) soybean oil was fractionated by silicic acid column chromatography to identify minor components responsible for flavor reversion. Minor components from oil eluted with diethyl ether/n-hexane (1:1) were compared with those from corn and canola oils. All vegetable oils contain free fatty acids, diglycerides and sterols as major ingredients in this fraction. However, unusual triglycerides consisting of 10-oxo-8-octadecenoic acid and 10-and 9-hydroxy octadecanoic acids were detected in RBD and crude soybean oils.     

Qualitative and quantitative comparison of minor constituents in different commercial oleic acids

The minor constituents from a high quality commercial oleic acid (SCOA) were isolated and fractionated by liquid column chromatography. They were chemically characterized and their effects on the color stability of oleic acid during heating were determined. The results were compared qualitatively and quantitatively with those from a mixture of commercial oleic acids (MCOA) manufactured by 10 companies. It was found that, qualitatively, SCOA and MCOA contained the same type of minor constituents. However, quantitatively, the MCOA contained 1.18% of minor constituents whereas the SCOA contained only 0.81% of minor constituents. The amount of effective minor constituents which had an adverse effect on the color stability of oleic acid during heating was 0.09% for SCOA vs 0.45% for MCOA. Paper of the Journal Series, New Jersey Agricultural Experiment Station, Cook College, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903     

New application of high pressure reversed-phase liquid chromatography in lipids

High pressure reverse-phase liquid chromatography has been used to separate saturated fatty acids, their methyl esters, polyunsaturated fatty acids, and triglycerides. Rapid separation of fatty acids differing in chain length and number of double bonds has been accomplished. Analysis time was less than 10 min in most cases. The high pressure reverse chromatography resulted in better separations of polyenoic acids than can be accomplished by conventional argentation silicic acid column chromatography. The analyses were carried out on a chemically bonded reverse phase packing, VYDAC reverse phase.     

Triacylglycerols from viper bugloss (Echium vulgare L.) seed bio‐oil

Triacylglycerols (TAG) in viper bugloss oil were isolated from raw pressed oil by silicic acid column chromatography. The obtained blend of TAG was separated by silver ion thin‐layer chromatography (TLC Ag⁺) into nine fractions, varying in terms of unsaturation level and molecular polarity. The composition of TAG in viper bugloss oil was determined by HPLC coupled with a diode‐array detector and an evaporative light‐scattering detector. The results showed that the first three fractions were combinations of TAG containing palmitic, oleic and linoleic acids. Fractions 4 and 6 contained TAG of a similar acid composition as above, but with the addition of γ‐linolenic acid. The remaining fractions (7–9) were the most varied in acid composition. They were found to contain 26–39% palmitic acid, 12–15% oleic acid, 13–41% linoleic acid 8–24% γ‐linolenic acid, 1.5–5.5% α‐linolenic acid and 1–5% stearidonic acid. The analysis of fatty acid allocation in TAG of viper bugloss lipids revealed that linoleic acid (ranging from 2 to 100%) was the only acid found in all isolated fractions. In the investigated oil, the predominant TAG included: LnLnG (11.38%), LnLnSt (11.17%), LnGSt (7.71%), LnStSt (6.19%) and LnLnLn (5.44%). Almost 86% of the TAG contained α‐linolenic acid, while γ‐linolenic and stearidonic acids amounted to 49 and 38%, respectively.     

Use of argentation column chromatography in the identification of fish oil fatty acids by GLC: Application to cod liver oil

The fatty acid methyl esters from cod liver oil have been fractionated into seven fractions, depending on degree of unsaturation, by a silver nitratetreated silicic acid column. The fractions have been analyzed by gas liquid chromatography and the components identified by usual techniques.     

Lipid metabolism ofAgaricus bisporus (Lange) sing.: I. Analysis of sporophore and mycelial lipids

The lipid components of four strains ofAgricus bisporus (Lange) Sing., the cultivated mushroom, were analyzed. Both sporophore and mycelial samples were obtained from beds in normal production. A method for obtaining mycelium free of compost was developed. Neutral lipids were separated from polar lipids by silicic acid column chromatography. Each fraction was separated by thin layer chromatography. Fatty acid methyl esters were analyzed by gas liquid chromatography and mass spectrometry. Sporophore extracts contained free sterol, free fatty acid, triglycerides, phosphatidyl choline and phosphatidyl ethanolamine. High amounts of linoleic acid were found in both neutral and polar lipid fractions. Mycelial extracts contained free fatty acids, triglycerides, phosphatidylcholine and phosphatidyl ethanolamine. No free sterol could be detected. Linoleic acid was also present in large amounts. Paper 3798 in the Journal Series of The Pennsylvania Agricultural Experiment Station.     

Isolation of a Series of Fatty Acid Components of Ongokea gore Seed (Isano) Oil and their Detailed Structural Analysis

The total oil production capacity of isano oil is estimated at about 10,000 tons annually. Previous studies of this oil revealed that it is rich in fatty acids including a conjugated diyne moiety. This makes isano oil an excellent candidate for sustainable applications development. However, only a few of its fatty acids have been isolated and identified so far. In this study, we have reinvestigated this oil by characterizing its physicochemical properties and isolating several of its fatty acids as ethyl esters for their detailed structural analysis and identification. Six ethyl esters of fatty acids constituting isanic oil were isolated by flash column chromatography and semipreparative HPLC. The detailed structural analysis of these fatty acid esters by infrared, high resolution, mass spectroscopy, and nuclear magnetic resonance (1‐D and 2‐D) allowed determining unequivocally their chemical structure. The main fatty acid component of the oil (35.7 %) was identified as isanic acid. Four minor acids were found to possess also two conjugated triple bonds, while the sixth fatty acid does not contain carbon–carbon triple bonds nor double bonds but possessed a cis epoxide function. Results obtained in this study are currently being used to explore potential applications of isano oil.     

Heat treatment of vegetable oils I. Isolation of the cyclic fatty acid monomers from heated sunflower and linseed oils

Linseed and sunflower oils were heated at 275 C for 12 hr under nitrogen. The sunflower oil was also heated in a commercial fryer at 200 C for 48 hr using a 2-hr daily cycle. The cyclic fatty acid monomers (CFAM) formed during the heat treatment of the linseed oil were isolated by a combination of saponification, esterification, column chromatography on silicic acid and urea fractionation. The isolated CFAM fraction was 99% pure, the balance being some 12:2ω6. Another step was necessary to isolate the CFAM from heated sunflower oils. The urea adduct fractionation resulted in the isolation of a nonurea adduct fraction which contained a mixture of CFAM and 18:2ω6. These were further separated using high performance liquid chromatography (HPLC) on a C18 reverse phase column. Each fraction was analyzed by gas liquid chromatography and hydrogenated to determine the content of the C18 straight chain fatty acids. Presented in part at the AOCS meeting in May 1985 in Philadelphia, PA.     

Isolation and identification oftrans-3,5-dimethoxystilbene from high quality tall oil fatty acids by liquid chromatography and mass spectrometry

trans-3,5-Dimethoxystilbene has been isolated from high quality tall oil fatty acids (unsaponifiables 1.5% maximum, rosin acids 1.5% maximum), using liquid column chromatography and low temperature solvent fractional crystallization. The structure of this compound was determined with the aid of IR, mass and NMR spectrometry. Thetrans-3,5-dimethyoxystilbene was found to be responsible for the development of a red color during the epoxidation of the tall oil fatty acids.     

Spectrophotometric analysis of tall oil rosin acids

Summary About half of the rosin acids in whole and distilled tall oil consist of abietic and neoabietic acids, as distinguished from hydroabietic acids, dehydroabietic acid, and the pimaric acids. In this respect the tall oil rosin acids are similar to those from gum or wood rosin. This was established by spectrophotometric analysis of the rosin acids from whole tall oil, double distilled tall oil, rosin acids crystallized from tall oil, and rosin acids separated from tall oil by fractional distillation. The rosin acids crystallized from tall oil contained the highest percentage of abietic acid, but the sum of abietic and neoabietic acids was only slightly higher. The rosin acids from acid refined tall oil contained appreciably less abietic and neoabietic acid than the others. Before spectrophotometric analysis the rosin acids were isolated from the tall oils in about 95% yield by cyclohexylamine precipitation.     

Phospholipids of tuna white muscle

The composition of the lipids from the white muscle of five tuna fish has been determined. Total extractable lipid varied from 0.5%–10.3% of the tissue wet weight; phospholipid content ranged from 0.3%–0.6%. The separation of the phospholipid components was made by column chromatography with activated silicic acid and stepwise elution, with increasing concentrations of methanol in chloroform. The components were identified by chemical tests and infrared (IR) spectra. Tuna white musele contained an average of 0.5% phospholipid on wet weight basis; 23% was cephalin, 54% lecithin, 8% sphingomyelin, 2% phosphoinositide, with small amounts of unidentified components. Ten to 30% of the lecithin and cephalin fractions were in the form of plasmalogens. The gas-liquid chromatographic analyses of the 12–22 carbon fatty acids of the lecithin, cephalin, and neutral fractions are presented. The cephalins were characteristically high in stearie acid and low in palmitic acid, in contrast to the lecithins.     

Fatty acids of cows' milk. B. Composition by gas-liquid chromatography aided by other methods of fractionation

A fresh sample of cows' milk was converted directly to the methyl esters by methanolysis and the esters were fractionated into eleven distilled fractions and an undistilled portion. The latter, which contained the bulk of the polyunsaturated and long chain esters, was further fractionated by adsorption chromatography on a silicic acid column. Each fraction from the distillation and adsorption chromatography was analyzed by gas-liquid chromatography on columns containing polyester stationary phases of different polarity. Twenty-seven minor components, including some not previously reported, were present each in less than 0.1%. The fatty acid distribution of the major components fell within the range generally reported. Presented at the 53rd Meeting of the American Oil Chemists' Society, October 17–19, 1960, New York. Eastern Utilization Research and Development Division, Agricultural Research Service, United States Department of Agriculture.