A Simple Enzymatic Approach for Selective Acetylation of Phosphatidylethanolamine

Acetylation of lecithin improves the fluid properties, water dispersibility and emulsifying properties of a variety of food formulations. Acetylation of lecithin is usually carried out chemically using acetic anhydride in the presence of tertiary amine. In the present study acetylation of soybean lecithin and egg yolk lecithin was carried out using lipozyme IM 20 having 1,3-specificity from Mucor miehei and vinyl acetate at 70–75 °C. Vinyl acetate played a dual role as acetylating agent and also as the solvent medium. This method selectively acetylated phosphatidylethanolamine without effecting phosphatidylinositol since the enzyme employed was 1,3-specific.     

Studies on stability of rapeseed wet gum as a source of pharmaceutical lecithin

Lecithin wet gum with high water content is less stable during storage than dry lecithin. Deoiling and dehydrating the fresh gum can result in a purified lecithin of high quality. The stability of rapeseed wet gum obtained from double-zero rapeseed varieties was determined at various temperatures. The effect of storage time on volatile substances, acetone insolubles, neutral lipids and acid, iodine, and peroxide values were investigated. The rapeseed wet gum stored a little above 20°C is stable for up to ten days, although in the frozen state (−20°C) no changes in general composition, acid, iodine, and peroxide values were observed during 24 mon of storage.     

Effect of Phospholipids on Crude Linseed Oil Filtration

Abstract

Lecithin addition (0 to 10%) in crude linseed oil was used to investigate the effect of phospholipids on oil filtration at 20°C. The addition of lecithin (more than 2%) results in a decrease in the filtration rate, an increase in the cake resistance, and a modification of the filtration mechanism from cake resistance to intermediate blocking. At 20°C the lecithin precipitated on the particles and caused sedimentation of a deposit impermeable to oil that slows down the oil flow through the cake. The magnetic stirring is not an efficient way of filtration improvement on the contrary of filtration at 50°C.     

The thermal decomposition of granular and fluid soybean lecithins

The effect of heat on the decomposition of two grades of soybean lecithin has been examined up to 600°C using differential scanning calorimetry and thermogravimetry. Studies were carried out in both air and argon and a kinetic analysis of the isothermal rates of reaction was attempted. Three principal decomposition stages were distinguished in argon and four in air for a water-dispersible lecithin typical of the quality of the material used in many industrial applications. Gas chromatography showed that the principal gases evolved from 50 to 600°C in argon from the water-dispersible lecithin in contact with aluminum surfaces were C₁-C₆ hydrocarbons, carbon dioxide, carbon monoxide, water and traces of hydrogen.     

The Preparation of Rapeseed Lecithin with High Phosphatidylcholine Content

The raw commercial rapeseed lecithin free of erucic acid and glucosinolate (00-type) was purified by deoiling with acetone and extracting with ethanol. The increasing of phosphatidylcholine (PC) content (from 50 to 70–80%) in obtained rapeseed lecithin extract was performed. It was done by column chromatographic fractionation using a low silica gel–lecithin extract ratio about 2:1 and the various temperatures up to 60°C. The fractions were eluted with 95% ethanol. Effect of rapeseed lecithin column fractionation temperatures is significant and the better purification quality in the higher temperatures was observed. Based on performed investigations it could be summarized that the low silica gel–lecithin extract ratio (2:1) allows to obtain rapeseed lecithin with above 80% content of PC and the best results for temperature 60°C were observed.     

A kinetic study of vinyl acetate polymerization in aqueous media in the absence of emulsifier

In the absence of emulsifying agents, vinyl acetate polymerization in aqueous media was carried out at 50°C over a wide range of initial initiator and monomer concentrations to clarify the effect of reaction conditions on the kinetic behavior of the polymerization system. It was shown that the rate of polymerization was proportional to reaction time and initiator concentration and independent of the number of polymer particles present. The rate could also be successfully explained by the Smith and Ewart theory for emulsion polymerization when the dissolved monomer in water and the Trommsdorff effect were taken into consideration. A set of equations which could account for the effect of dissolved monomer in water on the rate of polymerization is proposed.     

Sources of color in soybean “lecithin”

The color of soybean lecithin is due to carotenoids, brown pigments, and occasionally porphyrins. In the water-washing of crude oil xanthophylls are preferentially removed with the gums, and carotene is practically absent in lecithin. Lutein is the principal carotenoid, comprising about three-quarters of the carotenoids in lecithin. Hydrogen peroxide bleaching destroys all the color to some extent, but by far the greater effect is on the carotenoids. The brown color is very likely an aldehyde amine reaction product. It is largely formed by heating of the oil during the solvent-stripping operation. It is not increased by drying the gums under vacuum for 3 hours at 80°C. but it is increased on heating at 100° C. under the same conditions. The formation of the brown color is not prevented by removal of free sugars or by hydrogenation of the lecithin.     

Evaluation of antioxidants for cod liver oil by chemiluminescence and the rancimat method

Commercial blends of natural antioxidants,viz., tocopherol concentrates, rosemary extracts, sage extracts, and lecithins, were tested for their ability to stabilize cod liver oil. The antioxidants were tested by using the Rancimat apparatus at 80°C and by a method based on hypochlorite-activated chemiluminescence analysis of samples stored at 35°C for 24 h in light. In addition, a stability study at 5°C in the dark for 8 wk, under conditions realistic for normal consumption of cod liver oil was carried out. A low correlation (r=0.339) was found between Rancimat induction times and chemiluminescence data for the sixteen antioxidant systems tested, probably due to temperature differences, and different ways of detecting oxidation products. Based on Rancimat induction times, δ-tocopherol-rich antioxidants and lecithin had the best stabilizing effect. However, based on the chemiluminescence method, the tocopherols acted as prooxidants, while tocopherols with lecithin increased the stability. Both Racimat and chemiluminescence data showed stabilizing effects with rosemary and sage extracts, but no synergistic effect between the herbal extracts and lecithin or tocopherol was observed. Analyses of oil aged at 5°C for 8 wk showed the highest stability for cod liver oil containing rose-mary extracts. The tocopherol mixtures showed only a minor effect on the stability. Ranking of antioxidants varied considerably depending on the method used, and increasing the temperature seemed to decrease the usefulness of the method. Antioxidant evaluation has to be done by using as many evaluation methods as possible under conditions relevant for normal storage and use.     

Thermomechanical properties and water uptake capacity of soy protein‐based bioplastics processed by injection molding

The optimization of the processing conditions in the production of soy protein bioplastics by injection molding has been essential in order to develop materials with a great capacity to absorb water while displaying good mechanical properties. Using a 50/50 (wt/wt) soy protein/glycerol mixture, and 40 °C, 500 bar, and 70 °C as reference values for cylinder temperature, injection pressure, and mold temperature, respectively, the effect of those processing parameters over thermomechanical and hydrophilic properties was studied. Processing parameters did not show a great influence over the thermomechanical bending properties within temperatures ranging from ?30 to 130 °C, as most samples displayed a similar response, independently of the parameter studied. On the other hand, when studying tensile and hydrophilic properties, the main effect corresponded to the cylinder and mold temperature values, as pressure did not exert a clear influence when increased from 300 to 900 bar. Samples with a lower water uptake were obtained when processed at higher temperature, as a result of crosslinking promotion. Moreover, a greater extensibility was observed when bioplastics are processed at high mold temperatures. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43524.     

Stability of Oil-in-Water Emulsions with Sunflower (Helianthus annuus L.) and Chia (Salvia hispanica L.) By-Products

Emulsifiers and stabilizers play an important role in emulsion stability. Optical characterization and droplet size distribution of oil‐in‐water emulsions formulated with different types and concentrations of modified sunflower lecithin [phosphatidylcholine (PC) enriched lecithin and deoiled sunflower lecithin], with or without chia mucilage (0.75 % wt/wt), have been evaluated as a function of storage time at 4 ± 1 °C. Emulsions with PC‐enriched lecithin (without chia mucilage) exhibited the highest stability at the different concentrations because of the high PC/phosphatidylethanolamine ratio in comparison to Control lecithin. The addition of 0.75 % wt/wt mucilage contributed to obtain stable emulsions for all type and concentrations of emulsifiers studied, mainly with PC‐enriched lecithin due to the reduction of the mobility of oil particles by the formation of a tridimensional network.     

Dairy Lecithin from Cheese Whey Fat Globule Membrane: Its Extraction, Composition, Oxidative Stability, and Emulsifying Properties

An ethanol extraction method was studied for the production of dairy lecithin from cheese whey-derived milk fat globule membrane (MFGM). A two-step ethanol extraction of MFGM involving first extraction at pH 6.5, followed by second extraction at pH 4.5 yielded 17.2 % lipids. The extracted material contained about 90 % lipids, 4.5 % ash, and 1.2 % moisture. The phospholipid content of the ethanol extract was 31 % and the remainder was mostly neutral lipids. The phospholipid fraction contained 34 % sphingomyelin, 31 % phosphatidylcholine, 27 % phosphatidylethanolamine, 4.6 % phosphatidylserine, and 3.1 % phosphatidylinositol. Since the ethanol extract contained 31 % phospholipids, it can be technically termed as dairy lecithin. The major fatty acid components were linoleic acid (5.1 %), myristic acid (8.3 %), palmitic acid (29 %), stearic acid (14 %), oleic acid (25 %), and the remainder was minor fatty acids with chain length ranging from C4:0 to C22:5. The dairy lecithin was semi-solid at room temperature and exhibited a major phase transition at about 35 °C. Owing to its low polyunsaturated fatty acid content, the dairy lecithin was reasonably stable to oxidation as measured by the rate and extent of hexanal production during 35 days of storage at 45 °C. Oil-in-water emulsions made with less than 2 % dairy lecithin (relative to the total emulsion weight) were unstable; however, emulsions made with greater than 4 % dairy lecithin were very stable for more than 60 days at room temperature. The results of this study indicated that a highly functional dairy lecithin can be commercially produced using cheese whey-derived MFGM as the starting material.     

Emulsifying Properties of Lecithin Containing Different Fatty Acids Obtained by Immobilized Lecitase Ultra-Catalyzed Reaction

Lecitase Ultra and 6 triacylglycerol lipases (lipases PS, M, AH, AY, R, and AK) were immobilized on Amberlite XAD 7HP and used to catalyze the acidolysis reaction between lecithin and capric acid (C10:0) for comparison. The highest molar incorporation value (51.0 mol%) was observed for the immobilized Lecitase Ultra. Further, immobilized Lecitase Ultra was selected for catalyzing acidolysis between lecithin and fatty acids with different chain lengths (C6:0, C8:0, C10:0, C12:0, and C14:0). After reaction, free fatty acids were removed by SPE and the resultant was called modified lecithin fraction 1 (MLF1). The highest molar incorporation value was obtained for C10:0 (51.0 mol%) at 45 °C with a mole ratio of 10/1 (C10:0/lecithin) for 72 h. After removal of lysophosphatidylcholine by solid-phase extraction from MLF1, the resultant modified lecithin fraction 2 (MLF2) was used to prepare an oil-in-water emulsion. All emulsions prepared with MLF2 exhibited significantly higher emulsion stability (ES) values (16.2–17.7) and smaller particle sizes (d ₃₂ 0.40–0.49 μm, d ₄₃ 0.75–1.01 μm) than the emulsion prepared with unmodified lecithin (ES 14.1, d ₃₂ 0.76 μm, d ₄₃, 1.26 μm) (P < 0.05). Furthermore, less clarification and droplet aggregation were observed in emulsions prepared with MLF2 than in lecithin-based emulsions. Overall, the MLF2s showed better emulsifying properties than lecithin.     

Micronization and characterization of squid lecithin/polyethylene glycol composite using particles from gas saturated solutions (PGSS) process

Lecithin was isolated from squid viscera residues after supercritical carbon dioxide (SC-CO₂) extraction at 25 MPa and 45 °C. The particle formation of squid lecithin with biodegradable polymer, polyethylene glycol (PEG) was performed by PGSS using SC-CO₂ in a thermostatted stirred vessel. By applying different temperatures (40 and 50 °C) and pressures (20–30 MPa), conditions were optimized. Two nozzles of different diameters (250 and 300 μm) were used for PGSS and the reaction time was 1 h. The average diameter of the particles obtained by PGSS at different conditions was about 0.74–1.62 μm. The lowest average size of lecithin particle with PEG was found by the highest SC-CO₂ density conditions with the stirring speed of 400 rpm and nozzle size of 250 μm. The inclusion of lecithin in PEG was quantified by HPLC. Acid value and peroxide value was measured after micronization of lecithin.     

Application of the Conant-Finkelstein Reaction to the Modification of PVC: Iodinated PVC

The Conant-Finkelstein reaction was applied to PVC with the aiming of replacing the chlorine atoms with iodine ones. The effect of reaction temperature with regard to the characteristics of the modified PVC was significant. Formation of a gel and degraded polymeric materials was observed when working at temperatures higher than 60 °C. The degraded polymer formed at 70 °C was insoluble and gave rise to a polyacetylene-like chain with a melting point of 60 °C. However, the reaction on PVC at lower temperatures resulted in soluble polymers which were easily amenable to spectral characterization. The molecular weights of the iodine-modified PVCs were temperature-dependent. At 40, 45, 50 and 60 °C, molecular weights lower than that of the initial PVC were measured; however, at 35, 30 and 25 °C, a gain of about 9% in molecular weight was seen. Substitution and elimination reactions occurred to different extents depending mostly on temperature. Optimal substitution was obtained at 50 °C for a reaction time of 20 h.     

Rhamnolipids Obtained from a PHA-Negative Mutant of Pseudomonas aeruginosa 47T2 ΔAD: Composition and Emulsifying Behavior

Pseudomonas aeruginosa 47T2 (NCBIM 40044) synthesizes polyhydroxyalkanoic acids (PHAs) and rhamnolipids (Rhls). The knockout mutant for PHAs biosynthesis, P. aeruginosa 47T2 ΔAD prepared in this study, increased the cellular yield of Rhls production by 28 %. The Rhls mixture (composed up to eight homologs) reduced the water surface tension to 31.67 mN/m with a critical micelle concentration of 105 mg/L. The IC₅₀ (μg/mL) of the neutral red uptake assay and methylthiazol tetrazolium assay ranged between 53.9 and 72 μg/mL, which is similar to that of sodium dodecyl sulfate (SDS). Rhamnolipids had a lower hemolytic effect at 110.8 μg/ml than SDS, a commercial anionic surfactant, at 43.6 μg/mL. This suggests that the Rhls mixture could be used in topical pharmaceutical and cosmetic applications or cleansers as a biosurfactant. The emulsifying properties in water/oil dispersions were determined using ternary phase diagrams at 25 °C. Isopropyl myristate, soybean oil, olive oil and Casablanca oil were used as the oil components. Total emulsions were obtained with most of the oils.     

The use of reverse osmosis for the treatment of river Rhine water. Part II

The article describes an investigation into membrane fouling and flux decline in the reverse osmosis treatment of river Rhine water. Special attention is paid to technical applications and process optimization. The investigations involve the effect of a number of relevant process variables, such as the extent of the pretreatment of the raw Rhine water (rapid sand filtration, chemical clarification with various degrees of floc removal and tapwater treatment), membrane quality (tubular, cellulose acetate, cured at 75°C, 80°C and 86°C), brine velocity (75 up to 150 cm/sec), pressure (20, 30 and 40 atm.) and recovery (50%, 75% and 90%).The results show a great effect of each of the process variables on membrane fouling and flux decline. It seems preferable to pretreat the raw Rhine water by chemical clarification and sand filtration and to operate high capacity installations at 20 atm., 90% recovery and brine velocities of about 75 cm/sec. Operating at 20 atm. instead of 40 atm. seems profitable as it saves energy and installation costs, and because it presents less fouling problems and is consequently an easier operation.     

Evaluation of Soy Lecithin as Eco‐Friendly Biosurfactant Clathrate Hydrate Antiagglomerant Additive

Hydrate plug formation is one of the most challenging problems in upstream oilfields. The most preferred option to prevent hydrate plug formation is the use of antiagglomerants in the oil/gas flowlines and in drilling fluids. Antiagglomerants do not prevent hydrate formation but restrict the hydrate crystals from agglomerating. In this study, experiments were conducted on of soy lecithin (biosurfactant) at different concentrations to measure its effectiveness as an antiagglomerant additive. In all the experiments, tetrahydrofuran (THF) hydrate was used, and to study the antiagglomerant efficiency of the additive, visual observation was utilized. Soy lecithin was compared with cetyltrimethylammonium bromide (CTAB), and the former was found as a good environmentally friendly antiagglomerant additive. Soy lecithin at 0.1 wt% in the experimental solution increased the agglomeration time of hydrate crystals by more than 1440 min and showed agglomeration state III at 1 °C. Soy lecithin at 0.01 wt% increased the agglomeration time of hydrate crystals to 1000 min. The effect of soy lecithin on the rheological characteristics and filtration properties of drilling fluid was also studied. Even at the highest concentration of 1.0 wt% soy lecithin and at a temperature of 1 °C, the rheological parameters of the drilling fluid remained within permissible limits. Soy lecithin was thus found to effectively restrict the agglomeration of hydrate crystals.     

Antioxidant activity of green teas in different lipid systems

Different commercial green teas from Japan, China, and India, were compared in different lipid systems. Green teas were active antioxidants in bulk corn oil oxidized at 50°C but were prooxidant in the corresponding oil-in-water emulsions. Green teas also were active antioxidants in soybean lecithin liposomes oxidized at 37°C in the presence of cupric acetate as catalyst. At 50°C, however, three of the samples of green tea were active antioxidants in the absence of copper catalyst, and two samples showed prooxidant activity in the presence of copper catalyst. The marked variation in activity among green tea samples may be due partly to differences in their relative partition between phases in different lipid systems. The improved antioxidant activity observed for green teas in lecithin liposomes compared to corn oil emulsions can be explained by the greater affinity of the polar tea catechin gallates for the polar surface of the lecithin bilayers, thus affording better protection against oxidation. Liposomes may thus be appropriate lipid models to evaluate antioxidants for foods containing phospholipids.     

Controllable fabrication of superhydrophobic alloys surface on 304 stainless steel substrate for anti-icing performance

In this paper, 304 stainless steel-based ZnO (304SS-based ZnO) seed layer was prepared by using sol-gel method or electrochemical deposition. Superhydrophobic nano-ZnO (CSS–ZnO) surface were prepared on its surface by hydrothermal method. The results show that different structural morphologies of 304SS-based ZnO surface were prepared by varying different seed layer preparation methods. In the static icing test, compared with hydrophilic nano-ZnO (SS–ZnO) surface, hydrophobic nano-ZnO (QS-ZnO) surface and 304SS surface at −5 °C, −10 °C and −15 °C. The icing time of CSS-ZnO surface was prolonged by about 2.7 h at −5 °C, delayed by about 40 min at −10 °C and delayed by about 9 min at −15 °C. The CSS-ZnO surface is the most effective surface in static anti-icing. It is because that there has a residual air layer at the solid-liquid interface and the coating can still effectively retard ice formation in a partially wetted state. In the dynamic icing test, compared with QS-ZnO surface, SS-ZnO surface and 304SS surface at −16 °C, SS-ZnO surface and QS-ZnO surface have no anti-icing effect, and CSS-ZnO surface has a significant anti-icing effect. The mechanism for inhibiting condensation of water droplets by superhydrophobic surfaces was illustrated, which can be identified that the contact angle of the ice embryo will increase with the increase of the water contact angle. This work provides a practical application for promoting anti-icing ability of 304SS surfaces in industry.     

Lecithin‐enhanced biotransformation of cholesterol to androsta‐1,4‐diene‐3,17‐dione and androsta‐4‐ene‐3,17‐dione

A biotransformation process using Mycobacterium sp was studied for androsta‐1, 4‐diene‐3,17‐dione (ADD) and androsta‐4‐ene‐3,17‐dione (AD) production from cholesterol. Cholesterol has a poor solubility in water (～1.8 mg dm^?3 at 25 °C), which makes it difficult to use as the substrate for biotransformation. Lecithin is a mixture of phospholipids of phosphatidylcholine (PC) and phosphatidylethanolamine (PE), which behave like surfactants and can form planar bi‐layer structures in an aqueous medium. Therefore, a small amount of lecithin (<1 g dm^?3) can be used to form stable colloids with cholesterol at a relatively high concentration (20 g dm^?3) in water. In this work, an energy density of 1000 J cm^?3 from sonication was provided to overcome the self‐association of cholesterol and to generate a stable lecithin–cholesterol suspension that could be used for enhanced biotransformation. The lecithin–cholesterol suspension was stable and could withstand typical autoclaving conditions (121 °C, 15 psig, 20 min). In contrast to conventional surfactants, such as Tween 80, that are commonly used to help solubilize cholesterol, lecithin did not change the surface tension of the aqueous solution nor cause any significant foaming problem. Lecithin was also biocompatible and showed no adverse effect on cell growth. Compared with the medium with Tween 80 as the cholesterol‐solubilizing agent, lecithin greatly improved the biotransformation process in regard to its final product yield (～59% w/w), productivity (0.127–0.346 g dm^?3 day^?1), ADD/AD ratio (6.7–8), as well as the long‐term process stability. Cells can be reused in repeated batch fermentations for up to seven consecutive batches, but then lose their bioactivity due to aging problems, possibly caused by product inhibition and nutrient depletion. © 2002 Society of Chemical Industry