Comparative rates of oxidation of isomeric linolenic acids and their esters

Myers, Jenny; Kass, J. P.; Burr, George O.

doi:10.1007/bf02545420

Cited by 21 publications

(3 citation statements)

References 11 publications

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“…Further support for the possible adverse effect of cis-trans isomerization is found in the oxidation rates of the conjugated trienoie acids (19). Table VII shows how the oxygen absorption of three different conjugated octadeeatrienoic acids varies with respect to differences in position and cis-trans isomerization.…”

Section: Mechanism Of Nickel Isomerizationmentioning

confidence: 87%

Isomerization and trans‐esterification

Cowan

1950

J Americ Oil Chem Soc

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Section: Mechanism Of Nickel Isomerizationmentioning

confidence: 87%

Isomerization and trans‐esterification

Cowan

1950

J Americ Oil Chem Soc

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“…was prepared according to Kass, Nichols, and Burr (12). The a-and /3-eleostearic acids were isolated from tung oil (18). Pseudoeleostearic acid was prepared by the method of Kass and Burr (lly S-Licanic acid was isolated from oiticica oil (5), and ricinoleic acid was prepared by the low-temperature crystallization of castor oil acids (4).…”

mentioning

confidence: 99%

A Monolayer Study of the Isomerism of Unsaturated and Oxy Fatty Acids.

Schneider¹,

Holman²,

Burr³

1949

J. Phys. Chem.

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Monomolecular films of fatty acids on water solutions have been studied extensively and have been found to show properties related to the molecular structure of the fatty acids (1). The force-area curves of monolayers indicate the apparent cross-sectional area of the molecules in the film, and their shapes differ one from the other dependent upon intermolecular forces, which in turn are an expression of the molecular structure. Studies of monolayers of some unsaturated fatty acids have been made (1, 3, 9, 16), but a systematic comparison of the monolayers of isomers of unsaturated fatty acids, including conjugated and nonconjugated polyunsaturated acids, has hitherto not been carried oui. Such a study of isomers of unsaturated acids could conceivably give more information as to the effects of isomerism upon the packing of molecules in a monolayer and, conversely, could perhaps offer evidence regarding the structure of tarty acids whose structure is not definitely known.Inasmuch as a group of oxy fatty acids were available for study, it .-eemed also of interest, as a basis for the study of the oxidation of unsaturated fatty acids in monolayers, that the force-area curves of these be investigated. Some of these substances also afford further opportunity for the study of the effect of isomerism upon monolayer characteristics. EXPERIMENTAL Monolayers were spread on Ay 100 sulfuric acid containing 0.12 per cent hydroquinone in a Langmuir hydrophil balance supplied by the Central Scientific Company. The films were spread from dilute solutions of the fatty acids in redistilled petroleum ether (b.p. 45°C.) except in the cases of /3-licanic acid, diketostearic acid, and rieinelaidic acid, for which redistilled c.p. thiophene-free benzene was used as solvent. The solutions were expelled onto the water surface from a calibrated 0.5-ml. syringe having a stationary back-stop. All experiments were run at room temperature, and with each substance tested, a sample of stearic acid was run as a standard. The limiting areas were corrected assuming that• of stearic acid to be 24.4 A.', as found by Nutting and Harkins (201 -The experimental data are taken from a thesis submitted to the Graduate School of the University of Minnesota by V. Lorraine Schneider in partial fulfillment of the requirements for the degree of Master of Science in 1946.

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“…Although the exact individual components of lard are not available, they may be represented, approximately, by methyl oleate, methyl stearate, and methyl linoteate. A number of workers have investigated the oxygen absorption of fat acids and esters (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), but no single investigation has included all the methyl esters of the fat acids of lard and mixtures of these methyl esters.…”

mentioning

confidence: 99%

Oxygen absorption of methyl esters of fat acids, and the effect of antioxidants

1945

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K NOWLEDGE concerning the oxidation of the individual components of lard as well as their mixtures should be of value in disclosing the course of the development of oxidative rancidity. Furthermore the behavior of antioxidants with each component may help to reveal the nature of their protective action with lard.Although the exact individual components of lard are not available, they may be represented, approximately, by methyl oleate, methyl stearate, and methyl linoteate. A number of workers have investigated the oxygen absorption of fat acids and esters (1-12), but no single investigation has included all the methyl esters of the fat acids of lard and mixtures of these methyl esters.The usefulness of the Barcroft-Warburg apparatus in the study of the autoxidation of fats has been demonstrated (13,14) and it was our purpose to apply this convenient method to the methyl esters of fat acids representing the components of lard. Accordingly methyl oleate, methyl stearate, methyl linoleate, the distilled methyl esters of lard, and various mixtures of the individual methyl esters were prepared, and their oxygen absorption at 100 ° C. was determined. In addition, for general comparative purposes, measurements of the oxygen absorption of methyl linolenate were included.A group of antioxidants was evaluated with methyl linoleate, methyl oleate, methyl stearate, and the distilled methyl esters of lard. The antioxidants were a-tocopherol, nordihydroguaiaretic acid (NDGA), propyl gallate, benzylhydroquinone, and synergistic combinations with citric acid, d-isoascorbyl palmitate, and lecithin.As might be expected, methyl linolenate, methyl linoleate, the distilled methyl esters of lard, methyl oleate, and methyl stearate absorbed oxygen und developed peroxides, at relative rates in the order named. Mixtures of substrates absorbed oxygen at a rate which could be approximately predicted from the rate of oxygen absorption of the individual components. The order of effectiveness of the antioxidants varied somewhat with the different substrates but in each case the combinations of nordihydroguaiaretic acid and of propyl gallate with citric acid were the most powerful antioxidants. Preparation of the SubstratesN ETHYL oleate was prepared from the methyl esters of lard by a series of low-temperature fractional crystallizations and fractional vacuum distillations (15). The final product had an iodine nnmber of 85.5 (Wijs).Methyl stearate was prepared from hydrogenated soybean oil fat acids by esterification with methyl * One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, United States Department of Agriculture.alcohol; sulfuric acid was used as a catalyst. After fractional vacuum distillation and recrystallization the methyl stearate had a saponification equivalent of 300.4; a melting point of 39.0-39.4 ° ; and an iodine number of zero (Wijs).Methyl linoleate was prepared from the unsaturated fat acids of cottonseed oil (16) by the method of Rollett (17). Methyl lin...

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Comparative rates of oxidation of isomeric linolenic acids and their esters

Cited by 21 publications

References 11 publications

Isomerization and trans‐esterification

Isomerization and trans‐esterification

A Monolayer Study of the Isomerism of Unsaturated and Oxy Fatty Acids.

Oxygen absorption of methyl esters of fat acids, and the effect of antioxidants

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