Extraction of Phospholipids from Structured Dry Egg Yolk

Chicken egg yolk is a concentrated source of phospholipids (PL). Extracting egg PL with high efficiency is vital to the availability and economics of this high-valued lipid product. In this study, two types of structured dry egg yolk materials, yolk flakes and pellets, were prepared. Two commonly used solvents, hexane and ethanol, were tested on the extraction of total yolk lipids including the PL. The PL fraction was obtained by the conventional cold acetone precipitation. The drum-dried yolk flakes were shown to be an ideal starting material for total lipid and PL extraction. Anhydrous ethanol can extract almost all the neutral lipids and PL with little change to the individual components of the native PL. A PL product with a purity of more than 90 % and a yield of 99 % can be prepared using this method.     

Fatty acid composition of the adipose tissue and yolk lipids of a bird with a marine-based diet, the emperor penguin (Aptenodytes forsteri)

The emperor penguin (Aptenodytes forsteri) is an Antarctic seabird feeding mainly on fish and therefore has a high dietary intake of n-3 polyunsaturated fatty acids. The yolk is accumulated in the developing oocyte while the females are fasting, and a large proportion of the fatty acid components of the yolk lipids are derived by mobilization from the female's adipose tissue. The fatty acid composition of the total lipid of the yolk was characterized by high levels of n-3 polyunsaturated fatty acids. However, it differed in several respects from that of the maternal adipose tissue. For example, the proportions of 14∶0, 16∶1n−7, 20∶1n−9, 22∶1n−9, 20∶5n−3, and 22∶6n−3 were significantly greater in adipose tissue than in yolk. Thus adipose tissue lipids contained 7.6±0.3% and 8.0±0.3% (wt% of total fatty acids; mean ±SE; n=5) of 20∶5n−3 and 22∶6n−3, respectively, whereas the yolk total lipid contained 1.6±0.1 and 5.5±0.3% of these respective fatty acids. The proportions of 16∶0, 18∶0, 18∶1n−9, 18∶2n−6, and 20∶4n−6 were significantly lower in the adipose tissue than in the yolk lipids. The proportions of triacylglycerol, phospholipid, free cholesterol, and cholesteryl ester in the yolk lipid were, respectively, 67.0±0.2, 25.4±0.3, 5.3±0.2, and 1.8±0.2% (wt% of total yolk lipid). The proportions of 20∶4n−6, 20∶5n−3, 22∶5n−3, and 22∶6n−3 were, respectively, 5.7±0.3, 2.8±0.2, 1.4±0.1, and 11.7±0.5% in phospholipid and 0.4±0.0, 1.2±0.1, 0.8±0.1 and 3.6±0.3% in triacylglycerol. About 95% of the total vitamin E in the yolks was in the form of α-tocopherol with γ-tocopherol forming the remainder. Two species of carotenoids, one identified as lutein, were present.     

Fractionation of tallow fatty acids. Preparation of purified oleic acid and an inedible olive oil substitute

Summary Tallow fatty acids have been fractionally crystallized from acetone at temperatures ranging from 0° to −60° C. By crystallizing at 0° to −20° C., a saturated acid fraction which amounts to 40 to 50% by weight of the starting material has been obtained. This fraction corresponds to “double- or triple-pressed stearic acid.” The filtrate acids from the crystallization at −20° C. contain over 90% of the oleic acid present in the starting material, and in fatty acid composition this mixture is similar to olive oil. From this fraction. which amounts to about 50% by weight of the starting material, a synthetic triglyceride with, properties approximating those of olive oil has been prepared. By low-temperature crystallization of this oleic-acid-rich fraction at −50° to −60° C., followed by fractional distillation, a good yield of purified oleic acid (oleic acid content, over 95%) has been obtained. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, United States Department of Agriculture.     

Increase in the γ-linolenic acid content by solvent winterization of fungal oil extracted fromMortierella genus

The fungal oil extracted fromMortierella ramanniana var.angulispora (IFO 8187) was solvent winterized in order to raise the content of γ-linolenic acid (GLA). Effects of winterization conditions (solvent, oil concentration in the solvent and temperature) and changes of glyceride compositions were discussed. The fungal oil was separated into four diglycerides and 17 triglycerides (TG) with high performance liquid chromatography. The predominant species were POO, POP and LOP, whose contents were 24.4, 22.9 and 9.4% of the total TG, respectively. Ethanol at 4°C gave the highest GLA content of 10.5% in spite of lower yield than with acetone at −20°C. The highest separation efficiency for GLA (η_GLA) was 0.27 with acetone at −20°C and 10% oil concentration, resulting in 8.3% of GLA from the fungal oil at 5.7% LGA. In case of lower oil concentration at 5–20%, η_GLA showed higher in the following order: acetone (−20°C)>n-hexane (−20°C)>acetone (4°C)>petroleum ether (−20°C). The winterization process also proved to be effective for the separation of TG type, Sa₂U (Sa; saturated fatty acid; U, unsaturated fatty acid) into the crystallized fraction and SaU₂ into the liquid fraction. Acetone at −20°C showed higher separation efficiency for triunsaturated TG than the other solvents.     

Extraction of phospholipids from structured dry chicken egg

Chicken egg contains a high level of phospholipids (PL) in the yolk. Recovering yolk total lipids and extracting egg PL with efficiency are important to the availability and utilization of these health‐promoting lipid products. In this study, we prepared two structured dry egg yolk materials and used two common solvents to extract and concentrate the PL. We found that drum‐dried flake‐like yolk is an ideal starting material for lipid extraction. Anhydrous ethanol can extract almost all the neutral lipids and PL. PL with purity over 90% can be prepared by cold acetone precipitation from the total lipids.     

New preparation of pure petroselinic acid from fennel oil (Foeniculum vulgare)

Pure petroselinic acid (cis-6-octadecenoic acid) has been isolated from fennel oil by acid soap crystallization at 4°C in methanol, followed by two urea segregations at room temperature and crystallization at −30°C in acetone. The purity control of petroselinic acid was effected by combined gas chromatography, and¹³C nuclear magnetic resonance. This petroselinic acid preparation was compared to other previous crystallization or enzymatic methods, showing that this method is both short (four steps) and easy to apply.     

Supercritical CO2 extraction of egg yolk: Impact of temperature and entrainer on residual protein

Differential scanning calorimetry (DSC) was used to monitor changes in protein conformation resulting from supercritical carbon dioxide (SC-CO₂) extraction of lipids from egg yolk. Extraction temperatures of 65°C and lower had no effect on protein conformation as indicated by similar denaturation temperatures and enthalpies of denaturation (ΔH). An extraction temperature of 75°C resulted in a reduction in the ΔH value for ovalbumin present in the egg yolk. The use of 3% methanol as an entrainer during extraction at 36 MPa and 40°C resulted in a 50% reduction in the ΔH value for ovalbumin. The use of high temperatures and/or entrainers during SC-CO₂ extraction can result in significant protein denaturation.     

DSC and synchrotron-radiation X-ray diffraction studies on crystallization and polymorphic behavior of palm stearin in bulk and oil-in-water emulsion states

The crystallization and polymorphic behavior of palm stearin (PS) in a bulk state and in oil-in-water (O/W) emulsion droplets (average diameter, 1.7±0.3 μm) was observed by using DSC, optical microscopy, and in situ X-ray diffraction with synchrotron radiation (SR-XRD). For the bulk sample the DSC measurements revealed three main exothermic peaks at approximately 31 (large), 21 (small) and 3°C (medium) on cooling, and broad endothermic peaks at approximate −3 (small), 8, 15 to 25 (medium), and 37 and 53°C upon heating. The SR-XRD patterns taken during cooling from 60 to −5°C clarified that the DSC exothermic peaks around 31 and 3°C corresponded to crystallization of the α form of high-melting and low-melting fractions, respectively, and that the occurrence of β′ corresponded to the small exothermic peak around 21°C. The XR-XRD patterns taken during heating from −5 to 60°C demonstrated that the DSC endothermic peaks corresponded to the following transformation processes: melting of α of the low-melting fraction (−3°C), melt-mediated transformation from α to ∇′ (15–25°C), melting of β′ (36°C), and melting of β (53°C) of the high-melting fraction. As for the O/W emulsion sample, the DSC and SR-XRD measurements during the cooling and heating processes exhibited basically the same behavior as that of PS in the bulk state, except that β′ did not crystallize during the cooling process, and the temperatures of crystallization of α, melt-mediated α→β′→β transformation, and melting of β were lower in the emulsion droplets than in the bulk state.     

Modification of vegetable oils

Summary 1. An investigation has been made of low-temperature crystallization from organic solvents as a means of effecting practical separations of the solid and liquid acids of unhydrogenated and hydrogenated cottonseed oils. 2. At any fixed temperature the most efficient separations were obtained in the highly polar solvents, acetone and methyl acetate. However, it was possible in any case to make nonpolar petroleum naphtha (Skellysolve B) fully equivalent to the polar solvents simply by conducting the crystallization at a temperature approximately 10° F. lower than that employed with the polar solvents. Ethyl acetate and methyl ethyl ketone were intermediate between petroleum naphtha and acetone or methyl acetate in their effectiveness. 3. By employing a solvent-fatty acid ratio of 4 to 1 by weight and conducting crystallizations at 5° F. or lower from acetone and −5° F. or lower from petroleum naphtha, the liquid fatty acids from unhydrogenated cottonseed oil could be reduced to below −2° C. in titer and to below about 3 per cent in saturated acid content. Under these conditions there was no appreciable crystallization of oleic acid. 4. At a solvent-fatty acid ratio of 6 to 1 and the same temperatures (5° F. for acetone and − 5° F. for petroleum naphtha) equally good separations could be made of the saturated fatty acids present in the mixed acids from hydrogenated cottonseed oil (I.V.=70). Separation of “iso-oleic” acids from the fatty acids of the hydrogenated oil took place over a wide range of temperatures, beginning at 35° F. in acetone and at 25° F. in petroleum naptha, and being incomplete (according to Twitchell analyses of the liquid acids) in either solvent at −15° F. However, the bulk of the higher melting iso-oleic acids was precipitated as the temperature approached −5° F. in acetone and −15° F. in petroleum naphtha. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

Lipase-Catalyzed Synthesis of Saccharide–Fatty Acid Esters Using Suspensions of Saccharide Crystals in Solvent-Free Media

Saccharide–fatty acid esters, important biobased and biodegradable emulsifiers in foods, cosmetics, and pharmaceuticals, were produced with high yields and productivity via immobilized Rhizomucor miehei lipase-catalyzed esterification in solvent-free systems at 65 °C. Preliminary experiments demonstrated high rates of reaction occurred in the presence of acetone near or above its boiling point, due to the formation of 10–200 μm suspensions of saccharide particles. Subsequently, a two-step process was developed to produce a solvent-free supersaturated solution of 1.5–2.0 wt% saccharide that remained stable for ≥10–12 h. The solvent-free suspensions were used in a bioreactor system at 65 °C, consisting of a reservoir open to the atmosphere that contained molecular sieves, a peristaltic pump, and a packed bed bioreactor, operated under continuous recirculation. At 10 h intervals, suspensions were re-formed by treating the substrate/product mixture with additional acyl acceptor and applying strong agitation. Using this system and approach, a product mixture containing 88% fructose oleate was formed, of which 92% was monoester, within 6 days. This equates to a productivity of 0.2 mmol h⁻¹ g⁻¹, which is similar to values reported for synthesis in the presence of solvent.     

Comparison of the electrochemical properties of intermediate temperature solid oxide fuel cells based on protonic and anionic electrolytes

The physico-chemical properties of two protonic electrolytes BaCe_0.8Y_0.2O_3-δ and BaCe_0.9Y_0.1O_3-δ were investigated. The BaCe_0.8Y_0.2O_3-δ electrolyte showed better crystallographic purity and lower amount of carbonate phase on the surface. A comparison between the BaCe_0.8Y_0.2O_3-δ protonic electrolyte supported cell and an anionic (Ce_0.8Gd_0.2O_1.95) one was made. The maximum power densities (IR-free) of 183 mW cm⁻² and 400 mW cm⁻² were obtained in H₂ (R.H. 3%) at 700 °C, for the protonic and anionic electrolyte based cells, respectively.     

Autoxidation of methyl linoleate initiated by the ozonide of allylbenzene

Allylbenzene ozonide (ABO), a model for polyunsaturated fatty acid (PUFA) ozonides, initiates the autoxidation of methyl linoleate (18∶2 ME) at 37°C under 760 torr of oxygen. This process is inhibited by d-α-tocopherol (α-T) and 2,6-di-ert-butyl-4-methylphenol (BHT). The autoxidation was followed by the appearance of conjugated diene (CD), as well as by oxygen-uptake. The rates of autoxidation are proportional to the square root of ABO concentration, implying that the usual free radical autoxidation rate law is obeyed. Activation parameters for the thermal decomposition of ABO were determined under N₂ in the presence of radical scavengers and found to be E_a=28.2 ±0.3 kcal mol⁻¹ and log A=13.6±0.2; k_d (37°C) is calculated to be (5.1±0.3)×10⁻⁷ sec⁻¹. Autoxidation data are also reported for ozonides of 18∶2 ME and methyl oleate (18∶1 ME).     

Thermal adaptation affects the fatty acid composition of plasma phospholipids in trout

The adaptive changes in the fatty acid (FA) composition of plasma phospholipids (PL) in response to alterations in environmental water temperature were investigated in juvenile rainbow trout (Oncorhynchus mykiss). The changes observed during thermal adaptation from 22°C in summer to 8°C in winter were reproduced by laboratory cold acclimation (CA) at 6°C of 22°C-summer-acclimated animals. In cold-acclimated and winter-acclimated trout, the increase in the unsaturation of PL fatty acids was mainly due to an enrichment of approximately 7% in the total weight percentage of 22∶6n−3, while a concomitant significant decrease in the levels of 18∶0 and of the monoenoic n−9 FA was observed. A time course study revealed that the changes in PL fatty acids became significant after 10 d of CA and were complete after one month. These changes in the composition of the fatty acyl chains of plasma total PL indicate that the FA composition of plasma lipoprotein PL does not remain constant during thermal adaptation. This would suggest that plasma lipoproteins provide a rapid systemic supply of lipids containing more or less unsaturated FA during thermal adaptation of poikilothermic animals.     

Photoelectrochemical characterization of the synthetic crednerite CuMnO<Subscript>2</Subscript>

High quality crednerite CuMnO₂ was prepared by solid state reaction at 950 °C under argon flow. The oxide crystallizes in a monoclinically distorted delafossite structure associated to the static Jahn–Teller (J–T) effect of Mn³⁺ ion. Thermal analysis showed that it converts reversibly to spinel Cu _x Mn_3−x O₄ at ~420 °C in air and further heating reform the crednerite above 940 °C. CuMnO₂ is p-type, narrow semiconductor band gap with a direct optical gap of 1.31 eV. It exhibits a long-term chemical stability in basic medium (KOH 0.5 M), the semi logarithmic plot gave an exchange current density of 0.2 μA cm⁻² and a corrosion potential of ~−0.1 V_SCE. The electrochemical oxygen insertion/desinsertion is evidenced from the intensity–potential characteristics. The flat band potential (V _fb = −0.26 V_SCE) and the holes density (N _A  = 5.12 × 10¹⁸ cm⁻³) were determined, respectively, by extrapolating the curve C ⁻² versus the potential to the intersection with C ⁻²  = 0 and from the slope of the Mott–Schottky plot. From photoelectrochemical measurements, the valence band formed from Cu-3d wave function is positioned at 5.24 ± 0.02 eV below vacuum. The Nyquist representation shows straight line in the high frequency range with an angle of 65° ascribed to Warburg impedance originating from oxygen intercalation and compatible with a system under mass transfer control. The electrochemical junction is modeled by an equivalent electrical circuit thanks to the Randles model.     

Differential uptake of cholesterol and plant sterols by rat erythrocytes in vitro

The in vitro uptake of radioactively labeled cholesterol and the plant sterol β-sitosterol has been examined in rat erythrocytes. From mixed micellar solutions containing egg yolk phospholipid and sodium taurocholate, the erythrocytes showed a nonlinear uptake of the two sterols. The uptake leveled off after about 45 min with the attainment of a 1∶1 total sterol-to-phospholipid ratio within the cell membrane, as determined on a mass basis. From soltuions containing egg yolk phospholipid, or purified egg yolk phosphatidylcholine, a preference for cholesterol over the plant sterol was observed, increasing with time from a cholesterol/β-sitosterol uptake ratio of unity (the media ratio) to a maximum of 2 after a 60-min incubation. Correction of the data for nonspecifically bound sterol increased the ratio to a maximum of 5 at the 30-min time point. The increase in the cholesterol/β-sitosterol uptake ratio with time, following an initial nonspecific association, showed that penetration of the plasma membrane by the sterol was required for the selectivity to be expressed. The presence of lysophosphatidylcholine or bovine serum albumin did not exert any noticeable influence over the extent of selectivity of absorption. Replacement of the egg yolk phospholipid with synthetic dipalmitoyl-phosphatidylcholine led to a loss of the sterol selectivity. No evidence was found to support a selective extraction of sterol from the erythrocyte membrane to account for the observed effects, nor was there any sign of a mass accumulation of phospholipid during the incubation. It is suggested that the media phospholipid influences the membrane permeability toward cholesterol and β-sitosterol. Presented in part at the 72nd annual meeting of the American Oil Chemists' Society, New Orleans, LA, May 1981.     

Additive manufacturing of continuous carbon fiber reinforced high entropy ceramic matrix composites via paper laminating,direct slurry writing,and precursor infiltration and pyrolysis

In this study, continuous carbon reinforced C_f/(Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C–SiC high entropy ceramic matrix composites were additively manufactured through paper laminating (PL), direct slurry writing (DSW), and precursor infiltration and pyrolysis (PIP). (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta_0.2)C high entropy ceramic (HEC) powders were synthesized by pressureless sintering and ball milling. A certain proportion of HEC powder, SiC powder, water, binder, and dispersant were mixed to prepare the HEC-SiC slurry. Meanwhile, BN coating was prepared on the 2D fiber cloth surface by the boric acid-urea method and then the cloth was cut into required shape. Additive manufacturing were conducted subsequently. Firstly, one piece of the as-treated carbon fiber cloth was auto-placed on the workbench by paper laminating (PL). Then, the HEC-SiC slurry was extruded onto the surface of the cloth by direct slurry writing (DSW). PL and DSW process were repeated, and a C_f/HEC-SiC preform was obtained after 3 cycles. At last, the preform was densified by precursor infiltration and pyrolysis (PIP) and the final C_f/HEC-SiC composite was prepared. The open porosity of the C_f/HEC-SiC composites, with the HEC volume fractions of 15, 30 and 45%, were 7.7, 10.6, and 11.3%, respectively. And the density of the C_f/HEC-SiC composites, with the HEC volume fractions of 15, 30 and 45%, were 2.9, 2.7 and 2.3 g/cm³, respectively. The mechanical properties of the C_f/HEC-SiC composites increased firstly and then decreased with the HEC content increase, reaching the maximum value when the HEC volume fraction was 30%. The mechanical properties of the C_f/HEC-SiC composites containing 45, 30 and 15% HEC were as follows: flexural strength (180.4 ± 14 MPa, 183.7 ± 4 MPa, and 173.9 ± 4 MPa), fracture toughness (11.9 ± 0.17 MPa m^1/2, 14.6 ± 2.89 MPa m^1/2, and 11.3 ± 1.88 MPa m^1/2), and tensile strength (71.5 ± 4.9 MPa, 98.4 ± 12.2 MPa, and 73.4 ± 8.5 MPa). From this study, the additive manufacturing of continuous carbon fiber reinforced high entropy ceramic matrix composites was achieved, opening a new insight into the manufacturing of ceramic matrix composites.     

Intravenous injection of tridihomo-γ-linolenoyl-glycerol into mice and its effects on delayed-type hypersensitivity

Highly purified tridihomo-γ-linolenoyl-glycerol (DGLA-TG) was emulsified with egg yolk lecithin as a 10% (wt/vol) DGLA-TG emulsion. We injected 0.05 or 0.5 mL of the emulsion into mice through the tail vein and investigated its effects on the fatty acid composition of spleen cells and on delayed-type hypersensitivity (DTH) response. At 1 h after the injection, dihomo-γ-linolenic acid (DGLA) concentrations were increased significantly in the total phospholipid fraction of spleen cells from 1.21±0.13 mol% to 2.09 ±0.74 mol% (P<0.02) and 7.95±1.25 mol% (P<0.001) in the 0.05-mL and 0.05-mL groups respectively. Mice, which had already been immunized with sheep red blood cells (SRBC), were challenged by the injection of SRBC into the right-hind footpad. Intravenous injection into mice with 0.5 mL of the emulsion immediately before the challenge almost completely suppressed DTH response measured by the swelling of the right-hind footpads 24 h thereafter. This inhibitory effect on the DTH response was significant with as little as 0.05 mL of the emulsion, whereas a soybean oil emulsion was not effective at all. In conclusion, intravenous injection of a DGLA emulsion increased DGLA concentrations in immune cells within 1 h and suppressed the DTH reaction.     

Polymeric ionic liquid membranes as electrolytes for lithium battery applications

A new kind of polymeric ionic liquid (PIL) membrane based on guanidinium ionic liquid (IL) with ester and alkyl groups was synthesized. On addition of guanidinium IL, lithium salt, and nano silica in the PIL, a gel PIL electrolyte was prepared. The chemical structure of the PIL and the properties of gel electrolytes were characterized. The ionic conductivity of the gel electrolyte was 5.07 × 10⁻⁶ and 1.92 × 10⁻⁴ S cm⁻¹ at 30 and 80 °C, respectively. The gel electrolyte had a low glass transition temperature (T _g ) under −60 °C and a high decomposition temperature of 310 °C. When the gel polymer electrolyte was used in the Li/LiFePO₄ cell, the cell delivered 142 mAh g⁻¹ after 40 cycles at the current rates of 0.1 C and 80 °C.     

Physical Properties and Fatty Acid Profiles of Oils from Black,Kidney, Great Northern,and Pinto Beans

Four common beans (black, kidney, great northern, and pinto) were extracted with hexane and found to contain about 2% triacylglycerols. The fatty acids in these bean oils were mainly linolenic (41.7–46 wt%), linoleic (24.1–33.4 wt%), palmitic (10.7–12.7 wt%) and oleic (5.2–9.5 wt%). Because of the high levels of polyunsaturated fatty acids, the bean oils had iodine values between 174 and 177 g/100 g (compared to 130 g/100 g for soybean oil). Yet, the bean oils exhibited high oxidative stability due to the presence of high amounts of tocopherols (2,670–2,970 ppm). The bean oils had lower pour points (−18 to −11 °C) compared to −9 °C for soybean oil. Among the four bean oils, kidney bean oil had the highest acid value (15.4 mg KOH/g) and kinematic viscosities over a wide range of temperatures.     

Microemulsion polymerization of 1,3-butadiene

One-phase microemulsion regions at 25 and 60 °C and the polymerization at 60 °C in o/w microemulsion formed by 1,3-butadiene, water, and a mixture of the surfactants, dodecyltrimethylammonium bromide, and didodecyldimethylamonium bromide (3/1 w/w), are reported. The polybutadienes obtained here have similar characteristics to those of their homologous obtained by emulsion polymerization, with the only difference that the average particle size of the former (25–30 nm) was smaller by an order of magnitude. The obtained polymer had high average molecular weights, but the gel content at high conversion is lower than the value for a conventional emulsion polymerization. The DSC measurements showed that the polymer has a single glass transition temperature at −72.5 ± 1.5 °C.