High Oxidative Stability Research Articles

DABCOnium: An Efficient and High-Voltage Stable Singlet Oxygen Quencher for Metal-O2 Cells.

Singlet oxygen (1O2) causes a major fraction of the parasitic chemistry during the cycling of non‐aqueous alkali metal‐O2 batteries and also contributes to interfacial reactivity of transition‐metal oxide intercalation compounds. We introduce DABCOnium, the mono alkylated form of 1,4‐diazabicyclo[2.2.2]octane (DABCO), as an efficient 1O2 quencher with an unusually high oxidative stability of ca. 4.2 V vs. Li/Li+. Previous quenchers are strongly Lewis basic amines with too low oxidative stability. DABCOnium is an ionic liquid, non‐volatile, highly soluble in the electrolyte, stable against superoxide and peroxide, and compatible with lithium metal. The electrochemical stability covers the required range for metal–O2 batteries and greatly reduces 1O2 related parasitic chemistry as demonstrated for the Li–O2 cell.

Improvement of the tribological behaviour of palm biodiesel via partial hydrogenation of unsaturated fatty acid methyl esters

Partial hydrogenation of unsaturated fatty acid methyl esters, the so-called H-FAME, has been developed, particularly for application in warm climates, to improve the oxidation stability of biodiesel. During the H-FAME process, polyunsaturated ester molecules, which are a primary cause of biodiesel induced oxidation, can be reduced. In this paper, the lubrication properties and mechanisms have been studied when high quality biodiesel from palm was upgraded to H-FAME. Lubricity tests were performed using a high-frequency reciprocating rig (HFRR). After the lubricity tests, wear scar and deposits on the tested specimens were analyzed using a scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectrometry (EDS). It was found that the partial hydrogenation upgrading process reduced polyunsaturated molecules and also transformed cis-monounsaturated molecules (C18:1 cis) into trans-monounsaturated molecules (C18:1 trans). This increased the stability of the lubricating film when C18:1 trans molecules were present, and so improved the lubricity of the H-FAME. An observation of wear damage suggested that the H-FAME was able to form dense and stable tribo-films on the steel test surfaces, protecting them from abrasive damage such as scoring and scratching. As a result of the reduction of polyunsaturated ester molecules, the lubricity of the H-FAME was less sensitive to the changes in humidity. Moreover, there was evidence of a reduction in both corrosive wear and large agglomerations of deposits for the H-FAME upgraded palm biodiesel due to its higher oxidation stability.

Biobased Poly-phosphonate Additives from Methyl Linoleates

Poly-dialkyl phosphonates were synthesized by reacting methyl linoleate with dimethyl, diethyl, and di-n-butyl phosphites in the presence of free radical initiator and positively identified and characterized using gas chromatography–mass spectrometry (GC-MS), nuclear magnetic resonance (NMR; 1H, 13C, 31P), and Fourier transform infrared (FTIR). Neat poly-dialkyl phosphonates and their blends in high-oleic sunflower oil (HOSuO) and polyalphaolefin (PAO-6) base oils were investigated for their physical, chemical, and tribological properties. At room temperature, the poly-dialkyl phosphonates displayed much better solubility in HOSuO than in PAO-6. Solubility in the base oils increased in the order dimethyl < diethyl < di-n-butyl. Relative to methyl linoleate, the neat poly-dialkyl phosphonates displayed higher density, higher kinematic viscosity, higher oxidation stability, and better cold flow (lower pour point and cloud point) properties. As an additive (0–10% w/w) in HOSuO, increasing concentration of poly-di-n-butyl phosphonate resulted in increasing onset and peak oxidation temperatures and decreasing cloud point. Poly-di-n-butyl phosphonate blends in HOSuO also showed lower four-ball antiwear (AW) coefficient of friction (COF) and wear scar diameter (WSD) than corresponding blends with zinc dialkyl dithiophosphate (ZDDP). As an additive (0–10% w/w) in PAO-6 base oil, poly-di-n-butyl phosphonate displayed lower four-ball antiwear COF and comparable WSD relative to similar blends of ZDDP in PAO-6. The results indicate that poly-dialkyl phosphonates are promising biobased AW additives with comparable or better performance than current petroleum-based commercial AW additives such as ZDDP.

Covalent Interaction between Rice Protein Hydrolysates and Chlorogenic Acid: Improving the Stability of Oil-in-Water Emulsions.

Protein hydrolysates, as surfactants, can scavenge radicals, but their poor distributions at the oil-water interface limit their storage stability. Therefore, we studied covalent interaction between rice protein hydrolysates and chlorogenic acid under alkaline conditions to improve the physical and oxidative stability of oil-in-water emulsions. Turbidity and particle size measurements demonstrated the formation of hydrolysates-chlorogenic acid complexes, and their covalent interaction resulted in the decrease and redshift of the fluorescence intensity. The emulsifying activity of the hydrolysates could be effectively improved after the covalent interaction with 0.025% chlorogenic acid. The modified emulsions possessed a notable physical stability according to the least changes in size (0.08 μm) and ζ-potential (3.34 mV) of the emulsion ( P > 0.05). Moreover, the covalent interaction endowed modified emulsions with high oxidative stability to effectively inhibit lipid oxidative deterioration during storage. The adsorption of hydrolysates to the emulsion interface was increased by the adequate addition of chlorogenic acid, which resulted in the oil droplet being surrounded by a thicker interfacial film. The covalent interaction between the protein hydrolysates and chlorogenic acid could be used to construct natural emulsion systems with a higher physical and oxidative stability during storage.

Effects of packaging and storage conditions on Iranian wild pistachio kernels and assessment of oxidative stability of edible extracted oil

In the present research, Baneh Kernels (BK) (Pistacia atlantica var mutica, wild pistachio) were packaged with laminated-type pouches of polyethylene/polyamide/polyethylene and polyester/aluminum foil/low-density polyethylene (PET/AL/LDPE) under two packaging conditions (vacuum and conventional conditions) and were stored for 12 weeks at 20, 35, and 50°C. The oil of each sample was extracted and was evaluated for peroxide value, carbonyl value, total tocopherol, and total phenolic contents. No significant difference (p < 0.05) between the peroxide and carbonyl values at 20 and 35°C was observed while only an increase in these parameters (with a very small slope) was noted at 50°C. High levels of oxidative stability of BK samples can be correlated with low reduction in the content of antioxidants, especially tocopherols during storage, while it (reduction) was noted as17.9% in the worst condition. In this regard, (PET/AL/LLDPE) under vacuum was identified as the best packaging condition. Practical applications Baneh Kernels (BK) can be used as a good source of oil due to high oxidative stability. Moreover, the suitable packaging material for BK as well as an adjusted storage condition until processing (extraction) could play an important role in improving oxidative stability. In this context, the introduced packaging in this study can be approached to keep the quality of BK. Also, the proposed temperature could reduce the adverse effects of storage before processing.

A Cooperative Effect in a Novel Bimetallic Mo-V Nanocomplex Catalyzed Selective Aerobic C-H Oxidation.

In this study, a new heterobimetallic Mo(VI)–V(V) organosilicon Schiff base complex has been prepared and characterized by different techniques, such as FTIR, Raman, MS, ICP-AES, TGA, and XPS. The bimetallic nanocomplex, revealed by TEM images, showed high oxidation stability and desired activity in the aerobic oxidation of a structurally diverse set of benzylic alcohols in ethanol as a safe solvent. Further, oxidation of benzylic hydrocarbons successfully occurred, producing the target compounds in high yields and excellent selectivities. Our results demonstrated a cooperative effect between Mo(VI) and V(V) as redox active sites in an organosilicon Schiff base framework. A facile and practical reusability of the solid catalyst at the end of the reaction was observed.

Overcoming the High-Voltage Limitations of Li-Ion Batteries Using a Titanium Nitride Current Collector

The major obstacle to commercialization of high-voltage Li-ion batteries is the lack of oxidatively stable and inexpensive current collectors that can operate at potentials of up to 5 V vs Li+/Li. In this work, we present titanium nitride as a compelling cathode current collector for high-voltage Li-ion batteries exhibiting higher oxidative stability in LiPF6 and lithium bis(fluorosulfonyl)imide electrolytes than aluminum or stainless steel current collectors. Its high oxidative stability has been assessed with a high-voltage LiMn1.5Ni0.5O4 cathode. TiN/LiMn1.5Ni0.5O4 half cells demonstrated a high Coulombic efficiency of 98.5% at a low C-rate of 0.2 C after 100 cycles.

Prediction of Palm Based Biodiesel Properties Through the Preparation of Empirical Equation

Biodiesel is one of plant-based fuel that has been made mandatory by the Indonesian government for using in transportation, industries, and power plants. This obligation is gradually applied as stipulated in the regulation of the Ministry of Energy and Mineral Resources 12/2015 regarding to supply, use and plant-based fuel trade as alternative fuel. The percentage of biodiesel use was increasing from 20 % in 2016 to 30 % in 2030. The quality of biodiesel has to be continuously improved to support the regulation. Biodiesel with high performance has excellent flame characteristics, high oxidation stability and easy to flow at low temperature. These characteristics are highly determined by the composition of fatty acid methyl esters (FAME). Empirical equations were formulated based on primary data to predict the essential parameters of biodiesel, consisting of oxidation stability, cloud point, Iodine value, viscosity and density. The primary data were obtained by analyzing three biodiesel samples from domestic producers and two samples of biodiesel blend between palm stearin and soybean biodiesel. Identification results showed that all three samples have different FAME profiles which consist of palm oil biodiesel, palm stearin biodiesel and palm olein biodiesel. The empirical equations were formulated using statistical software and validated by comparing the calculated results with actual biodiesel parameters. This method reduced the testing time up to 13 working days and reduced testing cost up to 67% or IDR 1 190 000 per sample. The empirical equations formulated in this study were able to predict the essential parameters of biodiesel with the error was.

Oxidative stability and thermal performance of ester based lube oil with lithium salt additives

In the present study, the performance of bis(trifluoromethylsulfonyl)amine lithium (LiTFSI) and lithium tetrafluoroborate (LiBF4) salts as a novel lubricant additive was assessed. The oxidative stability of ester based lube oil (L2) when mixed with LiTFSI and LiBF4 (1.0 and 5.0 mass%) was estimated by calorimetric techniques combined with the thermokinetic model. A significant improvement in the viscosity index by 8.0% was observed when 5.0 mass% LiTFSI was used. Thermogravimetric analysis revealed two major mass loss steps between 98.0 and 336.0 °C and 292.0 to 454.0 °C at different heating rates. The chemical composition of treated samples revealed the formation of octatriacontyl pentafluoropropionate complex, which could be responsible for the increase in thermal stability of L2. The estimated average value of apparent activation energy (Ea) of L2 was 82.5 kJ·mol−1. The 5.0 mass% LiTFSI sample had the highest oxidative stability, and the kinetic models revealed that the Ea was 121.1 kJ·mol−1. The thermal performance of lubricant oil could be improved by increasing the concentration of Li salt additives up to 5.0 mass%.

Expression of the Arabidopsis WRINKLED 1 transcription factor leads to higher accumulation of palmitate in soybean seed.

SummarySoybean (Glycine max [L.] Merr.) is a commodity crop highly valued for its protein and oil content. The high percentage of polyunsaturated fatty acids in soybean oil results in low oxidative stability, which is a key parameter for usage in baking, high temperature frying applications, and affects shelf life of packaged products containing soybean oil. Introduction of a seed‐specific expression cassette carrying the Arabidopsis transcription factor WRINKLED1 (AtWRI1) into soybean, led to seed oil with levels of palmitate up to approximately 20%. Stacking of the AtWRI1 transgenic allele with a transgenic locus harbouring the mangosteen steroyl‐ACP thioesterase (GmFatA) resulted in oil with total saturates up to 30%. The creation of a triple stack in soybean, wherein the AtWRI1 and GmFatA alleles were combined with a FAD2‐1 silencing allele led to the synthesis of an oil with 28% saturates and approximately 60% oleate. Constructs were then assembled that carry a dual FAD2‐1 silencing element/GmFatA expression cassette, alone or combined with an AtWRI1 cassette. These plasmids are designated pPTN1289 and pPTN1301, respectively. Transgenic events carrying the T‐DNA of pPTN1289 displayed an oil with stearate levels between 18% and 25%, and oleate in the upper 60%, with reduced palmitate (<5%). While soybean events harboring transgenic alleles of pPTN1301 had similar levels of stearic and oleate levels as that of the pPTRN1289 events, but with levels of palmitate closer to wild type. The modified fatty acid composition results in an oil with higher oxidative stability, and functionality attributes for end use in baking applications.

Formulation of Pickering sunflower oil-in-water emulsion stabilized by chitosan-stearic acid nanogel and studying its oxidative stability

The aim of this study was to obtain a stable sunflower oil-in-water (O/W) Pickering emulsion stabilized by chitosan (CS)-stearic acid (SA) nanogels and to compare the oxidative stability of the sunflower Pickering emulsion stabilized by CS-SA nanogels with sunflower oil emulsion stabilized by Tween 80. The results of the scanning electron microscopy revealed that by increasing the SA to CS ratio, the uniformity of particles was increased. Also, the results showed that the emulsions with pH of 8, SA to CS ratio of 0.5:1, and oil-to-nanogel ratio of 20:1 had the highest stability and minimum droplet size. In the following, the oxidative stability of the most favorable Pickering emulsion and the Tween 80-stabilized emulsion was evaluated and compared using the peroxide and thiobarbituric acid tests. The findings implied that the O/W emulsion stabilized by CS-SA nanogels had a higher oxidative stability than the O/W emulsion stabilized by Tween 80.

Seed Storage Indicates the High Stability of Babaçu Oil (Attalea vitrivir Zona)

Because the baba&amp;ccedil;u palm (Attalea vitrivir) has been considered for incorporation into programs of biofuel production, in this work we evaluated the influence of the geographic origins and storage conditions of baba&amp;ccedil;u palm seeds on the quantity and quality of their extracted oils. Seeds harvested from three different areas were stored for 12 months under natural environmental conditions (mean temperature 25 &amp;ordm;C), under refrigeration (4 &amp;ordm;C), or in a freezer (-20 &amp;deg;C). We determined their water and oil contents, acidity and peroxide levels, refractive indices, and their fatty acid profiles. The original water content of the seeds was 4.9%, becoming reduced by half during storage. Oil represented 53% of the seed weight, with lauric acid predominating throughout storage. The seed oil demonstrated high oxidative stability, with low levels of acidity and peroxide formation, independent of seed origin or storage conditions. The high quality of Attalea vitrivir oil and its stability confirm its potential for agroindustrial use.

Impact of pretreatment‐assisted enzymatic extraction on recovery, physicochemical and rheological properties of oil from Labeo rohita head

AbstractEffects of pretreatments, namely heating (HT), microwave (MW), and ultrasound (US) followed by the enzymatic extraction on extraction yield, fatty acid profile (FAP), oxidative stability, and rheological properties of oil from Labeo rohita head (LRH) were investigated. MW and US pretreatments showed higher oil recoveries ranged from 68.45 to 69.75% and 58.74 to 67.48%, respectively, as compared to untreated LRH. US pretreatment enhanced the content of monounsaturated fatty acid and polyunsaturated fatty acid of LRH oil. Furthermore, MW pretreatment reduced the stability of LRH oil, while US pretreatment did not affect the oxidative stability of LRH oil as evidenced by differential scanning calorimetry analysis and peroxide value, anisidine value, thiobarbituric acid‐reactive substances, and free fatty acid values. Besides, all oils behaved as Newtonian fluids. US extracted oil has shown both the lowest apparent viscosity and sensitivity to temperature change (Ea = 29.74 kJ/mol). Therefore, MW or US‐assisted enzymatic extraction of LRH oil could be a good alternative to conventional enzymatic extraction.Practical applicationsMicrowave (MW) and ultrasound (US) pretreatments improved the extraction yield of oil significantly from Labeo rohita head (fish byproduct) compared to conventional enzymatic extraction. The oil extracted by US pretreatment was found to have a high content in unsaturated fatty acids and higher oxidative stability over enzymatic extracted oil. Thus, the results revealed that the MW or US‐assisted enzymatic extraction was a promising method for the improvement of the extraction yield of Labeo rohita head oil with high quality.

Biodiesel Potentiality of Microalgae Species: evaluation Using Various Nitrogen Sources

The two fresh water microalgae species namely Scenedesmus dimorphus and Scenedesmus obliquus were selected as biomass feedstocks for biodiesel production due to high accumulation of their neutral lipid content which mainly composed of three significant biodiesel fatty acids profile viz saturated fatty acids (SFA: ≈ 53%), mono unsaturated fatty acids (MUFA: ≈ 24%) and poly unsaturated fatty acids (PUFA: ≈ 20%). Both algae strains were cultivated with five different nitrogen nutrients via (NH4)2SO4 (ammonium sulphate: AS), NH4NO3 (ammonium nitrate: AN), KNO3 (potassium nitrate: PN), (NH2)2CO (urea: UR) and NaNO3 (sodium nitrate: SN) of concentration ranging from 0.02 to 0.3 M in agricultural medium. The transesterification of micro algal lipids with absolute ethanol medium in the presence of Ni/H2 catalyst and Ni(II)–Schiff base chelate promoter was carried out to yield more algal oil. The extracted biodiesel components were analyzed cost–effectively using UV–Vis,1H NMR, 13C NMR and GC–MS spectral characterization to explore their biodiesel potentiality. The results revealed that the extracted microalgae biodiesels are quite suitable for biodiesel production with higher oxidation stability and cetane number. In this study, S. dimorphus and S. obliquus in the presence of five different nitrogen nutrients of concentration ranging from 0.02 to 0.3 M agar in cultural medium were observed to stimulate them to produce lipid for biodiesel generation. The transesterification of micro algal lipids with absolute ethanol medium in the presence of Ni/H2 catalyst and Ni(II)–Schiff base chelate promoter was carried out to yield more algal oil. The fatty acid composition of the extracted micro algal oils have been identified via UV–Vis, NMR and GC–MS spectral characterization techniques to investigate their biodiesel potentiality. It is noted that increased UR concentration (up to 0.3 M) can effectively enhances biomass production of S. dimorphus and S. obliquus as increased urea levels may enhances biomass production excluding cells may have a low lipid content, at times.

Characterization of Ternary Blends of Vegetable Oils with Optimal ω-6/ω-3 Fatty Acid Ratios.

An optimal ratio of omega-6 to omega-3 (ω-6/ω-3) polyunsaturated fatty acids (PUFA) in the diet prevents the pathogenesis of many inflammatory diseases. This study aimed to synthesize and characterize ternary oil blends with optimal ω-6/ω-3 ratios using olive (OL), sunflower (SU), and cress (CR) oils. The oxidative stability, thermal profile, fatty acid (FA) and tocopherol compositions, and the physicochemical properties of the blends were used to determine their quality. Oil mixtures were prepared with 2, 3, 4, and 5 ω-6/ω-3 ratios. FA composition and tocopherol content were the most important factors affecting the oxidation and thermal stabilities of the oils. All oil mixtures showed good quality indices. Thus, synthetized oil blends with high oxidative stability, high antioxidant content, optimal ω-6/ω-3 ratios, and recommended FA compositions can influence human health. The composition of healthy oil blends with optimal ω-6/ω-3 ratios was expressed mathematically and depicted graphically in a ternary diagram.

LIPID AUTOXIDATION OF FISH, LARD, CORN AND LINSEED OILS BY ISOTHERMAL CALORIMETRY

This work proposes an approach to characterize lipid oxidation of oils based on the measurement of isothermal calorimetry data, including information on the duration of the monomolecular, bimolecular and termination periods. The approach has been exploited with fish and lard oil samples at temperatures from 40 to 80°C and with corn and linseed oils at 80°C. The length of the monomolecular period was the most sensitive to the variation of temperature. Accordingly, the monomolecular period was used as index of oxidative stability of oils. Thus, the highest oxidative stability was observed for corn oil samples at 80°C (tmono = 2060 min), followed by linseed (tmono = 390 min), fish (tmono = 40 min) and lard oils (tmono = 30 min). The different stability of the samples was discussed with their fatty acids profile and antioxidant activity. The results confirmed that the content in natural antioxidants is the key responsible for the final oxidative stability of the samples.

The effect of cation exchange resin treatment of grape must on the chemical and sensory characteristics of base wines for sparkling wine

Ion exchange resins are polymers with high physical and chemical stability, which, upon activation, acquire positive charge (H+) ions which interchange with existing cations during musts or wines treatment. The chemical composition of the grape must, and wines are highly affected by said modifications. This study aimed to evaluate the impact of the cationic resin treatments on the physicochemical and organoleptic characteristics of base white wines for sparkling wine production. Thus for, Chardonnay must was exposed to a cation exchange resin specific for oenological usage, and fermented to obtain wines. Resulting wines included an untreated control sample with pH 3.15 and treated samples with pH 3.08, 3.02 and 2.97. Physicochemical and volatile compounds analyses as well as quantitative sensory evaluations were conducted. The results showed that, on the scenarios tested, treatments with cationic resins before fermentation resulted in wine with higher oxidative stability, with significative variation on the concentration of several volatile compounds that influenced organoleptic perceptions.

Prevention of Fish Oil Oxidation.

The benefit of fish oil to health has been widely recognized because of the high contents of functional EPA (20:5n-3) and DHA (22:6n-3) in the oil; however, the application of fish oil has been limited by its high susceptibility to oxidation. This review reports the characteristics of EPA and DHA oxidation compared with those of other fatty acids such as linoleic acid (18:2n-6). In addition, effective approaches to protect against oxidation are discussed, focusing on the unique antioxidant potential of amine compounds. Finally, the exceptionally high oxidative stability of EPA and DHA in biological systems is discussed. Understanding the protective mechanism against EPA and DHA oxidation in such systems may be useful for the development of an effective antioxidant procedure for fish oil that is rich in EPA and DHA.

Active emulsions based on alginate and lemongrass/citral essential oils: effect of encapsulating agents on physical and antimicrobial properties

ABSTRACTFor the development of a natural antimicrobial additive based on natural compounds (AC) such as lemongrass essential oil and its active compound citral, encapsulating agents (EA) are required to incorporate it inside food matrixes. Therefore, the effects of type and concentration of EA (maltodextrin and modified-starch called Capsul®) on physical and antimicrobial properties of alginate-based and Lemongrass/citral emulsions were evaluated. Emulsions using different AC:EA ratios were prepared, measuring their antimicrobial (Escherichia coli and Listeria innocua) and physical properties. Antimicrobial activities were observed in all emulsions independently of AC:EA ratio and EA or AC types. However, color differences (ΔE2000) depended on AC:EA ratio and AC used. For both AC, samples with maltodextrin showed higher viscosity and physical stability than Capsul® samples, while the latter showed the highest oxidative stability. In conclusion, EA type affected both physical and oxidative stability of alginate-AC-emulsions; however, both EA could be used for the development of natural antimicrobial additives.

High-Quality Biodiesel Production from Buriti (Mauritia flexuosa) Oil Soapstock.

The buriti palm (Mauritia flexuosa) is a palm tree widely distributed throughout tropical South America. The oil extracted from the fruits of this palm tree is rich in natural antioxidants. The by-products obtained from the buriti palm have social and economic importance as well, hence the interest in adding value to the residue left from refining this oil to obtain biofuel. The process of methyl esters production from the buriti oil soapstock was optimized considering acidulation and esterification. The effect of the molar ratio of sulfuric acid (H2SO4) to soapstock in the range from 0.6 to 1.0 and the reaction time (30–90 min) were analyzed. The best conditions for acidulation were molar ratio 0.8 and reaction time of 60 min. Next, the esterification of the fatty acids obtained was performed using methanol and H2SO4 as catalyst. The effects of the molar ratio (9:1–27:1), percentage of catalyst (2–6%) and reaction time (1–14 h) were investigated. The best reaction conditions were: 18:1 molar ratio, 4% catalyst and 14 h reaction time, which resulted in a yield of 92% and a conversion of 99.9%. All the key biodiesel physicochemical characterizations were within the parameters established by the Brazilian standard. The biodiesel obtained presented high ester content (96.6%) and oxidative stability (16.1 h).