Oil Oxidation Products Research Articles

EFFECT OF OXIDATION PRODUCTS AND OTHER PRECURSORS ON THE CONTENT OF 3-MCPD ESTERS AND GLYCIDOL ESTERS IN DEODORISED SUNFLOWER OIL

This paper investigates the effect of precursors on the formation of 3-MCPD esters (3-MCPD-E) and glycidol esters (GE) and discusses ways to reduce the concentration of these toxic esters in deodorised oils. As the content of oxidation products in sunflower oil increases, the amount of MCPD esters formed after deodorisation increases too: from 560 μg/kg (for oil with the peroxide value 1.06 mmol 1/2О/kg and the anisidine value 0.55) to 1290 μg/kg (for oil with PV=6.73 mmol 1/2O/kg and PAV=10.38). Thus, peroxides and aldehydes should be classified as the initiators of the formation of 3-MCPD-E. Accordingly, a way to reduce toxic 3-MCPD-E in deodorised oils is by preventing the formation of oxidation products during the extraction and processing of oils, or by reducing the content of oxidation products in oils before deodorisation. On the contrary, there is no correlation between the content of oxidation products and the amount of glycidol esters in deodorised oil. No relationship has been found between the content of natural antioxidants of oils, tocopherols, and the amount of 3-MCPD-E and GE. Increasing the pH of oils leads to a higher content of 3-MCPD-E resulting from deodorisation. As the number of acid groups increases, the amount of 3-MCPD-E increases too. Conversely, with bigger amounts of acid introduced into the oil, no additional quantities of glycidol esters are formed in the course of deodorisation.

Molecular composition of low-temperature oxidation products in a simulated crude oil In-situ combustion

In-situ combustion (ISC) is a thermal enhanced oil recovery process in which energy is generated by the combustion of a portion of the oil within the reservoir. Low temperature oxidation (LTO) is one of the dominant mechanisms controlling fuel availability in ISC and affects the physical properties of the crude oil, thus the characterization of the crude oil and its LTO products are essential for a better understanding of the ISC process. In this study, a thermal oxidation experiment of a heavy crude oil was carried out to investigate the molecular changes associated to coke formation during ISC. More than half of the component was depleted by combustion or thermal pyrolyzed out, leaving a coke-like solid in the reactor with a yield of a quarter by weight of the crude oil. More than 90% of the coke-like solid is toluene soluble. Condensate oil expelled from the reactor was collected with a yield of about 15 wt% of the crude oil. Small-molecule oxidation products, such as ketones, fatty acids, phenolic compounds were identified in the condensate by GC–MS. High-resolution mass spectrometry results showed that the molecular composition of oxygen- and sulfur-containing compounds changed largely, with the generation of highly oxygenated compounds and sulfoxides. A substantial portion of large-molecule hydrocarbons were survived and enriched in the residue. The main components in the toluene insoluble substance, namely oxidation coke, are methanol soluble and composed of highly oxygenated compounds. The results indicate that oxidation and thermal cracking are both the important reaction in the simulated ISC, the molecular composition is instructive for the understanding of pyrolysis and oxidation behavior of coke formation from the crude oil.

Comparative 1H NMR-Based Chemometric Evaluations of the Time-Dependent Generation of Aldehydic Lipid Oxidation Products in Culinary Oils Exposed to Laboratory-Simulated Shallow Frying Episodes: Differential Patterns Observed for Omega-3 Fatty Acid-Containing Soybean Oils.

Soybean oil is the second most exported oil from the United States and South America, and is widely marketed as a cooking oil product containing numerous health benefits for human consumers. However, culinary oils with high polyunsaturated fatty acid (PUFA) contents, are known to produce high quantities of lipid oxidation products (LOPs), including toxic aldehydes upon exposure to high-temperature frying episodes. Previous studies have demonstrated causal links between aldehyde ingestion and inhalation with deleterious health perturbations, including mutagenic and carcinogenic effects, along with cardiovascular and teratogenic actions. In this study, aldehydic LOPs were detected and quantified in commercially available samples of soybean, avocado, corn and extra-virgin olive oil products before and after their exposure to laboratory-simulated laboratory frying episodes (LSSFEs) using high-resolution 1H nuclear magnetic resonance (NMR) analysis. Results acquired demonstrated that PUFA-rich soybean and corn oils gave rise to the highest concentrations of oil aldehydes from the thermo-oxidation of unsaturated fatty acids, whereas monounsaturated fatty acid (MUFA)-laden avocado and olive oils were much more resistant to this peroxidation process, as expected. Multivariate chemometrics analyses provided evidence that an orthogonal component pattern of aldehydic LOPs featuring low-molecular-mass n-alkanals such as propanal, and 4-oxo-alkanals, arises from thermo-oxidation of the ω-3 fatty acid (FA) linolenic acid (present in soybean oils at levels of ca. 7% (w/w)), was able to at least partially distinguish this oil from corresponding samples of thermally-stressed corn oil. Despite having a similar total PUFA level, corn oil has only a negligible ω-3 FA content, and therefore generated significantly lower levels of these two aldehyde classes. In view of the adverse health effects associated with dietary LOP ingestion, alternative methodologies for the incorporation of soybean oils within high-temperature frying practices are proposed.

DSC study on combustion behavior of tahe heavy oil and its low temperature oxidation products

In this study, the combustion behaviors of heavy oil and low temperature oxidation products were analyzed by differential scanning calorimetry (DSC) technique. The results elucidated that the coke formed after static oxidation showed the highest heat release (24.03 kJ/g), which was a positive signal for the in-situ combustion (ISC) process of Tahe heavy oil. The most abundant asphaltenes in heavy oil and residue contributed more fuel for high temperature oxidation (HTO), resulting the two samples to exhibit intense HTO reactions. In summary, activation energies of the samples in the low temperature oxidation (LTO) were higher than that in HTO region.

The Role of Polydimethylsiloxane in Suppressing the Evolution of Lipid Oxidation Products in Thermo-Oxidised Sunflower Oil: Influence of Stirring Processes.

Suppressing the evolution of lipid oxidation products (LOPs) in commercially available culinary oils is considered to represent a valuable health-promoting incentive since these agents have cytotoxic and genotoxic properties and have been implicated in the pathogenesis of several chronic disease states. One agent used to suppress LOPs formation is polydimethylsiloxane (PDMS). In this study, proton nuclear magnetic resonance (1H NMR) analysis was employed to evaluating the influence of increasing PDMS concentrations (6.25 × 10−7, 1.0 × 10−5, 0.025, 0.05, 0.1, 0.5, 1.0, 5.0, and 10.0 ppm) in either stirred or unstirred refined sunflower oil exposed to thermal stressing episodes continuously at 180°C for 300 min with no oil replenishment. Results acquired showed that the extent of blockage of LOPs generation was correlated with increasing concentrations of PDMS. The minimal level of added PDMS required to provide a statistically significant protective role for both stirred and unstirred culinary oils when exposed to high frying temperatures was only 6.25 × 10−7 ppm. Furthermore, stirring at 250 rpm was experimentally determined to reduce the functional role PDMS. This is vital in a real world setting since the boiling process of frying may ultimately reduce the LOPs suppression activity of PDMS.

Bleaching with the Mixed Adsorbents of Activated Earth and Activated Alumina to Reduce Color and Oxidation Products of Anchovy Oil

Bleaching with the Mixed Adsorbents of Activated Earth and Activated Alumina to Reduce Color and Oxidation Products of Anchovy Oil

In-situ assessment of olive oil adulteration with soybean oil based on thermogravimetric-gas chromatography/mass spectrometry combined with chemometrics

The feasibility of thermogravimetric-gas chromatography/mass spectrometry (TGA-GC/MS) combined with chemometrics for qualitative and quantitative determination of adulteration of olive oil with soybean oil was described. Discriminative separation between the two groups of oil samples could be seen from the principal component analysis (PCA). For quantitative evaluation, olive oils and mixtures with soybean oil at levels of 25%, 50% and 75% were analyzed. The least squares exponential fitting was conducted on the ratio of peak area of typical characteristic volatile oxidation products of olive oil to that of soybean oil. Satisfactory results (R2 > 0.99) were obtained with 1-heptene/1-octen-3-ol, 1-octene/1-octen-3-ol, trans-2-decenal/1-octen-3-ol and 2-undecenal/1-octen-3-ol. To the best of our knowledge, this is the first report on the application of TGA-GC/MS for olive oil adulteration study. It has to be highlighted that the new proposed analytical method is non-destructive and avoids the use of organic solvent.

Effectiveness of the Natural Antioxidant 2,4,4'-Trihydroxychalcone on the Oxidation of Sunflower Oil during Storage.

This study aimed to investigate the effectiveness of 2,4,4′-trihydroxychalcone as a natural antioxidant on the oxidation of sunflower oil during an 88-day storage period and to compare its strength with the synthetic antioxidant butylated hydroxytoluene (BHT). Seven groups of the sunflower oil samples were prepared: pure oil (control), oil treated with different concentrations (100, 500, and 1000 ppm) of 2,4,4′-trihydroxychalcone, and oil treated with different concentrations (100, 500, and 1000 ppm) of BHT. Specific parameters, namely, the peroxide value (PV), acid value (AV), p-anisidine value (p-AnV), thiobarbituric acid reactive substance (TBARS) value and total oxidation (TOTOX) value were used to assess the extent of the deterioration of the oil by estimating the primary and secondary oxidation products. The results showed that 2,4,4′-trihydroxychalcone effectively decreased the production of the primary and secondary oxidation products of sunflower oil during storage, as indicated by reductions in the PVs, AVs, p-AnVs, TBARS values and TOTOX values of the sunflower oil. When compared to BHT, 2,4,4′-trihydroxychalcone showed either a similar or stronger effect in inhibiting the primary and secondary oxidation products. These findings suggest that, 2,4,4′-trihydroxychalcone is a suitable natural alternative to synthetic antioxidants to improve the oxidative stability of sunflower oil.

Release Kinetics Studies of Early-Stage Volatile Secondary Oxidation Products of Rapeseed Oil Emitted during the Deep-Frying Process.

The research concerns the use of proton transfer reaction mass spectrometer to track real-time emissions of volatile secondary oxidation products released from rapeseed oil as a result of deep-frying of potato cubes. Therefore, it was possible to observe a sudden increase of volatile organic compound (VOC) emissions caused by immersion of the food, accompanied by a sudden release of steam from a potato cube and a decrease of the oil temperature by more than 20 °C. It was possible to identify and monitor the emission of major secondary oxidation products such as saturated and unsaturated aldehydes, namely acrolein, pentanal, 2-hexenal, hexanal, 2-nonenal and 2-decenal. Each of them has an individual release characteristic. Moreover, the impact of different initial frying temperatures on release kinetics was investigated. Subsequently, it was possible to approximate the cumulative emission by a second-degree polynomial (R2 ≥ 0.994). Using the proposed solution made it possible for the first time to observe the impact of the immersion of food in vegetable oil on the early emission of thermal degradation products oil.

Antioxidant Activity of Osage Orange Extract in Soybean Oil and Fish Oil during Storage

AbstractThe food industry is seeking natural antioxidants for edible oils that have comparable activity to synthetic counterparts. In this study, Osage orange extract (OOE) rich in osajin (42.9%) and pomiferin (30.0%) was obtained after hexane extraction of the fruit, and its antioxidant activity was examined in stripped soybean oil (SBO) and fish oil (FO), in which antioxidants and polar compounds were removed. The antioxidant activity of OOE was compared with commercial natural antioxidants (i.e., rosemary extract and mixed tocopherols) and a synthetic antioxidant, butylated hydroxytoluene (BHT), during storage at 25 and 40 °C. The 0.1% OOE had stronger antioxidant activity than 0.1% rosemary extract and 0.1% mixed tocopherols in both oils at 25 and 40 °C. Its activity was similar to 0.02% BHT in SBO and was similar or slightly stronger than 0.02% BHT in FO. When OOE was studied at 0.05, 0.1, and 0.2%, there was a weak dose–response in SBO but a stronger dose–response in FO. Headspace volatile analysis using solid phase micro‐extraction (SPME) combined with GC–MS indicated that 0.1% OOE was very effective in preventing the formation of volatile oxidation products in both oils. Although it should be further tested for safety before the actual use, this study shows that OOE can be developed as an antioxidant for edible oils.

Thermal-Oxidation Stability of Soybean Germ Phytosterols in Different Lipid Matrixes.

The stability of soybean germ phytosterols (SGPs) in different lipid matrixes, including soybean germ oil, olive oil, and lard, was studied at 120, 150, and 180 °C. Results on the loss rate demonstrated that SGPs were most stable in olive oil, followed by soybean germ oil, and lard in a decreasing order. It is most likely that unsaturated fatty acids could oxidize first, compete with consumption of oxygen, and then spare phytosterols from oxidation. The oxidation products of SGPS in non-oil and oil systems were also quantified. The results demonstrated that at relatively lower temperatures (120 and 150 °C), SGPs’ oxidation products were produced the most in the non-oil system, followed by lard, soybean germ oil, and olive oil. This was consistent with the loss rate pattern of SGPs. At a relatively higher temperature of 180 °C, the formation of SGPs’ oxidation products in soybean germ oil was quantitatively the same as that in lard, implying that the temperature became a dominative factor rather than the content of unsaturated fatty acids of lipid matrixes in the oxidation of SGPs.

Fluorescence and UV-VIS Spectroscopy to Determine the Quality Changes of Rapeseed Oil Fortified with New Antioxidant After Storage Under Various Conditions

This work focused on the application of synchronous fluorescence (SF) spectroscopy, excitation-emission matrix (EEM) fluorescence spectroscopy and modified UV-VIS methods for characterization of oxidative status and antioxidant activity (AA) of refined rapeseed oils fortified with the novel antioxidant octyl sinapate (OSA) at two concentrations and butylated hydroxyanisole (BHA) stored in different types of packages under various storage conditions. Quality parameters such as amounts of the primary and secondary oxidation products in rapeseed oils increased after storage under various conditions, whereas the AA of oils decreased. However, OSA strongly inhibited the generation of primary oxidation products in oils exposed to light. The AA of rapeseed oil with 0.5% of OSA packed in transparent glass after exposure to light was 6 times higher than the AA of non-supplemented oil. Moreover, the intensities of bands attributed to tocopherols and phenolic compounds decreased during storage depending on the storage conditions, but characteristic peaks for generation of oxidation products appeared. Interestingly, the fluorescence spectra of oil fortified with 0.5% of OSA contained the information of a new fluorescent product. Moreover, the potential usefulness of EEM to study the effect of antioxidants on degradation of stored rapeseed oils was demonstrated. Fluorescence spectroscopy can be used to investigate the oxidation state of rapeseed oils packed in various containers during storage at different conditions. The addition of the lipophilic antioxidant to rapeseed oil effectively delayed the oxidation process and significantly increased its AA.

Production of binding materials based on high-viscosity oils and natural bitumens

Due to the growing market demand for road bitumen, there is a need to increase the rate of its production. Among the promising technologies currently available, the oxidation of heavy hydrocarbon raw materials with air oxygen is the most optimal technology for producing bituminous binders. In turn, substandard oil reserves are suitable raw materials for this process. Thus, the study of the regularities between the composition of the oxidation products of ultra-viscous oil and the physicochemical properties of the oxidation conditions will contribute to the development of the binding materials production technology.

Changes in markers of lipid oxidation and thermal treatment in feed-grade fats and oils.

Oxidized feed lipids have been shown to have detrimental effects on food animal growth and metabolism. The present study aimed to measure classes of lipid oxidation products (LOP) in feed-grade oils at temperatures representing production and storage conditions. There were significant oil type × time interactions in the accumulation of primary and secondary LOP. At 22.5 °C, peroxide value (PV), a marker for the primary phase of lipid oxidation, increased most in fish oil (FO), followed by tallow (TL), soybean oil (SO), linseed oil (LO) and modified algae oil (MAO), whereas palm oil (PO) showed no appreciable increase in PV. Secondary LOP, such as p-anisidine value, hexanal, 2,4,-decadienal, polymerized triacylglycerols and total polar compounds, increased only in FO. At 45 °C, FO and SO produced both primary and secondary LOP, whereas MAO, PO and TL had slower rates of PV increase and no secondary LOP. At 90 °C and 180 °C, all oils except for FO accumulated both primary and secondary LOP. Higher polyunsaturated fatty acid:saturated fatty acid oils and higher temperatures produced greater quantities of primary and secondary LOP. However, unrefined TL was more prone to oxidation at 22.5 °C than predicted, whereas LO was more stable than predicted, indicating that pro-oxidant and antioxidant compounds can markedly influence the rate of oxidation. Measuring both primary and secondary LOP will provide better information about the oxidative status of feed oils and provide better information about which classes of LOP are responsible for detrimental health effects in animals. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.

Effect of Punicalagin as natural antioxidant on the oxidative stability of Canola oil during storage

The present study intends to determine the effect of punicalagin as natural antioxidant on stabilising canola oil during 90 days storage and also to compare its strength with the synthetic antioxidant Butylated hydroxytoluene (BHT). Canola oil samples were categorized into three groups; pure oil (control), oil with Punicalagin and oil with BHT. Peroxide value (PV) and free fatty acid (FFA) were used to estimate the primary products of oil oxidation while Thiobarbituric Acid Reactive Substances (TBARS) and P-Anisidine values (PAV) were used to estimate the secondary products. Finally, total oxidation index was calculated to evaluate the overall oxidation of oil samples. The results showed that PV, FFA, PAV and TOTOX were significantly increased in all canola oil samples with increased in storage time. In contrast, The TBARS values continued to increase from the starting storage period until 60 days and then decreased significantly until the end of the storage period. Punicalagin effectively reduces the production of the first and second oxidation products of canola oil during storage as indicated by the reduction in the PV, FFA, PAV and TOTOX of canola oil. When compared to BHT, punicalagin showed similar effect in inhibiting primary oxidation products whereas BHT showed stronger effect in reducing the secondary oxidation products. In conclusion, punicalagin can be used as a suitable replacement for chemically synthetic antioxidants on stabilising canola oil.

Estimation of the Oxidative Deterioration of Turbine Oil Using Membrane Patch Color

Lubricating oils degrade into two main products: oxidation products and solid particles. Oxidation products, called varnish, of turbine oils for power generation have become a particularly serious problem in recent years. The first step in determining the potential to produce varnish is to determine the remaining life of the antioxidant in the oil, but even though turbine oil may have antioxidants of sufficient longevity, varnish problems still occur frequently. Accordingly, to prevent varnish, it is necessary to diagnose oil oxidation products. Thus, the authors have developed a diagnostic method using membrane patch color, but the relationship between membrane patch color and the remaining life of turbine oils has yet to be clarified. This paper investigates a new method for estimating the oxidative degradation of turbine oils that uses membrane patch color and the dry turbine oxidation stability test (dry TOST) based on oxidation products and the remaining life of the turbine oils. Sample oils were prepared and degraded by oxidation in the laboratory using a dry TOST apparatus, and the membrane patch color was measured using a colorimetric patch analyzer (CPA). The relationship between membrane patch color and the rotating pressure vessel oxidation test (RPVOT) residual rate was then investigated. The results show that the new estimation method using the CPA and dry TOST is able to monitor the decrease of the RPVOT residual rate from the early stages of oxidative deterioration.

Development of diagnostics method of electricalinsulating liquid of transformer equipment

The work is to research the dielectric characteristics of vegetable-based oil during cyclic temperature aging and to determine the parameters necessary for monitoring the state of the oil, and to develop a method for diagnosing an insulating liquid. The research technique included measuring the dielectric constant of the oil and the tangent of dielectric loss for oil that underwent cyclic temperature oxidation. Thermal oxidation consisted in cyclic heating and natural cooling of the sample during the day without exposure to light. This was done to simulate changes of the temperature in the tank of the power transformer with a changing load schedule during the day. For comparison, the dielectric constant of the base sunflower oil was measured, which was stored in a glass container at room temperature without exposure to light. The results showed that the dielectric constant of vegetable-based oil increases linearly in the oxidation process. The increase in permittivity is associated with an increase in the number of polar molecules as a result of the formation of secondary oxidation products. Under the influence of temperature, the chemical composition of the oil changes and the primary oxidation products — hydroperoxides — are formed. Vegetable-based oil oxidation products do not form a precipitate. Instead, the oil begins to thicken and polymerize. The developed method of diagnosing of an insulating liquid is to determine a coefficient proportional to the growth rate of the number of polar molecules in oil. The results show that monitoring only the tangent of dielectric losses does not give information of the state of vegetable-based oil and is not always an indicator of oxidative processes in oil. The thermal oxidation process has a steady effect on the dielectric constant, which indicates changes of the oil as a result of polymerization.

Deactivation of the catalytic complex of obtaining alkylbenzenes by oxygenate compounds

The possibility of environmentally safe and energy-saving deactivation of the catalytic complex based on aluminum chloride used in the process of alkylation of benzene with olefins, oxygenate compounds – epoxy soybean oil, propylene oxide and isopentane oxidation products is shown. It has been established that the deactivating ability increases in the series: oxygenates → propylene oxide → epoxidized soybean oil (ESBO).

Engine Oil Degradation Induced by Biodiesel: Effect of Methyl Oleate on the Performance of Zinc Dialkyldithiophosphate.

In the present work, the oxidation stability of blends of methyl oleate, zinc dialkyldithiophosphate (ZDDP), and a high viscosity index mineral base oil was determined by the method of a rotating pressure vessel, while the antiwear abilities were evaluated on a four-ball friction tester. Thereafter, the thermal decomposition characteristics and oxidation products of the oxidized blends were analyzed by a thermogravimetric analyzer and a gas chromatograph coupled to a mass spectrometer, respectively. The results showed that the antioxidation ability of ZDDP was substantially improved by methyl oleate, while the antiwear capacity is markedly impaired by methyl oleate. Furthermore, the thermal decomposition characteristics and oxidation products of ZDDP-containing oils were altered by methyl oleate. The present study evidently convinced that chemical interactions between ZDDP and methyl oleate had occurred, which were attributed to the increased antioxidation ability and decreased antiwear capacity of ZDDP in oils contaminated with methyl oleate.

Effect of biologically active substances on oxidative stability of flaxseed oil.

The enrichment of flaxseed oil, which is a valuable plant source of PUFA omega-3, fat-soluble vitamins and other biologically active substances (BAS), makes it possible to strengthen the therapeutic and prophylactic effect of flaxseed oil. The study of the effect of BAS additives on the oxidative stability of flaxseed oil is an important step in the process of creating products based on enriched flaxseed oil. Experiments were conducted to investigate the influence of added BAS (coenzyme Q10, β-carotene, lutein, zeaxanthin, α-tocopherol, α-tocopherol acetate, cholecalciferol, selenomethionine) on flaxseed oil oxidation stability. Kinetic data on accumulation of primary and secondary oxidation products, free fatty acids in flaxseed oil, as well as the consumption of BAS added to the oil during its storage, were obtained. Experimental results showed that the BAS could have both antioxidant and pro-oxidant properties depending on their chemical structure and concentration. Coenzyme Q10, carotenoids and selenomethionine at concentrations higher than 100, 10 and 0.5mg/100g respectively, accelerate significantly (p < 0.05) the oxidation of flaxseed oil. An addition of 5mg/100g β-carotene inhibits formation of flaxseed oil oxidation products. The co-influence of synthetic and natural oxidation inhibitors with BAS on oxidative stability of flaxseed oil was studied. The fat-soluble esters of ascorbic acid and their compositions with natural antioxidants based on beans and soybeans appeared to be effective and safe stabilizers of flaxseed oil enriched with BAS. Resulting from the studies, new oxidation-resistant functional food products based on flaxseed oil are launched into manufacturing.