Oxidative Stability in Bulk Oil Containing Carbohydrates Such as Glucose,Sucrose, Maltose,Mannitol, and Starch

Effects of carbohydrates including glucose, sucrose, maltose, mannitol, and starch on the oxidative stability of corn oils were evaluated at 40 °C for 51 days, at 100 °C for 17 h, and at 180 °C for 90 min. The degree of oxidation was determined by headspace oxygen content, conjugated dienoic acid (CDA) assay, or p-anisidine value (p-AV) and the moisture content of the oils was analyzed. Starch showed pro-oxidant properties whereas mannitol acted as an antioxidant at all tested temperatures. However, glucose, sucrose, and maltose showed different properties depending on the temperature and type of assays. At 40 °C, glucose, sucrose, and maltose showed antioxidant properties in headspace oxygen and CDA assays. There were no significant differences in CDA between samples at 100 and 180 °C. p-AV in samples containing glucose were significantly higher than those in controls at 180 °C, which may be due to the formation of volatiles from caramelization rather than lipid oxidation. Moisture content of oils containing glucose and starch was significantly higher than that of controls, whereas that of oils containing mannitol was lower than in the control (p < 0.05). Changes in moisture content of oils may be due to the migration of moisture from added carbohydrates into the oils.     

The start‐up of anaerobic sequencing batch reactors at 20 °C and 25 °C for the treatment of slaughterhouse wastewater

The objective of this research was to evaluate the feasibility, the stability and the efficiency of a start‐up at 20 °C and 25 °C of anaerobic sequencing batch reactors (ASBRs) treating slaughterhouse wastewater. Influent chemical oxygen demand (COD) and suspended solids concentrations averaged 7500 and 1700 mg dm^?3, respectively. Reactor start‐up was completed in 168 and 136 days at 20 °C, and 25 °C, respectively. The start‐up process was stable at both temperatures, except for a short period at 20 °C, when effluent volatile fatty acid (VFA) concentrations increased from an average of 40 to 400 mg dm^?3. Effluent quality varied throughout start‐up, but in the last 25 days of the experiment, as the ASBRs were operated under organic loading rates of 2.25 ± 0.21 and 2.86 ± 0.24 kg m^?3 d^?1 at 20 °C and 25 °C, respectively, total COD was reduced by 90.3% ± 1.3%. Methanogenesis was not a limiting factor during start‐up. At 20 °C, the limiting factor was the acidification of the soluble organics and, to a smaller extent, the reduction of propionic, isobutyric and isovaleric acids into lower VFAs. At 25 °C, the limiting factor was the hydrolysis of particulate organics. To minimize biomass loss during the start‐up period, the organic loading rate should be increased only when 75 –80% of the COD fed has been transformed into methane within the design hydraulic retention time. © 2001 Society of Chemical Industry     

Evaluation of Oxygen-Limitation on Lipid Oxidation and Moisture Content in Corn Oil at Elevated Temperature

The role of oxygen-limitation on lipid oxidation and moisture content were tested in corn oil heated to 60, 100, and 140 °C. The degree of oxidation was determined by analyzing headspace oxygen content, conjugated dienoic acids (CDA), and p-anisidine value (p-AV). The moisture content in bulk oil was analyzed by the Karl Fischer method. Oxygen-limited samples heated to 100 and 140 °C had significantly more lipid oxidation than oxygen-unlimited samples at early timepoints (p < 0.05). After this period, the oxygen-unlimited samples had more lipid oxidation based on CDA and p-AV assays. During those initial periods, oxygen-limited samples had significantly higher moisture content than oxygen-unlimited samples (p < 0.05), which implies that moisture content in oils plays an important role in the rate of lipid oxidation. The increased moisture content in bulk oil under oxygen-limited conditions is due to headspace moisture rather than moisture inside the oil. However, the effects of oxygen-limitation on lipid oxidation were less clear at 60 °C than at 100 or 140 °C.     

Influence of initiator on the curing of unsaturated polyester resin at 100 °C

Sheet molding compound (SMC) parts are fiber‐reinforced unsaturated polyester (UP) composites molded at 140–170 °C under a pressure of 60–100 bar. For economic and ecological reasons, the aim of this research project is to develop new SMC formulations to modify the molding conditions. For this, SMC formulations were modified and optimized to decrease the molding temperature to 100 °C. The strategy was to change the catalytic system (peroxides) in order to obtain highly reactive formulations at 100 °C. First, the temperatures of initiation of the reaction were determined by rheological and DSC measurements for each peroxide. Second, the UP resin crosslinking kinetics were measured for the various peroxides during an isothermal curing at 100 °C. The results obtained with the three experimental methods are compared and discussed. Finally, the laboratory analyses were validated by SMC molding trials. © 2019 Society of Chemical Industry     

Chemical Compositions of Walnut (Juglans regia L.) Oils from Different Cultivated Regions in China

This study is a comprehensive report on the quality of Chinese walnut oil, which enriches the research of oil resources. A total of 16 walnut samples from China were selected, and walnut oils were obtained using the pressing process. The lipid compositions and micronutrient contents were analyzed. The fatty acids corresponded to palmitic acid (3.05–8.25%), oleic acid (12.56–26.03%), linoleic acid (51.21–68.97%), and linolenic acid (6.83–15.01%), and the main triacylglycerols were trilinolein (27.87–39.47%), followed by oleoyl‐linoleoyl‐linolenoyl‐glycerol (17.07–24.18%), dilinoleoyl‐oleoyl‐glycerol (9.65–15.46%), palmitoyl‐dilinoleoyl‐glycerol (5.96–14.98%), and dilinoleoyl‐linolenoyl‐glycerol (6.42–12.43%). In addition, high amounts of micronutrients, including phytosterol, squalene, tocopherol, and total phenolic content, were found in walnut oils ranging from 540 to 1594, 17 to 131, 345 to 1280, and 1.04 to 20.39 mg kg^?1 among different samples, respectively. The differences in the geographical location and climate caused different regions of cultivation, which resulted in the differences in the chemical composition of walnut oil. Further multiple linear regression analyses between oxidative stability indices, fatty‐acid compositions, and micronutrients revealed that linoleic acid (R = ?0.891; P < 0.05), α‐tocopherol (R = 0.713; P < 0.05), and total phenolic content (R = 0.369; P < 0.05) were the main factors that affect the oxidative stability of the walnut oil.     

Investigation of emissions from heated essential‐oil‐rich fuels at 200 °C

Essential oil of fuels is closely linked with the behavior of forest fires, especially high intensity fires and eruptive fires. It is assumed that the potential reason is the large quantities of flammable gases released from essential oil‐rich fuels before pyrolysis in fire environment. However, few studies have been carried out on the hypothesis. The purpose of the present study is to investigate the emissions from essential oil‐rich fuels. The fuels were collected from three coniferous species. In the experiment, needles and twigs were heated in a vacuum oven at 200 °C, and the emissions within 15 min had been sampled using Tenax tubes. Gas chromatography–mass spectrometry served as an analytical instrument. The results showed that the emissions contained high proportion of monoterpenes, such as α‐pinene, camphene, β‐pinene, 3‐carene, and d ‐limonene. The monoterpene emissions from heated needles and twigs of Pinus pumila, Larix gmelinii, and Pinus sylvestris were 61.221, 49.606, and 37.853 µg g^?1 dry weight (needles), and 211.727, 139.957, and 121.505 µg g^?1 dry weight (twigs), respectively. Statistical analyses showed the significant differences not only among species but also between needles and twigs. Copyright © 2012 John Wiley & Sons, Ltd.     

Oxidation kinetics in olive oil triacylglycerols under accelerated shelf‐life testing (25–75 °C)

A kinetic study of the autoxidation reaction in olive oil triacylglycerols stored in darkness at different temperatures (25, 40, 50, 60 and 75 °C), in absence of pro‐ and antioxidant compounds to avoid confounding effects, is described. After the induction period (IP) the decrease in the oxidizing substrate and the formation of primary oxidation products followed a pseudo‐zero‐order kinetic, and the calculated E_a from the Arrhenius equation for the formation of hydroperoxides was 32.1 kJ·mol^?1. The formation of secondary oxidation products followed a pseudo‐first‐order kinetic whose rate reaction constant also increased exponentially with temperature. The first oxidation index to exceed the upper limit in the EU regulations was PV, followed by K₂₃₂ and K₂₇₀. The time required reaching these limits and the rancidity threshold showed a potential dependence on temperature, and therefore with accelerated storage at 75 °C, POO shelf‐life in ambient conditions (25 °C) can be predicted. Finally, there was a good linear relationship between the time required to reach the rancidity threshold and the IP of the formation of the 2,4‐decadienal, and hence this instrumental determination could be useful to measure sensory recognition of the rancid defect in POO.     

Interfacial reaction of stannic oxide in silicone rubber at 300°C

The thermal stability of high-temperature vulcanized silicone rubber with stannic oxide as a heat stabilizer was investigated by heat aging at 300°C × 24 h in air. It was discovered that Sn⁺⁴ is reduced to Sn⁰ during vulcanization and during heat aging in air by X-ray photoelectron spectroscopy (XPS). © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2779–2781, 1999     

The Free Fatty Acid Content of Fish Oil,Part III: The Influence of Different Variables on Free Fatty Acid Formation during Storage of Anchovy Oil at 25°C

Long-term storage of fish oils frequently leads to deterioration in quality due to enzymatic formation of free fatty acids (FFA). The present investigation has identified a number of chemical characteristics which can serve as indices in predicting which oils are liable to show FFA escalation on storage. It also outlines measures to be taken to prevent FFA escalation.     

Differences in Oxidative Stability,Sensory Properties,and Volatile Compounds of Pepper Aromatized Sunflower Oils Prepared by Different Methods during Accelerated Storage

The study aims to compare the differences in the oxidative stability, sensory properties, and volatile compounds during accelerated storage of pepper aromatized sunflower oil (PASO) samples prepared by maceration method (PASO-M), co-pressing method (PASO-C), and direct addition method (PASO-A), respectively. The results exhibit that their oxidative stability is in the relative order: PASO-A > PASO-C > PASO-M. Meanwhile, the PASO-A sample is the most preferable aromatized sunflower oil by consumers according to sensory analysis. In addition, a total of 83 volatile compounds are identified in the three PASO samples during the storage, and the principal component analysis (PCA) shows that their volatile compounds are quite different at the initial stage of the storage. Still, they are similar among each other from the middle of storage period. As consequence, the aromatized sunflower oil sample prepared by the direct-addition method during the storage possesses better oxidative stability and sensory attributes, and there is not much difference among their volatile compounds, indicating that the aromatized sunflower oil prepared by direct-addition method can be developed as promising aromatized sunflower oil. Practical applications: This study shows that aromatization increases oxidative stability and sensory properties of sunflower oil. By this way some sunflower oils with special sensory properties are obtained: special smell and taste, special color, etc. These peppers aromatized sunflower oils can be used to increase taste and smell in some dishes. For example, they can be used in some salads and some roast meats to give more taste and color.     

Influence of the reaction conditions on the thermal stability of mesoporous MCM-48 silica obtained at room temperature

The thermal stability of MCM-48 silicas synthesized at room temperature under basic conditions using cetyltrimethylammonium bromide (CTAB) as template was evaluated as a function of the reaction time, CTAB/TEOS and H₂O/ethanol molar ratios and ammonium hydroxide (NH₄OH) concentration in the initial gel composition. Samples were characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption analyses, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that synthesis conditions affect the structural and thermal properties of the MCM-48 silicas. These silicas exhibited a size from 200 to 500 nm with spherical morphology.     

Effects of Seed Coat on Oxidative Stability and Antioxidant Activity of Apricot (Prunus armeniaca L.) Kernel Oil at Different Roasting Temperatures

Apricot kernels were roasted at various temperatures (120–180 °C) for 10 min and changes in the fatty‐acid profiles, oxidative stability, and antioxidant activity, as well as the total phenolic contents (TPC) of the oils and skin (seed coat), were monitored. Roasting has no obvious influence on profiles and contents of fatty acid, induction period (IP), browning index, TPC, and antioxidant activity (2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), 2,2‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid), (ABTS) and Oxygen Radical Absorbance Capacity (ORAC) of oils obtained from apricot naked‐kernel, but increases IP, TPC, and oxidative stability in oils obtained from apricot kernel with skin. All results in the present work demonstrated that thermal treatment accelerated the production and transference of alcohol‐soluble phenolics into the oil, and improved the oil oxidative stability. It is not Maillard reaction products but alcohol‐soluble phenolic compounds in skins that play a role in improving the oxidative stability and antioxidant activity of oils, and inhibition for primary peroxide production was more effective than secondary peroxide production at a low roasting temperature and a short roasting time. The present findings can advance knowledge on the conditions used for utilization of coproducts (skin) of apricot kernel and facilitate large‐scale production of stable oil against oxidation.     

Factors Influencing the Stability of AFm and AFt in the Ca–Al–S–O–H System at 25°C

The stabilities of Al₂O₃–Fe₂O₃‐mono (AFm) and ‐tri (AFt) phases in the Ca–Al–S–O–H system at 25°C are examined using Gibbs energy minimization as implemented by GEM‐Selektor software coupled with the Nagra/PSI thermodynamic database. Equilibrium phase diagrams are constructed and compared to those reported in previous studies. The sensitivity of the calculations to the assumed solid solubility products, highlighted by the example of hydrogarnet, is likely the reason that some studies, including this one, predict a stable SO₄‐rich AFm phase while others do not. The majority of the effort is given for calculating the influences on AFm and AFt stability of alkali and carbonate components, both of which are typically present in cementitious binders. Higher alkali content shifts the equilibria of both AFt and AFm to lower Ca but higher Al and S concentrations in solution. More importantly, higher alkali content significantly expands the range of solution compositions in equilibrium with AFm. The introduction of carbonates alters not only the stable AFm solid solution compositions, as expected, but also influences the range of solution pH over which SO₄‐rich and OH‐rich AFm phases are dominant. Some experimental tests are suggested that could provide validation of these calculations, which are all the more important because of the implications for resistance of portland cement binders to external sulfate attack.     

Fabrication of BaZr0.1Ce0.7Y0.2O3 – δ ‐Based Proton‐Conducting Solid Oxide Fuel Cells Co‐Fired at 1,150 °C

Dense proton‐conducting BaZr_0.1Ce_0.7Y_0.2O_{3 – δ} (BZCY) electrolyte membranes were successfully fabricated on NiO–BZCY anode substrates at a low temperature of 1,150 °C via a combined co‐press and co‐firing process. To fabricate full cells, the LaSr₃Co_1.5Fe_1.5O_{10 – δ}–BZCY composite cathode layer was fixed to the electrolyte membrane by two means of one‐step co‐firing and two‐step co‐firing, respectively. The SEM results revealed that the cathode layer bonded more closely to the electrolyte membrane via the one‐step co‐firing process. Correspondingly, determined from the electrochemical impedance spectroscopy measured under open current conditions, the electrode polarisation and Ohmic resistances of the one‐step co‐fired cell were dramatically lower than the other one for its excellent interface adhesion. With humidified hydrogen (2% H₂O) as the fuel and static air as the oxidant, the maximum power density of the one‐step co‐fired single cell achieved 328 mW cm^–2 at 700 °C, showing a much better performance than that of the two‐step co‐fired single cell, which was 264 mW cm^–2 at 700 °C.