Showing papers in "Journal of the American Oil Chemists' Society in 1960"
TL;DR: An improved distillation method is described for the quantitative determination of malonaldehyde in foods containing oxidized fats and a high correlation of TBA numbers with rancid odor in cooked meats was established.
Abstract: An improved distillation method is described for the quantitative determination of malonaldehyde in foods containing oxidized fats. The procedure is compared with other methods in current use for the determination of malonaldehyde. A high correlation of TBA numbers with rancid odor in cooked meats was established.
2,710 citations
TL;DR: Adsorption chromatography on thin layers of silicic acid or alumina provides a new and highly efficient analytical tool for the rapid separation of lipids according to classes of compounds as discussed by the authors.
Abstract: Adsorption chromatography on thin layers of silicic acid or alumina provides a new and highly efficient analytical tool for the rapid separation of lipids according to classes of compounds.
386 citations
TL;DR: In this article, the application of thin-layer adsorption chromatography to the fractionation of complex lipid mixtures into classes was discussed, and further work has been done on the use of thin layer chromatography for this purpose.
Abstract: Further work has been done on the application of thin-layer adsorption chromatography to the fractionation of complex lipid mixtures into classes.
367 citations
TL;DR: In this paper, a silicic acid chromatographic adsorption column technique was described, which was effective in separating methyl esters from unsaponifiables such as sterols, pigments, etc., and free acids.
Abstract: Methyl esters were prepared from cholesteryl esters, phospholipids, and glycerides in substantially quantitative yields by methanolysis with large excess of sodium or potassium methoxide in absolute methanol. A silicic acid chromatographic adsorption column technique was described, which was effective in separating methyl esters from unsaponifiables such as sterols, pigments, etc., and free acids. Conditions for complete methanolysis of glyceride fats and oils requiring only 5 min. of reflux time were described. Quantitative conversion of fatty acids to methyl esters was accomplished by direct esterification with absolute methanol containing 4% HCL or H2SO4 and by methylation with diazomethane.
266 citations
TL;DR: In this paper, the proportions of the glyceride types and isomeric forms in some fats in which C16−C18 chains are greatly in excess can be determined by calculations based on a) the percentage of saturated acyl groups in the whole fat, b) the proportion of saturated groups in 2-monoglycerides which can be derived from the fats by hydrolysis, and c) the assumption that all the saturated and unsaturated groups (S and U) present in each of the three positions in the molecules are dispersed therein at random, and d
Abstract: Evidence has been presented that the proportions of the glyceride types and isomeric forms in some fats in which C16−C18 chains are greatly in excess can be determined by calculations based on a) the percentage of saturated acyl groups in the whole fat, b) the percentage of saturated groups in the 2-monoglycerides which can be derived from the fats by hydrolysis, c) the assumption that all the saturated and unsaturated acyl groups (S and U) present in each of the three positions in the molecules are dispersed therein at random, and d) the assumption that the proportions of S and U in the 1-positions are identical with those in the 3-positions. The method may apply to all predominantly C16−C18 fats and to other fats as well.
187 citations
TL;DR: In this paper, the authors analyzed seed oils from 37 plant species in 18 families by the isomerization method and found that the variability encountered is evidenced by the range in content of component acids: from 0 −23% for apparent linolenic acid, from 8 −74% for obvious linoleic acid and from 2 −88% for oleic acid.
Abstract: Seed oils from 37 plant species in 18 families have been analyzed for fatty acid composition by the isomerization method. The variability encountered is evidenced by the range in content of component acids: from 0–23% for apparent linolenic acid, from 8–74% for apparent linoleic acid, and from 2–88% for apparent oleic acid. Dimorphecolic acid has been found to the extent of approximately 60% in a second species ofDimorphotheca, D. pluvialis (L.) Moench, and in the closely related species,Osteospermum ecklonis (DC.) T. Norl.O. spinescens Thunb. contained instead 30% of a conjugated triene, presumably the same as the 8,10,12-octadecatrienoic reported from the relatedCalendula officinalis L. Oils rich in monoenoic acids are mostly in the Umbelliferae and Araliaceae and presumably contain petroselinic acid as well as oleic.
140 citations
81 citations
TL;DR: Findings suggest that both hepatic parenchymal and Kupffer cells participate in the removal of chylomicra; the paren chymal cell has the greatest role.
Abstract: During alimentary lipemia induced in dogs by the feeding of saturated or unsaturated fats no significant alteration occurred in phagocytic function as indicated by colloidal carbon removal and colloidal gold tissue distribution studies. The cellular distribution of intravenously administered triglyceride indicated that most of the injected triglyceride was found in the isolated hepatic parenchymal cell. The distribution of an intravenously administered free cholesterol emulsion indicated initial localization in the parenchymal cell and a later elevation in the Kupffer cell. These findings suggest that both hepatic parenchymal and Kupffer cells participate in the removal of chylomicra; the parenchymal cell has the greatest role. The late elevation in cholesterol content of the Kupffer cell is indicative of a metabolic or excretory function of these cells in cholesterol metabolism.
67 citations
TL;DR: The interference of certain unsaturated hydroxy acids in the Durbetaki method of epoxide determination has been demonstrated by measurement of the near infrared spectra of samples before and after treatment with anhydrous ethereal hydrogen chloride as discussed by the authors.
Abstract: The interference of certain unsaturated hydroxy acids in the Durbetaki method of epoxide determination has been demonstrated. The concentrations of these constituents were determined concurrently with those of epoxy components by measurement of the near infrared spectra of samples before and after treatment with anhydrous ethereal hydrogen chloride. The individual hydroxy esters were separated and isolated from samples of mixed esters by thinlayer chromatography. GLC of these esters resulted in their alteration to conjugated trienoates and gave proof of their conjugated diene hydroxyl structure. Thin-layer chromatographic and infrared studies verified theTrans-trans diene unsaturation of the acid fromDimorphotheca aurantiaca oil and showed that the other hydroxy compounds examined have acistrans diene system. These data suggest that the seed oils ofArtemisia absinthium, Calliandra eriophylla, Balanites aegyptica, Cosmos bipinnatus, and Helianthus annuus contain 9-hydroxy-trans-10-cis-12- and 13-hydroxy-cis-9-trans-11-octadecadienoic acids.
67 citations
TL;DR: In this article, a cup method was used to determine the permeability of cocoa butter, highly hydrogenated cottonseed oil, mixtures of highly-hydrated cottonseed oils and cottonseed oils, chocolate liquor, and sweet milk chocolate to water vapor.
Abstract: Films of cocoa butter, highly hydrogenated cottonseed oil, mixtures of highly hydrogenated cottonseed oil and cottonseed oil, chocolate liquor, and sweet milk chocolate were prepared; and their permeability to water vapor was determined by the cup method. The permeability constant was calculated in terms of grams of water diffusing through a centimeter cube in one second under a vapor pressure gradient of one millimeter of mercury across the cube.
61 citations
TL;DR: In this paper, the rate of oxygen uptake in linoleic acid and methyl linoleate emulsions in aqueous buffer solutions was studied. And the results showed that the oxidation rates increased with an inerease in the pH of the buffer solution.
Abstract: Autoxidation of linoleic acid and methyl linoleate emulsions in aqueous buffer solutions was studied by the rate of oxygen uptake. The oxidation rates of methyl linoleate emulsions increased with an inerease in the pH of the buffer solution. With linoleic acid, oxidation rates rose until the increase reached its peak at pH 5.50 and then decreased gradually to a minimum at pH 8.00.
TL;DR: In this paper, a recording refractometer is used to monitor the concentration of solutions issuing from the extractor for an equal mixture of linoleate and linolenate, which is used for the bromination-debromination process.
Abstract: Acetonitrile-pentane-hexane makes a desirable solvent system for preparation of pure methyl esters because of its immiscibility, selectivity toward unsaturation, low boiling point, stability, and ease of recovery. Since separated esters are removed from the apparatus dissolved in the pentane-hexane layer, successive batches may be fractionated without removing the acetonitrile layer from the instrument. Applications have been illustrated for the preparation of methyl linolenate from an 85% linolenate concentrate, methyl linoleate from safflower esters, and methyl arachidonate from pig liver lipids. This procedure provides a source of “natural” fatty acids with the double bond configuration unchanged, in contrast to those from the conventional bromination-debromination process. Automation of the process is completed by use of a recording refractometer which monitors concentration of solutions issuing from the extractor. Resolutions to be anticipated with lesser numbers of extraction tubes than 200 are calculated for an equal mixture of linoleate and linolenate.
TL;DR: Following injection of Tilapia mossambica with acetate-1-C14, their fatty acids were isolated, fractionated, and degraded, revealing a distribution of carbon-14 similar to that found in similar studies on mammals.
Abstract: Following injection ofTilapia mossambica with acetate-1-C14, their fatty acids were isolated, fractionated, and degraded. The high content of linoleic and arachidonic acids was evidently derived from the diet. Degradation of these acids revealed a distribution of carbon-14 similar to that found in similar studies on mammals.
TL;DR: In this article, a range of operating variables used in this work, including increased agitation and pressure, decreased catalyst activity, decreased concentration of metal in oil and on carrier, and with decreased temperature.
Abstract: Palladium-on-carbon catalysts are exceedingly active for the hydrogenation of natural unsaturated oils when very mild conditions are used. Selectivity is usually good, andtrans content can be adequately controlled by the proper choice of conditions. In the range of operating variables used in this work,trans formation is lessened with increased agitation and pressure, decreased catalyst activity, decreased concentration of metal in oil and on carrier, and with decreased temperature. Some shortening stocks were obtained which have good physical properties, as expressed by their dilatometric curves.
TL;DR: In this paper, the separation of fatty amines was carried out with nonpolar substrates on solid supports of Chromosorb and chromosorb W, which were previously treated with potassium hydroxide to overcome adsorptivity.
Abstract: The separation of fatty amines has been carried out with nonpolar substrates on solid supports of Chromosorb and Chromosorb W, which were previously treated with potassium hydroxide to overcome adsorptivity. In this manner well-resolved symmetrical peaks are obtained. Untreated supports give peaks which trail and prohibit precise quantitative measurements. Both Apiezon L on Chromosorb W and Silicone Grease on Chromosorb have proved effective, the latter at 176°C. and the former at 225°C. Relative detector sensitivity factors have been determined for the amines C8 to C18, thus permitting accurate analyses. The relative response for primary alkyl fatty amines is a linear function of molecular weight.
TL;DR: When autoxidized fatty esters and purified fatty hydroperoxides were decomposed in the absence of oxygen at 210°C, the principal reaction was dimerization of the fatty acid chains with elimination of the hydroperoxide groups as mentioned in this paper.
Abstract: When autoxidized fatty esters and purified fatty hydroperoxides were decomposed in the absence of oxygen at 210°C., the principal reaction was dimerization of the fatty acid chains with elimination of the hydroperoxide groups. Dimers isolated by molecular distillation (60 to 90% of the polymer) have approximately 1 mole hydroxyl, 0.5 mole carbonyl, and two double bonds per mole of dimer. Diene conjugation in the dimers from polyunsaturated fat hydroperoxides varied from 10 to 23%. The infrared spectra of the dimers were similar to those of the original fatty esters except for one striking band at 2.9 μ, which is attributed to the secondary hydroxyl group. Thecis-trans diene in the polyunsaturated hydroperoxides was isomerized to thetrans-trans configuration on dimerization. The methyl oleate hydroperoxide dimer showed only absorption for isolatedtrans double bond. The dimer was not split either by catalytic hydrogenation or by hydrogen iodide, indicating a carbon-carbon bond between the monomer units. On oxidation with permanganate and periodate, the dimeric acids behaved like a monounsaturated mixture containing double bonds in the C6, C7, C8, C9, and C10 positions in the oleate dimer and in the C8, C9, and C10 positions in the safflower ester dimer. Although the dimers showed no peroxidic oxygen iodometrically with potassium iodide, a reduction occurred with hydriodic acid that may indicate the presence of intramolecular peroxide groups and/or allylic alcohol or carbonyl groups. Bromination with N-bromosuc-cinimide and dehydrobromination with N,N-dimethyl aniline produced no aromatization. Subsequent oxidation of the dehydrobrominated dimer yielded 2.6% residue, which was not aromatic. This evidence indicates that the dimer does not have a six-membered cyclic structure. Dimerization of the hydroperoxides is suggested as occurring through alkyl or alkoxy hydroperoxide radicals to give carbon-carbon linked fatty acid dimers and some higher polymeric units.
TL;DR: Gas-liquid chromatography, several versions of paper chromatography and alkaline isomerization have been applied to one preparation of Chlorella fatty acid methyl esters as mentioned in this paper.
Abstract: Gas-liquid chromatography, several versions of paper chromatography, and alkaline isomerization have been applied to one preparation ofChlorella fatty acid methyl esters. GLC outranks other methods in rapidity, reproducibility, and resolving power. The presence of nonvolatile components in the sample can lead to erroneous results. Among PC methods which might arise from autoxidation and polymerization are detected. Esters or acids with 14 or fewer C atoms should be analyzed as nonvolatile derivatives. AI, as used here, introduces a systematic error in the determination of linoleic and linolenic acids. The quantitative results of the methods are in agreement for the major components, which all belong to the C10 and C18 series. A number of minor components have been revealed by GLC and/or PC. They are tentatively identified as
TL;DR: In this article, the authors found that the increase in the nonvolatile carbonyl content of freshly deodorized oils was proportional to the peroxide value of the oils before deodorization.
Abstract: Oxidation prior to deodorization was shown to be detrimental to the flavor and oxidative stability of soybean oil. The increase in the nonvolatile carbonyl content of freshly deodorized oils was proportional to the peroxide value of the oils before deodorization. Rate of loss of flavor and oxidative stability of the oil were related to the extent of carbonyl development. All oils, whether or not they had been submitted to any known oxidation, contained some nonvolatile carbonyls. The loss in stability was not due to a loss of the antioxidant tocopherol.
TL;DR: In this paper, a procedure was developed for the quantitative estimation of monoglycerides in terms of their constituent fatty acids by mesylated with mesyl chloride in the presence of pyridine, and the resulting dimesyl derivatives were converted to allyl esters of the constituent acids by treatment with sodium iodide in anhydrous acetone at 100°C.
Abstract: A procedure has been developed for the quantitative estimation of monoglycerides in terms of their constituent fatty acids. The monoglyceride mixture is mesylated with mesyl chloride in the presence of pyridine, and the resulting dimesyl derivatives are converted to allyl esters of the constituent fatty acids by treatment with sodium iodide in anhydrous acetone at 100°C. The allyl esters are then analyzed quantitatively by gas-liquid partition chromatography at 240°C. on a column of Apiezon M—Celite. Both α- and β-monoglycerides are quantitatively converted to allyl esters by this procedure. β-Monoglycerides in a mixture of α- and β-isomers may be determined separately after removal of the α-isomers by oxidation with periodic acid. The analytical procedure is also applicable to monoglycerides in the presence of free fatty acids, diglycerides, and triglycerides.
TL;DR: In this article, six species of Malvaceae, representing four genera, were found to contain cis-12,13-epoxyoleic acid in amounts estimated at 1,5-7% of the total fatty acids.
Abstract: Seed oils of six species ofMalvaceae, representing four genera, were found to containcis-12,13-epoxyoleic acid in amounts estimated at 1,5–7% of the total fatty acids. Acetolysis of the oils gave the corresponding dihydroxyoleic acid, which was shown to be predominantly adextro-rotatory form ofthreo-12,13-dihydroxyoleic acid. It was obtained optically pure, and its structure was confirmed by orthodox methods. The hydrogenation product, (+)-threo-12,13-dihydroxystearic acid, was also obtained optically pure and characterized. The best yield of dihydroxyoleic acid was obtained from the seed oil ofMalope trifida.
TL;DR: Petroselinic acid of a grade which is suitable for most laboratory applications has been prepared by a single crystallization of the mixed fatty acids of parsley seed oil from 90% ethanol.
Abstract: Petroselinic acid of a grade which is suitable for most laboratory applications has been prepared by a single crystallization of the mixed fatty acids of parsley seed oil from 90% ethanol. A product of higher purity has been prepared from this acid by application of urea segregation techniques for the removal of saturated materials. No evidence of the presence of unsaturated fatty acids other than petroselinic acid was found in either of these samples when their ozonolysis products were examined chromatographically. On the basis of iodine values, assuming the absence of other unsaturated materials, the purities of the two preparations are 96.0 and 99.4%.
TL;DR: In this paper, the percentage of arachidonic and pentacnoic acids in lard by GLC was determined by using thermal conductivity detectors, which agreed well with known percentages in model mixtures and with analysis by the spectrophotometric method for fats and oils.
Abstract: 1.
Known mixtures of pure fatty acid methyl esters and a number of fats and oils as their methyl esters have been analyzed by conventional GLC with thermal conductivity detectors.
2.
Percentage of fatty acid distribution determined by GLC agreed well with known percentages in model mixtures and with analysis by the spectrophotometric method for fats and oils.
3.
Determination of very small amounts of arachidonic and pentacnoic acids in lard by GLC was not successful.
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TL;DR: A method has been devised for determining the relative esterifiability of the primary and secondary hydroxyl groups of glycerol and it is suggested that this method should be applicable to other polyols.
Abstract: A method has been devised for determining the relative esterifiability of the primary and secondary hydroxyl groups of glycerol Contrary to the theory previously advanced by Feuge and Bailey, the primary and secondary hydroxyls are not equally esterifiable The equilibrium constant favoring esterification of primary hydroxyl over secondary isca 23 at reaction temperature (200°C) and between 6 and 10 at room temperature Since the equilibrium constant is substantially different at room temperature from that at reaction temperature, monoglycerides as customarily prepared are not at equilibrium at room temperature and undergo intramolecular migration of acyl groups frombeta toalpha hydroxyl positions The rate of migration depends on the physical form of the ester and is accelerated by basic catalysts In the vicinity of room temperature intermolecular rearrangement occurs only over very prolonged periods The method of calculating relative esterifiability of primary and secondary hydroxyls should be applicable to other polyols
TL;DR: In this article, organic soil that had gradually accumulated on cotton garments and was unremovable by normal washing procedures was analyzed for free and combined fatty acids by gas-liquid chromatography.
Abstract: Organic soil that had gradually accumulated on cotton garments and was unremovable by normal washing procedures was analyzed for free and combined fatty acids by gas-liquid chromatography. The fatty acid composition of this material was similar to sebum and hair fat and was remarkably uniform although from several different sources and geographical locations. The predominant fatty acids were C15, C16, and C18 straight-chain acids. More than 30% of the total fatty acid was palmitic acid. The amount of oleic acid was considerably less than is reported for hair and skin fat. No linoleic acid or linolenic acid was detected. The small amount of unsaturated acids is probably the result of their oxidation to polymers and other oxidation products. The amount of free fatty acids was very small because they were converted to insoluble heavy metal soaps. Most of the combined fatty acids were present as esters,i.e., triglycerides.
TL;DR: A solvent system different from that used for glyceryl and ethylene glycol ester mixtures was developed and the esters of polyethylene glycols with average molecular weights of 300–600 were shown to give the same chromatogram.
Abstract: A procedure for the chromatographic separation and determination of the ester mixtures of glycerin, ethylene glycol, and polyethylene glycol is presented. The adsorbent is silea gel, and the mobile phase is a series of solvents with increasing polarity. A procedure for quantitative determination of small amounts of monoglyceride present in a glyceryl ester mixture is presented. A solvent system different from that used for glyceryl and ethylene glycol ester mixtures was developed for ester mixtures of polyethylene glycols. The esters of polyethylene glycols with average molecular weights of 300–600 were shown to give the same chromatogram.