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1.
Temperature-Dependent Mechanism of Antioxidant Activity of o-Hydroxyl,o-Methoxy,and Alkyl Ester Derivatives of p-Hydroxybenzoic Acid in Fish Oil
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Reza Farhoosh Ali Sharif Maryam Asnaashari Saeed Johnny Najme Molaahmadibahraseman 《Journal of the American Oil Chemists' Society》2016,93(4):555-567
The autoxidation of purified fish oil in the presence of different concentrations of o‐hydroxyl, o‐methoxy, and alkyl ester derivatives of p‐hydroxybenzoic at 35–55 °C was evaluated by different kinetic parameters including the stabilizing factor as a measure of effectiveness, the oxidation rate ratio as a measure of strength, and the antioxidant activity which combines the two parameters. Methyl gallate as the most reactive antioxidant participated only in the main reaction of chain termination (ROO· + InH ROOH + In·). Gallic acid, ethyl protocatechuate, protocatechuic acid, vanillic acid, and syringic acid, were able to protect fish oil against oxidation in terms of the extent of their participation in the pro‐oxidative side reactions of chain initiation (InH + ROOH In· + RO· + H2O and InH + O2 In· + HOO·) and the antioxidative side reactions of chain propagation (In· + ROO· In‐OOR and In· + In· products). 相似文献
2.
Physicochemical Properties of Mixtures of Morama Seed Oil With Alkanols and Alkyl Acetates at 298.15 K Atmospheric Pressure
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Samuel O. Yeboah Isaac Oathotse Wilfred A. A. Ddamba 《Journal of the American Oil Chemists' Society》2018,95(6):653-663
Densities, ρ, ultrasonic speed, u, and dynamic viscosities, η, of mixtures of morama, Tylosema esculentum, seed oil with 1‐propanol, 1‐butanol, methyl acetate, and ethyl acetate were determined over the entire composition range at 298.15 K and atmospheric pressure. Excess molar volumes, , excess molar‐free volumes , deviations in isentropic compressibility, Δκs, deviations in ultrasonic speed, Δu, deviations in dynamic viscosity, Δη, and the excess free energy of activation of viscous flow, ΔG*E, were calculated and correlated using the Redlich–Kister equation for each of the (morama seed oil + 1‐propanol or 1‐butanol or methyl acetate or ethyl acetate) mixtures. The results obtained were discussed in terms of possible dipole–dipole intermolecular interactions and structural effects. 相似文献
3.
Mechanism of the Inhibitory Effect of Hydroxytyrosol on Lipid Oxidation in Different Bulk Oil Systems
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Hadi Mahdavianmehr Reza Farhoosh Ali Sharif 《Journal of the American Oil Chemists' Society》2016,93(9):1233-1242
The autoxidation of purified triacylglycerols obtained from fish, canola, and olive oils in the presence of different concentrations of hydroxytyrosol at 60–100 °C was evaluated by different kinetic parameters including the stabilizing factor (F) as a measure of effectiveness, the oxidation rate ratio (ORR) as a measure strength, and the antioxidant activity (A) which combines the F and ORR parameters. The overall performance of hydroxytyrosol was attributed to the main reaction of chain termination () as competed with the main oxidation reaction of chain propagation () and, additionally, the antioxidative side reactions of chain propagation ( and ), and the pro‐oxidative side reaction of chain initiation () in some cases. 相似文献
4.
S. O. Yeboah I. Oathotse W. A. A. Ddamba 《Journal of the American Oil Chemists' Society》2014,91(6):1065-1075
Densities ρ, ultrasonic speeds u and dynamic viscosities η, of mixtures of morama, Tylosema esculentum, seed oil with n‐hexane, n‐heptane, n‐octane and n‐nonane were determined over the entire composition range at 298.15 K and atmospheric pressure. Excess molar volumes, , excess molar free volumes , deviations in isentropic compressibility, Δκs, deviations in ultrasonic speed, Δu, deviations in viscosity, Δη, and the excess free energy of activation of viscous flow, ΔG*E, were calculated therefrom and correlated by the Redlich–Kister equation for each of the [morama seed oil + (n‐hexane or n‐heptane or n‐octane or n‐nonane)] mixtures. The results have been discussed in terms of possible intermolecular interactions and structural effects. 相似文献
5.
Andrew P. Karman Susan E. Ebeler Nitin Nitin Stephanie R. Dungan 《Journal of the American Oil Chemists' Society》2021,98(10):979-992
Using headspace solid-phase microextraction (HS–SPME), equilibrium distributions could be determined for hydrophobic solutes in closed systems containing vapor and aqueous solution, either in the absence or presence of two short-chain phospholipids, dihexanoyl-phosphatidylcholine (diC6PC) and diheptanoyl-phosphatidylcholine (diC7PC). Without phospholipid, HS–SPME with short extraction times was used to measure water–vapor partition coefficients for d-limonene at five temperatures within 15–40°C, with results in good agreement with existing literature. The temperature dependence of yielded the enthalpy of volatilization 34.5 kJ/mol for limonene. At 25°C, solubility values for d-limonene, 1-octanol, and n-decane were obtained using similar measurements above aqueous solutions of various solute concentrations. Short-time HS–SPME extraction of limonene in closed vials containing diC6PC or diC7PC micelles was also used to evaluate distributions of solute between vapor, aqueous dissolution, and micelles, for various surfactant concentrations at 15–40°C. Resulting vapor phase concentrations were analyzed using a mass balance and measured values, to obtain micelle–water partition coefficients and critical micelle concentrations. in diC6PC solutions (1–2 mM−1) weakly increased with temperature, but decreased significantly with increased temperature for diC7PC micelles (2–4 mM−1). Solubilization in short-chain PC micelles has previously received little attention, and our results show that the extent of partitioning into these diacyl (i.e., two-tailed) lipids is comparable to that for single-tailed anionic or nonionic surfactants. 相似文献
6.
Hardy Z. Castada Zhaoyu Sun Sheryl A. Barringer Xuesong Huang 《Journal of the American Oil Chemists' Society》2020,97(3):289-300
p-Hydroxybenzoic acid (PHBA) plays a significant role in sustaining the oxidative stability of macadamia nut oil (MNO). However, PHBA undergoes thermal decarboxylation and loses its bioactive antioxidant properties. In this study, we determine PHBA degradation kinetics in oils at various heating temperatures, which provides fundamental understanding of PHBA thermal degradation in oils and oil quality changes during high-temperature processing. PHBA degradation kinetics in MNO, olive oil, and corn oil were evaluated at temperatures typical for cooking and frying. PBHA headspace concentration was measured using selected ion flow tube mass spectrometry. PHBA decarboxylation followed a zero-order reaction, where degradation could be affected by factors such as the type of oil matrix having different FA compositions, antioxidants, and component interactions. PHBA degradation activation energies (E a) showed that PHBA was more stable against thermal decarboxylation in MNO (85 kJ mol–1) than in olive oil (40 kJ mol−1) or corn oil (22 kJ mol−1). The higher enthalpy () of decarboxylation in MNO (82 kJ mol−1) indicates that PHBA is more inhibited from decomposition than olive oil (37 kJ mol−1) or corn oil (19 kJ mol−1). Moreover, the negative entropy values () of PHBA degradation from MNO (−192 J mol−1 K−1), olive oil (−277 J mol−1 K−1), and corn oil (−325 J mol−1 K−1) indicates that these oils impart some inhibitory properties against PHBA thermal decarboxylation. 相似文献
7.
Fernanda Peyronel Joseph Cooney Erzsebet Papp-Szabo Silvana Martini David Pink 《Journal of the American Oil Chemists' Society》2023,100(12):961-974
Three oleogelator molecules (Triacontane (TC), Stearic acid (SA), and Behenyl Lignocerate (BL)) were studied individually, in pairs, or all together to make an oleogel using triolein as the oil. WAXS, SAXS and USAXS were used to elucidate the solid structures from angstroms to a few micrometers. A two-dimensional mapping of atomic positions for each molecule was carried out to understand the crystalline multilayer structures formed. We assumed that the molecules were rigidly extended and that they underwent no significant (hindered) rotations so that the free energy is determined by the Lennard-Jones interactions of closely packed multilayers. TC molecules were predicted to form a tilt angle of , yielding a SAXS line at Å─1, in acceptable agreement with the measured . For SA crystals (predicted) yielding a SAXS line at compared to (observed). No mixed crystals were observed for any pair of molecules or when all three were used. USAXS data showed that SA forms large nanocrystals compared to TC and BL. All three combinations of molecular pairs showed basic scatterers smaller or similar to those of individual molecules. The theory presented here, together with the experimental results, showed why no mixed crystals are formed from two or all three molecules. Data from the USAXS region suggested that, when using all three molecules, a more compact fractal structure was obtained, compared with those if one or two of the molecules were used. 相似文献
8.
Piyawan Krisanangkura Supathra Lilitchan Kornkanok Aryusuk Kanit Krisnangkura 《Journal of the American Oil Chemists' Society》2019,96(1):3-14
In this study, the molecular compressibility (km) of a fatty-acid methyl ester (FAME) or a biodiesel is correlated with ΔG, , via the Gibbs energy additivity method, where MW is the molecular weight of the FAME or the average MW of the biodiesel. The Gibbs energy associated with molecular compressibility () is further correlated with the structure of FAME. Thus, the relationship between the structure (of a FAME or a biodiesel) and the physical property (km) is established. Thus, km of a FAME at different temperatures can be easily estimated from the carbon numbers of fatty acid (z) and the number of double bonds (nd) with good accuracy. For biodiesel, km is calculated from the same equation with the average z (z(ave)) and average nd (nd(ave)). km is not temperature independent and a slight change in km depends on the structure of the FAME and biodiesel. For FAME having 14 carbon atoms or less in the fatty acid, km decreases as temperature is increased. On the other hand, for FAME with a longer chain length (16 or higher), km increases as temperature is increased. Similarly, a double bond in the long-chain FAME is more sensitive to temperature than the saturated FAME. 相似文献
9.
Measurements of Singlet Oxygen‐Quenching Activity of Vitamin E Homologs and Palm Oil and Soybean Extracts in a Micellar Solution
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Kazuo Mukai Eri Ishikawa Aya Ouchi Shin‐ichi Nagaoka Koichi Abe Tomomi Suzuki Katsuhiro Izumisawa 《Lipids》2018,53(6):601-613
Recently, a new assay method that can quantify the singlet oxygen‐absorption capacity (SOAC) of antioxidants (AO) and food extracts in homogeneous organic solvents has been proposed. In the present study, second‐order rate constants (kQ) for the reaction of singlet oxygen (1O2) with vitamin E homologs (α‐, β‐, γ‐, and δ‐tocopherols [Toc] and α‐, β‐, γ‐, and δ‐tocotrienols [Toc‐3]) were measured in an aqueous Triton X‐100 (5.0 wt%) micellar solution (pH 7.4). Toc‐3 showed kQ values larger than those of Toc in a micellar solution, although Toc and Toc‐3 showed the same kQ values in a homogeneous solution. Similar measurements were performed for 5 palm oil extracts 1–5 and one soybean extract 6, which contained different concentrations of Toc, Toc‐3, and carotenoids. It has been clarified that the 1O2‐quenching rates (kQ) (that is, the relative SOAC value) obtained for extracts 3–6 may be explained as the sum of the product of the rate constant () and the concentration ([AO‐i]/100) of AO‐i contained. The UV–vis absorption spectra of Toc and Toc‐3 were measured in a micellar solution and chloroform. The results obtained demonstrated that the kQ values of AO in homogeneous and heterogeneous solutions vary notably depending on (1) polarity (dielectric constant [ε]) of the reaction field between 1O2 and AO, (2) the local concentration of AO, and (3) the mobility of AO in solution. The results suggest that the SOAC method is applicable to the measurement of 1O2‐quenching activity of general food extracts in a heterogeneous micellar solution. 相似文献
10.
Grigor B. Bantchev Steven C. Cermak Amber L. Durham Neil P. J. Price 《Journal of the American Oil Chemists' Society》2019,96(4):365-380
Using the universal calibration and the Mark-Houwink equation (MHE) (), three batches of oleic estolide acids and their corresponding 2-ethylhexyl esters were characterized using gel permeation chromatography (GPC). The MHE parameters in tetrahydrofuran (THF) at 40 °C were determined (for acids: α = 0.442 ± 0.003 and log10K =2.505 ± 0.007, for esters: α =0.531 ± 0.006 and log10K =2.794 ± 0.018). The fits of the GPC chromatograms yielded also the oligomeric composition of the estolides, which can be used to calculate the estolide number (EN) of an estolide mixture, and other molecular-weight distribution parameters, such as number-average molecular weight (Mn ), weight-average molecular weight (Mw ), and dispersity (Ð). Using the Deming line fit, we concluded that the GPC should be expected to be approximately three times more sensitive than the currently used methods for determination of EN values. 相似文献
11.
12.
In the experimental countercurrent extraction of flaked cottonseed meats by trichloroethylene the residual oil content of the extracted flakes decreased with: first, a decrease in the final oil content of the final miscella; second, decrease in the flake moisture down to 8.64%; third, decrease in flake thickness; fourth, increase in temperature; and fifth, increase in extraction time. For the batch of cottonseed meats used the following equation was developed: whereR is percent residual extractables,b is flake thickness in feet,D is meat diameter in feet,ϑ is extraction time in hours,μ in viscosity, lb. per ft. hr.,ρ is density, lb. per cu. ft., andt is extraction temperature in degrees F. Not enough data were secured by extraction with hexane to check the equation developed for trichloroethylene extraction. Hexane is a poorer solvent for cottonseed oil than trichloroethylene. The amount of oil remaining in the meal is affected to a greater extent by the miscella concentration in hexane extraction than in trichloroethylene extraction. 相似文献
13.
The kinetics of isothermal nicotinamide release from poly(acrylic‐co‐methacrylic acid) loaded xerogel
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Tatjana Djajic Jelena Jovanovic Biljana Potkonjak Borivoj Adnadjevic 《Polymer Engineering and Science》2015,55(1):60-69
The isothermal kinetics of in vitro nicotinamide release from poly(acrylic‐co‐methacrylic acid) loaded xerogel into water was evaluated. The isothermal kinetics curves of nicotinamide release from poly(acrylic‐co‐methacrylic acid) xerogel were measured at different temperatures ranging from 296 K to 315 K. It was proven that the kinetics of nicotinamide release from poly(acrylic‐co‐methacrylic acid) xerogel was a kinetically complex process which was neither controlled by the processes of drug diffusion nor with the relaxation of the xerogel. The kinetic of nicotinamide release from poly(acrylic‐co‐methacrylic acid) may be described by the kinetics model of reversible first order chemical reaction and the apparent activation energy have value of Ea,M = 14.1 kJ mol?1 and preexponential factor ln(AM min?1) = 2.3. The rate constants of nicotinamide release ( ) and the rate constants of its reversible absorption reaction ( ) were calculated and found to fall within the range 0.019 min?1?0.033 min?1 for and 0.014 min?1?0.016 min?1 for . The value of activation energy for the nicotinamide releas, Ea.R =21.25 kJ mol?1, is significantly higher than the value for the process of nicotinamide absorption (Ea,A = 2.6 kJ mol?1). The rate of nicotinamide release was predetermined with the rate of nicotinamide molecules distribution between the hydrogel and surrounding solution. POLYM. ENG. SCI., 55:60–69, 2015. © 2014 Society of Plastics Engineers 相似文献
14.
Edward Eagle H. F. Bialek D. L. Davies J. W. Bremer 《Journal of the American Oil Chemists' Society》1954,31(4):121-124
In a series of four tests in which three deliberately chosen toxic cottonseed meals were treated with aqueous solutions of salts and alkalies, it was found that the best detoxifying effect was obtained with sodium hydroxide, followed very closely by potassium and ammonium hydroxides. Dry heat treatment alone did not detoxify, and mortality was high. Treatment with moisture plus heat gave partial detoxification. Of the 22 chemically-treated cottonseed meal samples tested, those treated with alkalies showed the best weight gains, the order of decreasing effectiveness being The residual toxicity of treated cottonseed meals cannot be explained on the basis of their free gossypol content as analyzed for meals with high values gave better growth performance than some with lower levels of free gossypol. There were also very marked differences in final body weight after 8 weeks of feeding six different treated cottonseed meal samples having practically the same free gossypol content. 相似文献
15.
Federico Rossi Raffaele Cucciniello Adriano Intiso Antonio Proto Oriana Motta Nadia Marchettini 《American Institute of Chemical Engineers》2015,61(10):3511-3515
Trichloroethylene (TCE) is a halogenated aliphatic organic compound frequently detected as pollutant in soils and ground water. To study the fate of TCE in water and to devise effective remediation strategies, a series of advection‐diffusion (dispersion) models, where the diffusion coefficient of TCE (DTCE) is an important parameter, have been developed. However, DTCE in water has never been experimentally determined and only theoretical values ( cm2 s?1 at 25°C) are present in the literature. A new method based on the Taylor dispersion technique, which allows to measure DTCE in a broad range of temperature and, in principle, in any solvent is presented. At 25°C DTCE = cm2 s?1 and the value increases almost linearly with the temperature, while, in the limit of the experimental error, is independent from [TCE] for dilute solutions. From the temperature dependence of DTCE, it was possible to calculate the specific TCE fitting constant in the well‐known Wilke and Chang theoretical relation and the activation energy of the diffusion process through the Arrhenius plot. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3511–3515, 2015 相似文献
16.
Ruchir M. Agrawal Michael J. Miller Vijay Singh Hans H. Stein Pawan S. Takhar 《Journal of the American Oil Chemists' Society》2022,99(5):379-391
There is a need to effectively concentrate soy protein from defatted soy flour (DSF) while simultaneously valorizing the carbohydrate-rich byproduct, which would otherwise be a waste. This study aims to evaluate a process developed to produce soy protein concentrates (SPC) by substantially hydrolyzing carbohydrates from DSF with the help of enzymes into water-soluble saccharides and monomeric sugars, which were simultaneously utilized by Saccharomyces cerevisiae for fermentation into ethanol. The enzyme mixture consisted of cellulase, pectinase, and -galactosidase blend. The effect of process time on SPC, overall protein recovery, carbohydrate hydrolysis, yeast growth, ethanol concentration, and total polyphenol concentration (TPC) of SPC and hydrolysate was evaluated. Control and enzymes-only (EO) systems were maintained in conjunction with the enzymes + yeast (EY) system to individually assess the impact of isoelectric precipitation of soy proteins and enzymatic hydrolysis of carbohydrates without yeasts. After 12.25 h of EY process, 100 g of dry DSF produced 68.45 g dry SPC containing % protein and 384 ml hydrolysate containing mg/ml ethanol. Flatulence-causing raffinose-series-oligosaccharides (RSOs) were completely hydrolyzed. Soluble carbohydrates in the EY treatment were consistently lower than in the control and EO treatment. TPC of SPC prepared by EY treatment increased by 2.5 times compared to the control. Thus, this novel process successfully produced a high-protein SPC with hydrolyzed RSOs, lower insoluble carbohydrates, high TPC, and a coproduct ethanol. 相似文献
17.
Novel Fe/MnK‐CNTs nanocomposites as catalysts for direct production of lower olefins from syngas
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Di Wang Jian Ji Bingxu Chen Wenyao Chen Gang Qian Xuezhi Duan Xinggui Zhou Anders Holmen De Chen John C. Walmsley 《American Institute of Chemical Engineers》2017,63(1):154-161
Novel Fe/MnK‐CNTs nanocomposites are developed as catalysts for direct production of lower olefins from syngas, delivering a high iron time yield of 337.2 μmolCO· ·s?1 with 51.3%C selectivity toward C2?C4 olefins under the optimal reaction conditions (270°C, 2.0 MPa, 30,000 mL h?1 ). These catalysts are optimized by varying calcination temperature from 150 to 400°C. Multiple techniques including transmission electron microscopy, Elemental mapping, X‐ray diffraction, X‐ray photoelectron spectroscopy, H2‐temperature‐programmed reduction, and Raman were employed to reveal the relationship between the catalyst nature and unique catalytic behavior. In particular, the resultant catalyst from the calcination temperature of 220°C exhibits the highest selectivity of C2?C4 olefins as well as good stability, which are enabled by the trade‐off among the effects of iron particle sizes, promoters, metal‐support interaction and support surface chemistry. Moreover, influences of reaction temperature, reaction pressure and space velocity are also investigated. © 2016 American Institute of Chemical Engineers AIChE J, 63: 154–161, 2017 相似文献
18.
High‐resolution synchrotron powder X‐ray diffraction (XRD) experiments were conducted to clarify the transformation of sillimanite to mullite (mullitization) and determine the mullitization temperature (Tc). We were able to distinguish sillimanite and mullite in the XRD patterns, despite their very similar crystallographic parameters, and to detect the appearance of small mullite peaks among sillimanite peaks. Analysis of the Johnson‐Mehl‐Avrami (JMA) equation for mullitization ratio (ζ) revealed that at temperatures T≥1240°C the mullitization had the same kinetics. The activation energy E at T≥1240°C obtained from the Arrhenius plot was 679.8 kJ mol?1. In analysis using a time‐temperature‐transformation diagram for mullitization, a mullitization curve of ζ=1% can be described as where t is time, n is a reaction‐mechanism‐dependent parameter determined as 0.324 by JMA‐analysis, k0 is the frequency factor, EA is the activation energy for atomic diffusion, and represents the activation energy for nucleation. The results of fitting the data to this equation were Tc=1199°C, A=3.9×106 kJ mol?1 K?2, EA=605 kJ mol?1, and k0=3.65×1015. We conclude that the boundary between sillimanite and mullite+SiO2 in the phase diagram is ~1200°C. 相似文献
19.
Jolanta Koliska Aleksandra Grzelakowska Jolanta Sokoowska 《Coloration Technology》2019,135(6):501-509
The sensing properties of dyes based on 2(1H) quinolones containing dicyanoethylene groups towards selected anions such as CN?, F?, I?, Cl?, SCN?, CH3COO?, and were evaluated. The spectroscopic responses of these compounds were investigated in a solution of acetonitrile/water (1:9, v/v) and phosphate buffer at a pH of 7.4. These dyes were found to act as efficient colorimetric and high turn–off fluorescent sensors to cyanide anions. The fluorescence intensity was linearly related to the concentration of CN? from 1 to 10 µmol/L, and the detection limits reached a micromolar level of 6.7, 11.1, 3.8 and 7.2 µmol/L for 1‐4 , respectively. The cytotoxic effect of the dyes against human neuroblastoma cells (SH‐SY5Y) was also determined by MTT assay. The examined compounds exhibited slight cytotoxicity against cells under experimental conditions. 相似文献
20.
Michiel M. de Beer Jos T. F. Keurentjes Jaap C. Schouten John van der Schaaf 《American Institute of Chemical Engineers》2016,62(10):3784-3796
Centrifugal intensification of condensation heat transfer in the rotor–stator cavities of a stator–rotor–stator spinning disc reactor (srs‐SDR) is studied, as a function of rotational velocity ω, volumetric throughflow rate , and average temperature driving force . For the current range of ω, heat transfer from the vapor bubbles to the condensate liquid is limiting, due to a relatively low gas–liquid interfacial area aGL. For rad s?1, a strong increase of aGL, results in increasing the reactor‐average condensation heat transfer coefficient hc from 1600 to 5600 W m?2 K?1, for condensation of pure dichloromethane vapor. Condensation heat transfer in the srs‐SDR is enhanced by rotation, independent of the vapor velocity. The intensified condensation comes at the cost of relatively high energy dissipation rates, indicating condensation in the srs‐SDR is more suited as a means to supply heat (e.g. in an intensified reactor‐heat exchanger), rather than for bulk cooling purposes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3784–3796, 2016 相似文献