Preparation of Deoiled Soy Lecithin by Ultrafiltration

Deoiling of soy lecithin through ultrafiltration (UF) using an inorganic ceramic membrane was examined in a favorable solvent medium (hexane). Phospholipid (PL) reverse micelles with an average particle size of 9.8 nm were prepared in a 1:3 soy lecithin/hexane system (m/m) with 9% water added at a temperature of 25 °C. Consequently, an inorganic ceramic membrane with a pore size of 5 nm was selected. UF was employed in continuous diafiltration mode at transmembrane pressure (TMP) of 0.25 MPa, and a final deoiled lecithin product with a high acetone insoluble (AI) content of 96.32% was obtained at a yield of around 84%.     

Egg-yolk lipid fractionation and lecithin characterization

Egg-yolk lecithin has phospholipid (PL) classes and a FA composition that differ from soybean lecithin and may have unique functional properties. The purposes of this research were to develop an effective method for extracting a sufficient amount to lecithin from fresh egg yolks and to evaluate its functional properties. Ethanol was used to dehydrate and partially extract the PL, after which hexane was used to extract the total lipids. A phase separation of the combined extracts resulted in neutral and polar lipid fractions. An acetone precipitation of PL from the final polar lipid fraction was necessary to remove the residual neutral lipids, especially cholesterol. The purity of PL in the lecithin product was 95%. Surface tension reduction, emulsion stability, and oxidative stability studies were conducted to characterize the functional properties of egg-yolk lecithin. Egg-yolk lecithin and soy lecithin had similar surface activities, as evaluated by the surface tension reduction in an aqueous system and the critical micelle concentration. Soybean lecithin created a more stable emulsion than egg-yolk lecithin. However, egg-yolk lecithin was more oxidatively stable than soybean lecithin.     

Effects of expander process on the phospholipids in soybean oil

Crude oils were extracted from soybean flakes and collets by conventional and expander processes, respectively. The phospholipids were removed by degumming, and the lecithins were produced by using commercial procedures. The effects of the expander process on the degumming efficiencies were evaluated. The differences in the phosphatide compositions of the oils and the lecithins produced from expander and conventional processes were compared by high-performance liquid chromatography. The phosphorus content indicated that expander-processed oil contained more phosphorus (985 ppm) than the conventional oil (840 ppm). However, the phospholipids in the expander-processed oil were more hydratable than those in the conventional oil. After degumming, the phosphorus content in the expander-processed and conventional oil were reduced by 93.2 and 78.6%, respectively. The expander-processed lecithin contained 74.3% acetone-insoluble matter (AI), and the conventional lecithin contained 65.8%. More phosphatidylcholine was found in the expander-processed lecithin (39.78%, based on AI) than in the conventionally processed lecithin (34.19%). The phosphatidylinositol contents of the expander-processed lecithin and the conventional lecithin are almost the same (19.95 and 19.97%). The phosphatidylethanolamine in the expander-processed lecithin (12.36%) was lower than that in the conventional lecithin (18.07%).     

Evaluation of phosphoglycolipid elimination from rice bran oil by a nonporous membrane using NMR spectroscopy

The presence of phosphoglycolipids (PGL) in degummed rice bran oil (RBO) affects the color in the subsequent refining process, posing problems in producing a final product of acceptable quality. A nonporous membrane could achieve near complete removal of phospholipids even under hexane‐diluted conditions, including PGL present in RBO. PGL from glycolipid fractions isolated from various membrane process stream samples, analyzed by ¹H, ¹³C and ³¹P NMR spectroscopic techniques, indicated the absence of PGL in the permeate, besides identifying them to be oleates/linoleates of phosphatidic acid. Hence, the efficacy of a nonporous membrane in the removal of PGL suggests its application for effective degumming of crude RBO.     

Mapping the Chemical Variability of Vegetable Lecithins

There is an increasing interest in vegetable lecithins because of their broad usage in many food and cosmetic applications. In this research, the chemical variability of commercial lecithins from soy, sunflower and rapeseed were mapped. The acetone insoluble matter, total phospholipid content and their compositions were determined. Significant correlation coefficients were observed between phosphatidylcholine and phosphatidic acid (?0.84), phosphatidylethanolamine and phosphatidylinositol (?0.86), monounsaturated fatty acid and polyunsaturated fatty acid (?0.97). Principal component analysis was used to group the lecithins according to their sources. Rapeseed lecithin was found to be the most different product compared to soy and sunflower lecithin.     

Soy lecithin-monoester interchange reaction by microbial lipase

Modification of the fatty acid composition of soy lecithin, principally at its 1-position, was investigated by interchange reaction with the methyl ester of individual fatty acids and a lipase as the catalyst. The consequent effect on the surface activity of soy lecithin was also examined. The interchange reaction was carried out by heating a mixture of soy lecithin and methyl ester of a fatty acid at 60°C for 48 h with 10% (by weight of the reactants) Mucor miehei lipase. The lipase was filtered from the reaction mixture, and the product was isolated by combination of acetone extraction, which removed the methyl ester fraction, and by preparative thin-layer chromatography separation. The soy lecithin showed distinct change in its fatty acid composition in the sn-1 position. Capric acid was incorporated by 8.4%, while lauric acid and myristic acid were introduced at 14.1 and 15.7%, respectively. The linolenic acid percentage was increased by about 10 units. The interfacial tension of soy lecithin changed significantly after incorporation of various saturated fatty acids.     

Fractionation of crude soybean lecithin with aqueous ethanol

Aqueous ethanol was used to fractionate soybean PC and PI, which have dissimilar solubilities in this solvent. The effects of oil and moisture contents of the crude lecithin, ethanol-to-lecithin ratio, and dispersion temperature on the efficiency of phospholipid (PL) fractionation were investigated. Yield, purity, recovery, and PL class composition were examined. Yield was defined as the amount of fractionated material, divided by the acetone-insoluble (AI) matter in the starting material; purity was the percentage of PL (PC+PE+PI) as quantified by HPLC in the fraction; and recovery was the amount of PL quantified relative to the quantity of AI matter. Higher oil contents significantly increased the yield of the PC fraction, but they significantly decreased yield, purity, and recovery of the PI fraction. They also significantly affected the PL composition of the PC fraction. Higher moisture contents significantly decreased the yield but slightly increased the purity of PC fractions. Higher temperatures significantly increased the yield and recovery of the PC fraction. They also affected the relative proportion of PL classes in the PC and PI fractions. The ethanol-to-lecithin ratio significantly affected yield, purity, and recovery as well as the relative proportions of PL in both PC and PI fractions. A combination of multiple fractionation and high-low temperature treatment was also examined. Fractionating twice with ethanol increased the purity of the PC fraction. High-low temperature fractionation increased the purity and PC percentage in the PC fraction.     

Deacidification of model vegetable oils using polymeric membranes

Selectivity of polymeric hydrophobic nonporous and hydrophilic nanofiltration (NF) membranes was assessed for the deacidification of model vegetable oils with and without addition of organic solvents. In the model undiluted system, oleic acid permeated preferentially over triacylglycerols in the nonporous membrane, over a wide range of concentrations (?5–70%). The effect of oleic acid concentration on selectivity indicated that the solubility of triacylglycerols in oleic acid played a role in determining the selectivity, besides the solubility and diffusivity of the permeating components. Dilution with hexane improved oil flux by 14‐fold; however, membrane selectivity was completely lost as both triacylglycerols and oleic acid permeated along with the solvent, which clearly showed that the solvent played a greater role than the membrane. Processing of the model oil after diluting with acetone showed that oleic acid was retained less than triacylglycerols by the NF membrane, resulting in higher selectivity (7), indicating its potential. However, the selectivity decreased during successive runs, owing to the gradual loss of hydrophilicity due to polarity conditioning of the membrane. The differences in molecular size, solubility, diffusivity and polarity between triacylglycerols and oleic acid appear insufficient for achieving direct deacidification in terms of reasonable selectivity and throughput with these two membranes. Direct deacidification using membranes still remains as a challenge.     

Phospholipid class and FA compositions of modified soybeans processed with two extraction methods

Soybean lecithin is used as an emulsifier in food, cosmetic, and pharmaceutical industries. The proportion of individual phospholipids (PL) and their FA composition may affect the functional properties of lecithin. In this research, lecithins recovered from four modified soybeans and one commodity soybean, which were processed by extrusion-expelling and conventional solvent extraction, were analyzed for proportion of PL class and FA composition. HPLC with an ELSD analysis demonstrated that the percentage of PC in extrusion-expelled lecithin was higher than in solvent-extracted lecithin, whereas the PE content was lower. GC analysis showed that FA compositions of the PL varied with soybean type. The oil extraction method did not significantly affect FA composition. Critical micelle concentration tested with a tensiometer showed differences among the lecithins.     

高PC含量的大豆磷脂的制备研究

提出了制备高磷脂酰胆碱 (PC)含量的大豆磷脂的新工艺。用异丙醇作溶剂 ,通过正交实验得出优化的分离条件为 :抽提时间 5min ;抽提温度 - 5℃ ;m(磷脂 )∶m(异丙醇 ) =12∶15 7;异丙醇的体积分数 φ(异丙醇 )≈ 10 0 % ;HPLC分析结果表明 ,抽提后产品中PC的含量可以从原料中的w(PC) =2 5 6 %提高到w(PC) =6 6 8%。收率为 2 2 4%。     

Development of Industrially Scalable Method for Phospholipids and Branch-Chain Fatty Acids of Dairy by-Product

Dairy phospholipids (PL) is of interest due to their health benefits and functional properties. Solvent fractionation of PL has not been commonly used in the dairy industry to fractionate milk fat to obtain or concentrate the PL. The total lipid extracted from the β stream, a waste by-product of dairy processing, was used in this study to investigate suitable solvent and conditions to separate the neutral lipid from PL. A fixed lipid solvent ratio (1:10 g/v) was used at various fractionation temperatures (−20, 2, 15, 23, 40, and 60 °C) depending on the solvents. The use of acetone at 23 °C, not at the lower temperatures, led to a dairy lecithin product with high PL content, such as 71.5%. The more aqueous ethanol, i.e. at 70% concentration compared to 95%, was able to preferentially extract PL to form products with up to 74.7% PL, but the PL yield was much lower (26.3%) compared to acetone precipitation (97.9%). The enrichment of branch chain fatty acids proved to be very challenging due to the overlapping melting points with other fatty acids. The composition of the major fatty acids of polar and neutral lipids also showed interesting patterns that may indicate different nutritional and oxidative properties of the fractionated products.     

蛋黄磷脂的提纯

利用蛋白质不溶或微溶于某些溶剂的特点,用混合溶剂萃取粗蛋黄磷脂制备精蛋黄磷脂的工艺,该工艺易于实现工业化生产,磷脂纯度可达98%以上。     

Separation of oil constituents in organic solvents using polymeric membranes

Different types of commercial nonporous (reverse osmosis and gas separation) polymeric membranes were screened for their abilities to separate FFA, MG, DG, and TG from a lipase hydrolysate of high-oleic sunflower oil after diluting it with organic solvents (ethanol and hexane). Cellulose acetate (CA) (NIR-1698) membrane gave the largest difference in rejection between FFA and glycerides and high flux in oil/ethanol mixtures. In the hexane system, the values of permeate flux and rejection were generally lower than those in the ethanol system. The silicone-polyimide composite membrane (NTGS-2100) gave the highest flux and rejections of solutes (70.2% for FFA, 94.4% for TG) in oil/hexane mixtures. In the ethanol system with the CA membrane, TG had the highest rejection (98%) followed by DG (90%) and MG and FFA (50–70%) when the oil concentration was varied from 6.3 to 45.8%. A discontinuous diafiltration process (16 batches) using the CA membrane with ethanol changed the composition of the oil from 31∶28∶9∶32 TG/DG/MG/FFA to 65∶30∶1∶4. The results of this study showed that oil constituents can be separated in suitable solvents using appropriate nonporous membranes.     

Rapid equilibrium extraction of rice bran oil at ambient temperature

Rapid equilibrium extraction of soybean flour has been effective in obtaining an oil with reduced phospholipid content. This technique was examined to obtain a low phospholipid and low free fatty acid rice bran oil (RBO). The amount of RBO extracted with hexane from 1 g of rice bran at 22°C was measured over a 10-min period. The amount of oil extracted from variable amounts of bran with a fixed volume of solvent was also studied. Ninety percent of the oil was extracted in one minute, with 93% of the total RBO being extracted after ten minutes. This compares with the 98% yield obtained from soy flour, but increasing the amount of bran used did not reduce the extraction rate. This extraction method produced a good quality RBO with low phospholipid, low free fatty acid and low peroxide values.     

Degumming,Dewaxing and Deacidification of Rice Bran Oil-Hexane Miscella Using Ceramic Membrane: Pilot Plant Study

An indigenously developed low-cost clay-alumina-based ceramic microfiltration membrane of 19-channel configuration has been evaluated for degumming, dewaxing and deacidification of rice bran oil (RBO) miscella having different oil contents at pilot scale. Rice bran wax and soap particles in miscella will aggregate with changes in temperature. This suggests a technique for their effective separation. Low-temperature cross-flow membrane filtration was used for single-stage degumming-dewaxing and showed 70 % and 80 % removal of acetone insoluble residue from two RBO miscella samples, respectively. Color reduction was 50 %, and oryzanol retention was 70 %. NaOH was used for deacidification in a 10 % excess of that required based on the free fatty acid content in oil. This reduced free fatty acids to 0.2 %. Operating for 10 h with a 0.7 bar trans-membrane pressure, permeate fluxes of 15 and 8 L/m² hr were obtained for the degumming-dewaxing and deacidification operations, respectively. The process has advantages, such as high micronutrient content (1.56 % oryzanol) and negligible oil loss (2.6 %). Moreover, ceramic membrane processing of RBO miscella could be an effective pre-treatment step with respect to micronutrient enrichment, elimination of heating, neutral oil recovery and a viable option for solvent separation.     

Enzymatic hydrolysis of oat and soya lecithin: Effects on functional properties

Enzymatic hydrolysis of oat and soy lecithins and its effects on the functional properties of lecithins were investigated. The phospholipase used was most efficient at low enzyme and substrate concentrations. More fatty acids were released from soy lecithin than from oat lecithin. The maximum degree of hydrolysis was 760 μmol free fatty acids per gram soy lecithin and 170 μmol free fatty acids per gram oat lecithin. On the basis of the total carbohydrate and phosphorus contents in the polar fractions of the lecithins, oat lecithin contained more glycolipids and less phospholipids than soy lecithin. With regard to functional properties, the stability of oil-in-water emulsions was enhanced by hydrolyzed soy lecithin and by crude and hydrolyzed oat lecithins, but only hydrolyzed soy lecithin prevented the recrystallization of barley starch. The dissociation enthalpy of amylose-lipid-complex (AML-complex) was significantly higher when hydrolyzed soy lecithin was present. Hydrolyzed oat lecithin slightly affected the dissociation enthalpy of AML-complex. The other lecithins had no effect on recrystallization or dissociation enthalpies in the barley-starch matrix.     

Effects of the extraction conditions on the yield and composition of rice bran oil extracted with ethanol—A response surface approach

Rice bran oil was obtained from rice bran by solvent extraction using ethanol. The influence of process variables, solvent hydration (0-24% of water, on mass basis), temperature (60-90 °C), solvent-to-rice bran mass ratio (2.5:1 to 4.5:1) and stirrer speed (100-250 rpm) were analysed using the response surface methodology.The extraction yield was highly affected by the solvent water content, and it varied from 8.56 to 20.05 g of oil/100 g of fresh rice bran (or 42.7-99.9% of the total oil available) depending on the experimental conditions. It was observed that oryzanol and tocols behave in different ways during the extraction process. A larger amount of tocols is extracted from the solid matrix in relation to γ-oryzanol. It was possible to obtain values from 123 to 271 mg of tocols/kg of fresh rice bran and 1527 to 4164 mg of oryzanol/kg of fresh rice bran, indicating that it is feasible to obtain enriched oil when this renewable solvent is used. No differences in the chemical composition of the extracted oils were observed when compared to the data cited in the literature.     

Turbidimetric measurement of haze in canola oil by acetone precipitation

Formation of turbidity in canola oil was facilitated with addition of acetone, and a method to measure the sediment content based on the oil turbidity has been developed. Canola oil was mixed with acetone at the ratio of 60:40, and the turbid solution developed in an ice bath for 20 min. The turbidity of the oil solution was determined by a turbidimeter. The relation between turbidity of the oil solution and sediment content was nonlinear and could be correlated by a second-order polynomial. There was no difficulty in the development of turbidity in canola oil solutions in the presence of added lecithin (2%, w/w). However, with added lecithin, turbidity was 23% higher at the same sediment content.     

Processing of tocopherol and FA systems using a nonporous denser polymeric membrane

Tocopherols permeated preferentially over oleic acid in model systems and over oleic acid and other oil constituents during processing of soy deodorizer distillate (DOD) when using nonporous denser polymeric membranes (i.e., denser than reverse osmosis membranes). This observation was unexpected, since the separation in a denser membrane is generally based on a solution-diffusion mechanism. That tocopherols are less polar than oleic acid appears to have facilitated the preferential permeation of tocopherols through the hydrophobic membrane. Selectivity of the membrane for tocopherols improved with esterified soy DOD. The presence of FAME decreased the viscosity of the feed and thereby increased convective flow, which in turn improved permeate flux. FAME appeared to have exerted positive coupling effects with tocopherols, having better selectivity in spite of the greater solubility of FAME in the membrane material. Membrane selectivity for tocopherols improved upon dilution of the feed material with hexane, perhaps owing to greater solubility of tocopherols in hexane (nonpolar) than other feed constituents.     

Extraction of egg-yolk lecithin

In this research, the extraction of egg-yolk lecithin with ethanol was studied. Extraction was performed with deoiled and undeoiled yolks and with heated and unheated yolks. The yield of the extracted fraction relative to the initial material, phospholipid (PL) purity, and cholesterol content of both the PC-enriched fractions and the remaining PL fractions were determined. The yield and PL purity of the PC-enriched fractions obtained from the undeoiled yolks were 23.9 and 35.7%, and those obtained from deoiled yolks were 13.5 and 53.3%. The recovery of total PL in the two fractions was higher from the undeoiled (70%) than from the deoiled yolks (60%). However, heating had a negligible effect on PL extraction. Better enrichment of PC was observed by extraction from the undeoiled than from the deoiled yolks. The cholesterol content of the PC-enriched fraction obtained from the undeoiled yolks was much higher than that from the deoiled yolks.