Journal of the American Oil Chemists Society最新文献

α-Tocopherol (α-TOC) and myricetin (MYR) synergistically inhibit lipid oxidation in bulk oil but the mechanism underlying this effect is unknown. In this research, stripped soybean oil (SSO) was treated with α-tocopherol (50 μM), myricetin (10–250 μM), and their combinations. Taxifolin (TAX) was also tested because it has structural similarities to myricetin but with a higher redox potential. α-Tocopherol: myricetin ratios of 5:1, 2:1, 1:1, 1:2, and 1:5 resulted in extended lag phases ranging from 16 to 99 days, with lag phase increasing with increasing myricetin concentrations. Synergism between α-tocopherol and myricetin was also observed in phospholipid-containing bulk oils both in the absence and presence of reverse micelles, although the reverse micelles shortened the lag phases. Myricetin (redox potential = 360 mV) delayed the oxidation of α-tocopherol (redox potential = 500 mV) whereas taxifolin (redox potential = 500 mV) did not. Both myricetin and taxifolin were able to chelate iron as determined by UV–VIS spectroscopy. These results suggested that the lower redox potential of myricetin allowed it to produce synergistic antioxidant activity potentially by regenerating oxidized α-tocopherol and through its ability to decrease oxidation by metal chelation.

The organometallics like ZDDPs are widely used as multifunctional additives in lubricants for imparting antiwear, antioxidant, and corrosion inhibitor activity. Since it has toxic elements like P, Zn, and S so it is an environmentally toxic, non-biodegradable, and ash-forming additive. In automotive emissions, it also causes poisoning in catalytic converters. Due to environmental concerns, it is an issue of awareness to discover less toxic alternatives for these multifunctional additives despite their potent and economical properties. In this work, MO was reacted in a stoichiometric ratio with Tga, giving the intermediate compound MO-Tga through thiol-ene coupling. Subsequently, the reaction of MO-Tga with PPA gave a novel multifunctional additive MO-Tga-PPA. The molecular characteristics and thermal stability of MO-Tga-PPA were studied using techniques like NMR, FTIR, and TGA. The additive was doped at various concentrations such as 1000, 2000, 3000, 4000, and 5000 ppm in polyol to examine their antiwear, antifriction, antioxidant, and anticorrosion performance. It reveals the maximum reduction of 53.85% in the average COF and 25.51% in AWSD at 5000 ppm. The antioxidant activity shows a maximum free radicals inhibition of 97.9% at 3000 ppm using the DPPH. As far as the anticorrosion activity is concerned, the values for the penetration rate, corrosion rate, and weight loss were reduced to 0.015 mpy, 0.082 mdd, and 0.08 mg from the observed values of 0.114 mpy, 0.62 mdd, and 0.60 mg in polyol base oil was observed at 4000 ppm.

Mango (Mangifera indica L.) seeds is an interesting source of fat, rich in stearic (St) and oleic (O) acid with three major triacylglycerols (TAG): StOSt, StOO, and StLSt. The kernel fat content and quality depend however on the varieties and their origin. The objective of this study was to investigate the crystallization and polymorphic behavior of mango kernel fat extracted from three selected Ivorian varieties which differ in terms of TAG composition: Kent (KT), Djakoumankoun (DN) and Brooks (BR). The isothermal crystallization behavior was examined at 15 and 20°C by pulsed nuclear magnetic resonance, differential scanning calorimetry, x-ray diffraction (XRD) and polarized light microscope. Under static conditions, DN crystallized faster, followed by BR, then KT. At 15°C, an unusual evolution was observed for both DN and BR, which can be explained by a melt-mediated polymorphic transition from α into more stable forms. Using a differential scanning calorimetry (DSC) stop-and-return technique, different crystallization behaviors were also observed. Isothermal XRD experiments confirmed that the kinetics of the polymorphic transformation was different within the three samples, even if the three fats were β-3L-tending. At 15°C, KT transformed from liquid state to stable form without passing through α-form, while DN and BR crystallized first into α-from which transformed further to β′, then into stable β-form. At 20°C, DN and BR crystallized directly from liquid to β′, which later transformed into β-form while KT did not crystallize under the same conditions. The huge differences observed result from the differences in the TAG profiles, mainly in the StOO and StOSt content.

Four Deep Eutectic Solvents (DES) based on choline chloride (ChCl) and different hydrogen bond donors (1,4-butanediol, glycerol, isosorbide, and urea) were tested as reaction medium for the immobilized Candida antarctica B (iCALB) lipase-catalyzed esterification of fatty acids with n-butanol. Although the strong hydrogen bonds between DES components were expected to lower their reactivity, all except urea, competed in the esterification reaction. To study the effect of acyl group donor and water, different chain length of saturated fatty acids (ranging from 6:0 to 18:0) and water content (ranging from 0, 1, 2 or 3 molar ratio of water/ChCl) were tested in the lipase-catalyzed esterification with n-butanol in ChCl:urea (1:2, molar ratio). When the incubation was performed in the absence of water, the shorter the fatty acid chain length, the higher the conversion. Upon water addition, a drastic increase in the esterification rate of all the fatty acids was observed and, conversely to what occurred in the anhydrous media, the longer the fatty acid chain length, the higher the conversion. Results suggest that water concentration in the DES medium possesses a multifactorial effect, as it influences the enzyme activity, the solvent viscosity, the DES structure, and the interaction between DES components, substrates, and enzymes, thus determining the efficiency and yield of the esterification reaction.

The effects of the agitation conditions and headspace-to-emulsion volume ratio on lipid oxidation in emulsions can be considerable, but have not been systematically investigated yet. In the current paper, lipid oxidation was monitored in model oil-in-water (O/W) emulsions at pH 4.0 and 25°C in the presence of 200 μM iron sulfate. The formation of primary (conjugated dienes and hydroperoxides) and secondary (p-anisidine value and TBARS) oxidation products confirmed that using rotating or shaking devices doubled the rate of oxidation product formation compared to a non-agitated system, as a result of enhanced oxygen transfer. Furthermore, we found that a higher headspace-to-emulsion volume ratio at least doubled the rate of lipid oxidation due to a higher amount of oxygen available per mass of oil, which is in agreement with the kinetics of the reaction. This indicates that the variation in literature data on lipid oxidation in emulsions can be attributed to differences in mixing conditions and volume ratios. These factors are crucial and should be reported systematically along with the agitation conditions, and sampling method. This will enable a better comparison of literature information.

Protein foams are common to foods, such as meringue, whipped cream and mousses. Stability is a challenging issue determined by fat and sugar content. We hypothesize that acetyl-triacylglycerols (acetyl-TAG) that possess sn-3 acetate group with high oleic content can provide stability to the foam at reduced sugar concentrations by increasing the surface viscosity and minimizing serum drainage. A fractional factorial Box-Wilson design was used to investigate the effects of whey protein concentration (WPI) (2–10 wt%), sucrose concentration (SC) (10–30 wt%) and acetyl-TAG concentration (ATC) (0–1 wt%) on overrun (FO), stability against serum drainage (FD) and surface dilatational rheology. Each response was analyzed by linear regression model fitting and a backward elimination algorithm for significance (α = 0.01). FO was significantly affected (p < 0.01) by WPI and ATC, but not sucrose concentration. The optimum overrun (nearly 700%) was obtained at 9 wt% WPI and 0.6 wt% ATC. Drainage and viscoelastic properties were significantly (p < 0.01) affected by all process variables. Dynamic complex modulus (|E|) as measured using an optical tensiometer was around 30–40 mN/m when acetyl-TAG was higher than 0.5 wt%. Our findings indicated that the acetyl-TAG can be used to enhance the stability of protein foams in reduced sugar food products, however, not at high sugar concentrations (30 wt%).

The triacylglycerols (TAGs) containing saturated (S_at)-unsaturated (U) fatty acid moieties (S_at-U mixed acid TAGs) are widely present in most natural fats and employed in many industrial applications. The mixing behavior of different Sat-U mixed acid TAGs acts important roles in the physicochemical properties TAG-based materials. Among the three main mixing states of miscible, eutectic and molecular compound (MC) forming mixtures, fundamental research has been conducted on the MC crystals formed by different S_at-U mixed acid TAGs to understand the structures, phase behavior and crystallization properties. This article reviews studies to date on the complex thermodynamic, kinetic and structural factors that affect the formation of MC crystals in binary and ternary mixtures of S_at-U mixed acid TAGs (S_atUS_at, S_atS_atU, US_atU and UUS_at) through specific molecular interactions among the component TAGs. Furthermore, the application of the MC-forming mixtures containing cacao butter to new types of cocoa butter alternative is reviewed.

Vegetables including asparagus contain a wide range of fatty acids, mainly stored in triacylglycerols. One class of interesting minor fatty acids is the family of furan fatty acids (FuFAs) because of their antioxidant properties. Since FuFAs have not been studied previously in asparagus (Asparagus officinalis L.), we developed and applied a simplified method for their analysis in 20 fresh and three preserved samples. Four FuFAs were detected with clear dominance of the dimethyl-substituted FuFAs (D-FuFAs) 11D5 and 9D5 as well as small amounts of the monomethyl-substituted FuFAs (M-FuFAs) 11M5 and 9M5. The total amounts of FuFAs in fresh white asparagus ranged from 1.4 to 4.6 mg/100 g dry weight (mean 3.0 mg/100 g dry weight). Subsequent LC-Q-Orbitrap-HRMS measurements enabled the detection of 22 different FuFA-containing TAGs. These were predominantly found together with one or two polyunsaturated fatty acid.