Lecithin production and utilization

Commercial lecithin is the most important byproduct of the edible oil processing industry because of its functionality and wide application in food systems and industrial utility. The recovery of lecithin from oil is a relatively simple process. Hydration of the phosphatides by water or steam followed by recovery by centrifuge and drying is all that is required. But in order to maximize lecithin’s utility and functionality, processing conditions all the way back to the bean or seed must be carefully controlled. Bean storage and handling, crude oil storage, refining pretreats, drying processes, bleaching, chemical modification, and storage all can affect lecithin quality and performance. The effects of processing on lecithin quality and performance is one of the major focal points in this presentation. Utilization of lecithins has expanded beyond the traditional application in paints, chocolate, and margarine. Food technologists have used lecithin as a functional ingredient in many modern systems. Its multifunctional properties and its “natural” status make commercial lecithin an ideal food ingredient. The major functional properties include: emulsification, instantizing and particle wetting, release, viscosity modification and nutrition. The nutritional impact of lecithin is currently being assessed in the medical field as an important factor in improving neurochemical disorders. Other medical and health related activity areas include positive changes in cholesterol, blood chemistry and circulatory factors. Lecithin is also used in numerous industrial and nonfood applications such as pigment dispersing, mold release, and animal feeds. The major source of commercial lecithin is from the processing of soybean oil. Evaluation of lecithins from other seed crops such as cotton, corn, and rapeseed is being pursued. The growth of these sources will be a function of demand.     

Sunflower Lecithin

Because of the increased domestic production of sunflower seed oil, by-products of oil processing such as meal and lecithin will be in greater supply. Lecithin content varies according to the type of sunflower seed produced. Removal of this material is greatly affected by seed condition and processing conditions. Conditions which favor optimal removal of phospholipids are also those for optimal oil quality. This review will cover some of the properties and processing details of lecithin production.     

卵磷脂的制备及改性

卵磷脂是一种天然表面活性剂,在许多方面有重要的应用价值。本文详细介绍了大豆卵磷脂的粗提、提纯、测定和改性方面的研究成果。     

天然磷脂在食品及药品加工等方面的应用

概述了天然磷脂在食品和药品等方面的应用。     

Lecithin in oil-in-water emulsions

Summary A study was made to investigate the use of purified phosphatide in I.V. emulsions. Lecithin isolated from egg yolk and purified by alumina and silica chromatography was analyzed by chromatographic strip techniques as a one-component material. Highly purified lecithin was found to be an inefficient emulsifier. Moreover emulsions containing highly purified lecithin were heat-sensitive. An emulsion physical stability test was developed to evaluate emulsifier formulations containing purified phosphatides for use with small amounts of emulsions (approximately 50 g.). Using this procedure, a considerable number of substances were tested as additives to enhance the purified lecithin's emulsifying power. None were found to be as effective as natural soybean phosphatide, which was used as a control. From these observations it is indicated that pure phosphatides are inefficient emulsifiers and that those phosphatide preparations possessing good emulsifying characteristics are presumably mixtures or complexes of the phosphatides with other substances. This investigation was supported in part by funds from the Office of the Surgeon General. One of the laboratories of the Southern Utilization Research and Development Division. Agricultural Research Service, United States Department of Agriculture.     

Lecithin gum rheology and processing implications

The rheology of canola, sunflower, and soybean lecithin gum was examined by studying samples of different moisture contents produced in a batch evaporator (70°C, 0.1 atm). Soybean lecithin was found to have the lowest viscosity, approximately 10 poise (100 s⁻¹, 70°C), compared to canola and sunflower lecithin with viscosities of approximately 90 and 90,000 poise, respectively. The high sunflower viscosity was attributed to the presence of long-chain waxes. Lecithin gum was shown to change from a Bingham (water continuous phase) to a pseudoplastic (oil continuous phase) type fluid as the moisture content of the lecithin gum decreased. The viscosity maxima occurred between 6.9 and 19.3% moisture content (100 s⁻¹), with the variation found to be related to the oil/water ratio of the system. Rheological results indicated that vertical scraped surface evaporator design could be optimized through the addition fluidizing of agents prior to the evaporator and/or increased heating at the evaporator outlet.     

蛋黄卵磷脂的提取及测定

从蛋黄中提取卵磷脂有两种思路，即直接用乙醇提取再用丙酮沉淀和直接用丙酮处理再用乙醇抽提，本文在参考文献的基础上，经实验比较，得到较合理的路线，收率为80%-90％。     

大豆磷脂的提取与分析

以新鲜的油脚为原料，经丙酮脱油，正已烷萃取，并以维生素Ｃ为抗氧化剂，制得粉状大豆磷脂。产品的各项指标不仅符合食品添加剂的标准，而且其色泽也有所改善．     

Die antioxidativen Eigenschaften von Lecithin

Antioxidizing Properties of Lecithin In various storage trials with sunflower oil and lard the antioxidizing properties of crude soybean lecithin as well as of its alcohol soluble and alcohol insoluble fraction could be proved. The addition of a very small quantity of these phospholipids to the oil after the refining process (prior to this process crude oil contains approx. 2–3% lecithin) improves the stability of these oils. The antioxidizing properties of phospholipids depend on: 1. composition of phospholipids, 2. tocopherol content of the oil. In our trials the alcohol soluble fraction of soybean lecithin performed the best antioxidizing results in sunflower oil by adding not less than 1%. In lard the same effect could already be reached with 0.1% of this fraction. As shown before, lecithin with a special phospholipid composition has antioxidizing properties and its addition in small quantities is beneficial to increase the stability of oils and fats. In new Japanese literature soybean saponines are the most favoured antioxidizing agents. Our trials did not confirm the results of these publications.     

大豆卵磷脂的研究现状

大豆卵磷脂是大豆油生产过程的副产品,是一种理想的多用途天然原料,具有十分独特的功能和作用,并已在许多领域内得到广泛的应用.本文介绍了大豆卵磷脂的化学结构、理化性质、应用、制备和分析等方面的研究概况,展示了其在食品、药品、化妆品等领域的应用前景.     

大豆卵磷脂的研究进展

大豆卵磷脂是大豆油生产过程的副产品,是一种理想的多用途天然原料,具有十分独特的功能和作用,并已在许多领域内与明胶相匹配得到广泛的应用。本文介绍了大豆卵磷脂的理化特性、制备方法,简述了大豆卵磷脂在食品、医药保健食品、化妆品等工业方面的开发与应用。     

The production and properties of filamentous carbon

Carbon filaments have been produced by the cobalt catalysed decomposition of 60 torr acetylene at 725°C. An upper pressure limit of 200 torr is set by polymerisation of acetylene. Pre-heating the acetylene increases filament yield, particularly at either 550 or 650°C. Addition of hydrogen to the acetylene produced a similar but somewhat smaller effect when it was pre-heated to these temperatures. The surface areas of many batches of filaments have been measured by adsorption of radioactive xenon at ?196°C. The values range from 9 to 153 m² · g^?1 depending on the preparation conditions and whether the measurement is made on filaments still bonded to the steel mesh support or on base filaments (when there is access to the inner cores of the filaments). The densities, 2°48 g · cm^?3, indicate that a significant amount of catalyst metal is retained in the filaments. Controlled atmosphere electron microscopy has been used to follow the absorption of water vapour by filaments at ambient temperature.     

蛋黄卵磷脂中鞘磷脂的分离与结构鉴定

目的:通过柱层析与高效液相色谱方法对蛋黄卵磷脂中的鞘磷脂进行制备分离,采用ESI质谱、GC-MS、核磁共振方法对鞘磷脂进行结构鉴定。结论:从蛋黄卵磷脂中分离鉴定了5种鞘磷脂,分别是N-棕榈酰-3-磷酸胆碱酰鞘氨醇、N-亚油酰-3-磷酸胆碱酰鞘氨醇、N-油酰-3-磷酸胆碱酰鞘氨醇、N-硬脂酰-3-磷酸胆碱酰鞘氨醇以及N-花生四烯酰-3-磷酸胆碱酰鞘氨醇。蛋黄卵磷脂中鞘磷脂成分的全面分析为蛋黄卵磷脂的产品质量研究以及鞘磷脂在医药方面的药理研究与应用等方面提供物质结构参考。     

Laboratory Studies on Membrane Deoiling of Lecithin

Deoiling of lecithin using a nonporous membrane was examined in a favorable solvent (hexane) medium with soy and rice bran lecithins. During the membrane process, the acetone insoluble (AI) content of soy lecithin increased from 63.2 to 81.0% in a single step batch operation. The membrane exhibited an excellent selectivity since phospholipid (PL) reverse micelles formed in the system were rejected almost completely due to low solubility probably aided synergistically by size exclusion. Diafiltration achieved greater oil removal from lecithin as reflected in terms of higher AI and PL contents in the deoiled lecithin. In discontinuous diafiltration, the PL content increased from 33.3 to 85.5% in rice bran lecithin (150% dilution to feed) and 56.6 to 85.7% in soy lecithin (200% dilution), respectively. The simulated continuous diafiltration run showed slightly greater PL content in soy lecithin (91.3%) compared to discontinuous diafiltration (89.7%) besides offering higher productivity. The membrane showed a color reduction of ~60% in soy lecithin but there was no improvement in rice bran lecithin due to the retention of degradation products. The proposed integrated membrane process with nonporous (deoiling) and nanofiltration (solvent recovery) membranes could be an attractive preposition besides being an acetone free process.     

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%.     

Micellar-Enhanced Ultrafiltration of Heavy Metals Using Lecithin

Abstract

Conventional treatment methods for removal of heavy metals from metal finishing operations are usually energy-intensive and costly. Micellar-enhanced ultrafiltration (MEUF) with synthetic surfactants is a recently developed technique which can remove heavy metals and other small molecular weight ions from wastestreams at relatively lower costs and without a phase change. Lecithin, a natural, inexpensive, nontoxic, and biodegradable surfactant exhibits emulsifying characteristics which can be used in a MEUF. The binding of various lecithins to cadmium, copper, lead, nickel, and zinc—in a mixture and individually—was studied using a continuous diafiltration method. This technique uses small volumes of toxic waters and produces an entire isotherm with just one experiment. In the presence of all five heavy metals, the lecithin in this study showed the following affinity: Cu > Cd ～ Zn > Ni. In experiments when only one metal was present, lecithin exhibited the following affinity: Ni > Cu ～ Zn > Cd. Lead was not bound significantly in either scenario.     

海工水泥的特性和生产技术要求

在海洋工程中,混凝土的耐久性因为海水中氯离子的侵蚀而受到严重危害。因此,提高水泥的抗海水侵蚀性能,是提高海工混凝土耐久性和延长海工混凝土使用寿命的最佳途径。通过优化水泥中熟料和特殊活性材料的组分,确保各组成材产的质量品质满足相关标准,由此生产的具有抗氯盐功能的海工水泥,能够满足海港工程的结构防腐蚀和耐久性能要求。     

The production and properties of oriented polypropylene laminates

The mechanical properties of isotactic polypropylene can be enhanced in one direction by a combination of rolling and drawing in a rolling mill. The longitudinal strength and modulus of the oriented polypropylene (OPP) increases with an increase in draw ratio; however, the transverse properties remain relatively unchanged. In this study, multidirectional OPP laminates [with (0)₂, (0/90)_s and (0/±45)_s lay-ups] were made to obtain sheet materials with improved properties in more than one direction in the plane. A hot-plate welding technique was used to produce these translucent and recyclable laminates. The in-plane properties of the laminates were successfully predicted with classical laminate theory (CLT), which is commonly used to predict the properties of fiber reinforced materials. These laminates can be quasi-isotropic and were found to have improved modulus [up to 6 GPa for (0/90)_s laminates] and strength [up to 150 MPa for (0/90)_s laminates] as well as exceptionally good impact toughness.