Oxidation Of Methyl Linoleate Research Articles

L-proline Interaction with Methyl Linoleate Oxidation Products Formation in Dry System and at Temperatures: For Understanding in Low-Moisture Foods

Dry and low-moisture foods could experience a significant loss in nutritional value due to the process of methyl linoleate oxidation. L-proline could interact with lipid oxidation products, potentially modifying their formation and reaction path. However, there was a lack of research on the interaction between L-proline and methyl linoleate oxidation products in dry and low-moisture food matrices, which was a concern given the potential impact on food safety and nutrition. To address this knowledge gap, a study investigated the interaction between L-proline and the oxidation products of methyl linoleate in a dry system. The study examined the formation of methyl linoleate oxidation products such as conjugated dienes, hydroperoxide, and hexanal in the absence and presence of varying moles of L-proline at different temperatures. The formation of conjugated diene, hydroperoxide, and hexanal was analyzed using UV spectrometer analysis, xylenol orange, and DNPH derivatization HPLC-UV analysis. The results showed that adding proline to methyl linoleate samples stabilized conjugated diene and decreased hydroperoxide and hexanal levels as temperature increased, compared to the control sample. This suggests that L-proline effectively interacted with methyl linoleate oxidation products and altered their formation and oxidation path in the dry system. Overall, this study provided a basis for significantly enhancing understanding of the reactions between L-proline and methyl linoleate oxidation products in dry and low-moisture foods, offered practical implications for the food industry, and paved the way for future research.

Kinetics and mechanism of methyl linoleate oxidation in cetyltrimethylammonium bromide micelles

Kinetics and mechanism of methyl linoleate oxidation in cetyltrimethylammonium bromide micelles

Oxidation of Methyl Linoleate in Triton X‐100 Micelles Initiated by Lipid‐soluble Initiator 2,2′‐Azobis (2,4‐dimethylvaleronitrile)

AbstractThis article discusses the oxidation of methyl linoleate in micelles, initiated by the lipid‐soluble initiator 2,2′‐azobis (2,4‐dimethylvaleronitrile) (AMVN). It was shown that the rate constant (ki) is initiated in micelles for AMVN significantly lower than the known rate constant of initiation in true solutions. This can be explained by the reduced probability of AMVN radicals leaving the cage and an increase in the rate of chain termination between initiator radicals under conditions of low oxygen content. This conclusion was confirmed by quantum chemical calculations. Surprisingly, when determining the AMVN initiation rate constant for the consumption of nitroxyl radicals (>NO⋅), the ki depends on the concentration >NO⋅, this is due to the dependence of the probability of the nitroxyl radical and initiator radicals in micelles meeting on their concentration. Upon initiation of AMVN, no hydroperoxyl radical is expelled.

Kinetic modeling of the reversal of antioxidant potency of α-, β-, γ- and δ-tocopherols in methyl linoleate peroxidation

Extended, chemically detailed kinetic models at the molecular basis are constructed to identify the reactions involved in the reversal of the antioxidant action of α-, β-, γ- and δ-tocopherols during methyl linoleate oxidation. The reaction mechanisms were numerically simulated and subjected to analysis to quantify the significance of individual chemical steps by the value-based method. Results of the obtained kinetic models agreed well with the experimental data. The significant individual reactions contributing to the observed antioxidant and pro-oxidant behavior of the different tocopherols were identified. It is revealed that the reverse order of antioxidant potency and a complex nonlinear dependency of the antioxidant potency of tocopherols with the increase in their concentration are due to the increasing contribution of pro-oxidant relative to the antioxidant reactions. Once the approach presented here can be applied to more complex systems, engineered optimization of antioxidant protection strategies may be reached.

Molecular dynamics simulation and experimental research on the oxidation reaction of methyl linoleate at low oxygen and high temperature

The pyrolysis and low-oxygen high-temperature oxidation process of methyl linoleate containing two unsaturated double bonds were analyzed by kinetic analysis, density functional theory calculation and ReaxFF-MD considering it as a substitute for biodiesel. The combined system of TG-FTIR-MS was used to analyze the escape characteristics of multi-component gas product during the pyrolysis as well as high-temperature oxidation of methyl linoleate under low-oxygen. The ReaxFF-MD molecular dynamics method was used to analyze the effect of initial reaction path of the thermal decomposition of methyl linoleate and the oxygen content on the oxidation reaction products. The results show that the pyrolysis of methyl linoleate has reaction activation energy of 58.2 kJ/mol, while, for the high-temperature oxidation process under low oxygen, it is 58.79 kJ/mol. The main gaseous products are CO2, CH4, CO/C2H4, H2O and products containing C–H, C–O, CO and other functional groups. Through DFT calculations and ReaxFF-MD, we found that breaking of C–O bond leading to the formation of smaller CH3 radical and decarboxylation to form CO2 constitute the initiation mechanism for the pyrolysis of methyl linoleate pyrolysis and high-temperature oxidation in presence of low oxygen. The double bond of methyl linoleate is prone to generate C7H10 intermediates with higher carbon content during the pyrolysis process. At the same time, through simulation, we found that oxygen and fuel are mixed as soon as possible at the beginning of the combustion of methyl linoleate which helps to reduce the production of C2 products from the pyrolysis of methyl linoleate.

Study on transition metal ion Fe3+ catalyzed biodiesel oxidation and inhibition mechanism

Methyl linoleate is used as an alternative component of biodiesel. The catalytic oxidation of biodiesel is studied in the presence of iron acetate using methyl linoleate as the alternative component. The composition of the products obtained from the oxidation process of methyl linoleate is analyzed by GC–MS and liquid phase microextraction. Density functional theory is used to calculate the electronic effects of the related reactants and products and the related catalytic oxidation reaction paths are derived. The results show that during the process of catalytic oxidation of methyl linoleate in biodiesel, mainly the catalytic cracking reaction of C–H and C–C bonds and Fenton-like reaction occur. The combination of two antioxidants, TEPA and [MI][C6H2(OH)3COO], can effectively inhibit the catalytic oxidation of Cu2+ and Fe3+ and interrupt the chain reaction of the oxidation process. The negative value of the electrostatic potential of ferric acetate is relatively large, it is obviously alkaline, and has a certain ability to bind with H. The irregular structure of the iron acetate unit cell makes the O–Fe bond in the molecule easy to break, which is beneficial for the catalytic oxidation process.

Kinetic model of polyunsaturated fatty acids oxidation in micelles

A kinetic model of polyunsaturated fatty acids (PUFAs) radical chain oxidation in micelles is presented, taking into account the diffusion of active intermediates between aqueous and organic phases, and its effect on the detailed mechanism of the process. The model made it possible to indirectly involve the structural changes of micelles and their kinetic characteristics by varying the actual values of the reactions rate constants. The modeling results are in good agreement with experimental data for the oxidation of methyl linoleate and linoleic acid.

Study on the mechanism of auto-oxidation of Jatropha biodiesel and the oxidative cleavage of C[sbnd]C bond

Jatropha biodiesel was obtained according to the continuous preparation process which included vapor esterification - transesterification - methanol steam distillation. Accelerated oxidation of small Jatropha biodiesel was obtained by the Rancimat method. GC–MS and liquid phase micro-extraction were used to study and analyze the components in the oxidation process of Jatropha curcas biodiesel. The electronic effects of the related reactants and products were calculated by density functional theory, followed by the deduction of the related chemical reaction paths. Experimental investigation shows that methyl linoleate is the main factor affecting the oxidation stability of the Jatropha biodiesel. The main volatile products at the initial stages of the oxidation of methyl linoleate are hexanal, methyl octanoate, styrene, and 2-heptenal. The cis/trans-3-octyl-oxiranyl octanoic acid methyl ester (18.03% yield) is produced by the reaction of peroxy acid and methyl oleate during the oxidation of methyl oleate. The hydrogen extraction reaction is difficult to occur, and the oxidation reaction energy barrier is relatively high due to the relatively large bond energy of the CH bond in the methyl stearate molecule. In this manuscript, the auto-oxidation mechanism of the biodiesel fatty acid methyl esters at the initial stage of oxidation, the path of oxidative cleavage of the CC bond of Jatropha biodiesel and the formation process of ethylene oxide structure are obtained through DFT calculation and analysis of the oxidation products.

Effect of Cysteine on the Antioxidant Activity of Nitroxyl Radicals during the Oxidation of Methyl Linoleate in Micelles

Using the model of methyl linoleate (LH) oxidation in micelles, the effect of cysteine on the antioxidant activity of nitroxyl radicals (NR) in micelles is studied. It is found that cysteine enhances the antioxidant effect of NR with a low reduction potential of the oxoammonium cation + nitroxyl radical pair, which is due to the formation of the corresponding hydroxylamines (HA).

Features of Methyl Linoleate Oxidation in Triton X-100 Micellar Buffer Solutions

Features of Methyl Linoleate Oxidation in Triton X-100 Micellar Buffer Solutions

Quantum chemical evaluation of the role of $${{{\text{HO}}_{2}}^{ \cdot }}$$ radicals in the kinetics of the methyl linoleate oxidation in micelles

The process of lipid peroxidation (LPO) plays an extremely important role in the human body due to the fact that its uncontrolled development can lead to oxidative stress and a number of serious diseases. The traditional approach to the analysis of the mechanism and kinetics of LPO is based on the well-known ideas that emerged from the study of radical-chain oxidation of hydrocarbons in a homogeneous medium. However, the distinctive feature of LPO is that this process is heterogeneous and the processes of diffusion of active intermediates between the aqueous and hydrocarbon phases should play a significant role in it. In the present work, an attempt has been made to theoretically estimate the contribution of these processes to the oxidation kinetics of model substances used in practice in the study of LPO. In the course of the calculations, a quantum chemical and kinetic analysis of the role of hydroperoxyl radical in the radical-chain mechanism of oxidation of methyl linoleate in micelles was carried out. The molecular dynamics method shows the important role of changing the dynamic rigidity of a hydrocarbon fragment of a chain during the formation of a peroxyl radical and hydroperoxyl group during the oxidation of a substrate in a heterogeneous medium. Quantum chemical calculations of the thermodynamics of reactions involving $${{{\text{HO}}_{2}}^{ \cdot }}$$ radicals and the effects of their solvation made it possible to estimate the kinetic constants of the reaction rates. Using kinetic modeling, their relative contribution to the oxidation kinetics was revealed. In this case, it is possible to explain a number of anomalies associated with the oxidation of polyunsaturated fatty acids and their esters in micelles compared with their oxidation in a homogeneous hydrocarbon medium.

New Insights on the Oxidation of Unsaturated Fatty Acid Methyl Esters Catalyzed by Niobium(V) Oxide. A Study of the Catalyst Surface Reactivity

The catalytic properties of niobium(V) oxide (Nb2O5-CBMN) of different grades: amorphous, optical and ultra-pure, untreated or heat-treated at 400, 500, 700 and 900 °C were studied, before and after interaction with H2O2, by in situ Raman, FTIR-ATR and diffuse reflectance UV-Visible spectroscopy. The presence of different reaction sites for NbO7 and NbO8 type systems, which are directly related to surface defects present in different states of crystallization, were fully characterized. The reactivity of different catalysts obtained from niobium(V) oxide was investigated, using the oxidation of methyl linoleate in the presence of hydrogen peroxide as probe reaction. The reaction was followed by GC-MS, as well as by 1H and 13C NMR spectrometry and the dominant product was 9-oxo-nonanoic acid methyl ester. A reaction mechanism related to an auto-oxidation process must be occurring, leading initially to the formation of hydroperoxides, which decompose rapidly via Hock-type rearrangement, leading to the formation of aldehydes.

Superoxide radicals in the kinetics of nitroxide-inhibited oxidation of methyl linoleate in micelles

The kinetics of the oxidation of methyl linoleate in micelles inhibited by stable nitroxides under the conditions of initiation by superoxide radicals was studied. Multiple breakdown of the oxidation chains was observed in this process. The antioxidant activity of nitroxides increased when the reduction potential of the oxoammonium cation/nitroxide pair decreased and their lipophilicity increased.

Effect of superoxide dismutase on the oxidation of methyl linoleate in micelles inhibited by nitroxyl radicals

The kinetics of oxidation of methyl linoleate in micelles inhibited by stable nitroxyl radicals in the presence of superoxide dismutase was studied. In the presence of superoxide dismutase, nitroxyl radicals decrease the rate of oxidation to a lower extent and the process is characterized by lower inhibition coefficients. The results obtained demonstrate an important role of hydroperoxide radical in the mechanism of nitroxyl radical regeneration during the oxidation of methyl linoleate in micelles.

Effect of microheterogeneity on the kinetics of oxidation of methyl linoleate in micelles

The kinetic results of the radical chain oxidation of methyl linoleate (LH) in micelles were given. The oxidation rate depends on the average number of substrate molecules in the micelle and is almost independent of the micelle concentration under the given conditions. The chain propagation and termination were assumed to predominantly occur inside the micelle. Possible reasons for linear chain termination during the oxidation of polyunsaturated fatty esters in microheterogeneous systems were discussed.

Five-membered cyclic nitroxyl radicals as inhibitors of the oxidation of methyl linoleate in micelles

The kinetics of methyl linoleate oxidation in micelles inhibited by five-membered cyclic nitroxyl radicals and the corresponding hydroxylamines was studied. The partial regeneration of nitroxyl radicals in this process was found. The activity of the studied inhibitors increases with an increase in their lipophilicity.

Stable nitroxyl radicals and hydroxylamines as inhibitors of methyl linoleate oxidation in micelles

The kinetics of methyl linoleate oxidation in micelles inhibited by nitroxyl radicals and hydroxylamines was studied. The regeneration of nitroxyl radicals in this process was found. The activity of the studied inhibitors increases with increasing their lipophilicity. This effect was explained by increasing the distribution coefficient of the antioxidants in a micelles–water system. The reaction of nitroxyl radicals with the hydroperoxide radical formed upon the oxidation of methyl linoleate in micelles is proposed to be the key reaction in nitroxyl radical regeneration.

Determination of Oxidation of Methyl Ricinoleates

AbstractRicinoleate esters have desirable properties as biolubricants, but their oxidative stability has been questioned. To systematically study the stability of ricinoleate ester and its derivative, methyl esters of castor oil were prepared and methyl ricinoleate was isolated by solvent partitioning. Methyl 12‐acetyl ricinoleate was synthesized from the methyl ricinoleate by interesterification with excess methyl acetate and was then purified by solvent partitioning. The rates of oxidation of methyl linoleate, methyl oleate and the two ricinoleate esters were measured by oxidation of lipid dispersed on glass beads under three temperatures (40–80 °C). The relative amounts of the unoxidized methyl esters were determined periodically by gas chromatography, and the peroxide value of the oils was also determined. The oxidation rates were determined as the peroxide value increase rate, as well as the ester disappearance rate, and the stability of the various esters was compared. Overall, methyl ricinoleate was much more oxidatively stable than methyl oleate at mildly elevated temperatures, and the acetylation of the hydroxyl group on the 12th carbon decreased the stability.

Effect of mercaptoethanol on the hydrocarbon oxidation and cis—trans-isomerization of unsaturated lipids

The kinetics of the oxidation of ethylbenzene, limonene, and methyl linoleate containing mercaptoethanol additives were studied, as well as cis—trans-isomerization of the double bonds in methyl linoleate. Mercaptoethanol (RSH) additives were found to accelerate the oxidation of hydrocarbons and methyl linoleate due to the reaction of RSH with hydroperoxides (primary oxidation products) resulting in a low yield of free radicals. The cis—trans-isomerization catalyzed by thiyl radicals produced in the exchange radical reactions with RSH decelerates in the presence of oxygen.

Kinetic study and simulation of methyl linoleate oxidation in micelles

The results of experiments and computer simulations on the radical-chain oxidation of methyl linoleate in micelles are reported. The reaction rate constants included in the developed mathematical model are estimated. The ratio of the rates of first-order and bimolecular chain termination is examined. It is demonstrated that the rate constant of bimolecular chain termination in micelles is lower than that in the homogeneous phase.