钻井过程中水合物层化学稳定实验研究

油田试验显示,钻井液中加入Lecithin可稳定北极Cascade地区水合物层。针对这一现象开展了一系列实验研究。通过特制的实验装置,对加入不同含量Lecithin后钻井液Ⅰ、Ⅱ、Ⅲ(或加入部分水)体系中甲烷水合物形成的热力学条件和甲烷水合物的生成速度与数量进行了测定。实验结果表明:Lecithin的加入基本上不影响钻井液中甲烷水合物形成的热力学条件;对于钻井液Ⅰ和钻井液Ⅲ的实验流体体系,Lecithin是很好的甲烷水合物生成促进剂。     

Physical Properties of Soybean Oleogels and Oil Migration Evaluation in Model Praline System

The present study examined the physical properties of soybean oleogels and commercial confectionery filling fats and evaluated the oil migration properties in model praline systems. Soybean oleogels were prepared using different oleogelators namely monoglyceride (MAG oleogels) and a mixture of sorbitan tri‐stearate (STS) with lecithin (50:50) (Lec‐STS oleogels). Both MAG oleogels and Lec‐STS oleogels demonstrated a flat solid fat content (SFC) profile with zero SFC at 40 °C. At low temperature, MAG oleogels and Lec‐STS oleogels demonstrated a non‐flowing gel‐like property due to the ability of the oleogelator to entrap liquid oil. In addition, oleogels also showed thixotropic behavior indicating the possible capability to prevent migration of filling fats to coatings and also good flow ability during pumping though manufacturing equipment. The textural property of oleogels also did not change significantly upon storage indicating good structural stability. When used as in a model praline system, oleogels demonstrated a migration delaying property.     

微波辅助浸提鱼鳞卵磷脂的工艺研究

通过单因素试验,研究了乙醇体积分数、乙醇用量、提取时间、微波功率对鱼鳞卵磷脂提取量的影响规律,采用正交试验,得出了鱼鳞卵磷脂提取工艺的最佳参数组合为:乙醇体积分数95%、乙醇用量50mL/g、提取时间4min、功率240W。在此条件下每克鱼鳞中可提取卵磷脂23.87mg。     

Lipoprotein Subfraction Profile and HDL-Associated Enzymes in Sickle Cell Disease Patients

Although hypocholesterolemia is a reported finding in sickle cell disease (SCD), low-density lipoprotein (LDL)/high-density lipoprotein (HDL) subfractions and HDL-associated enzymes have not been determined in SCD patients. Blood was collected from 38 hemoglobin (Hb)A volunteers and 45 homozygous HbSS patients who had not received blood transfusions in the last 3 months. Serum lipids were measured by automated analyzer while LDL and HDL subfraction analysis was done by continuous disc polyacrylamide gel electrophoresis. Serum levels of cholesteryl ester transfer protein (CETP), lecithin-cholesterol acyltransferase (LCAT), apolipoprotein B (apoB) and apolipoprotein A-1 (apoA-I) were determined by enzyme-linked immunosorbent assay (ELISA). Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) levels were significantly decreased, while TG levels were significantly increased in SCD patients compared to controls. A significant decrease in intermediate-density lipoprotein (IDL)-C, IDL-B, IDL-A and LDL-1 fractions were seen in SCD patients, while no significant difference was observed in small dense LDL particles. A significant decrease was seen in HDL-large, HDL-intermediate and HDL-small fractions in SCD patients versus controls. Levels of LCAT and ApoA-1 protein measured in SCD patients were significantly lower while no significant difference was observed in CETP and ApoB protein levels compared to controls. The reduction observed in LDL- and HDL-C in SCD patients was reflected as significantly decreased IDL, LDL-1 and HDL-subfractions. Decreased HDL subfractions may possibly lead to the reduced ApoA-1 and LCAT protein levels observed in SCD patients.     

Influence of Individual Phospholipids on the Physical Properties of Oil-Based Suspensions

The impact of soybean lecithin and three individual phospholipids at different concentration (C_PL) on rheology and sedimentation behavior of sugar/soybean oil suspensions (? = 0.31) was studied and compared with attraction and retraction forces between sugar surfaces in soybean oil as measured by atomic force microscopy (AFM). In general, a surfactant‐induced reduction of yield stress, apparent viscosity and sediment volume of the suspensions coincides with a decrease of adhesive interactions between sugar particles in soybean oil. Although the general influence of individual phospholipids and soybean lecithin is comparable, it is concluded from investigations at low C_PL that individual phospholipids exhibit a less pronounced impact on the analyzed parameters. Furthermore, at low C_PL, binary mixtures of the phospholipids are more efficient than individual phospholipids as regards the reduction of yield stress and sediment volume. While the same tendency was detectable for AFM results, these differences were not statistically verified. Slight differences were also evident when comparing individual phospholipids and their influence on rheology and sedimentation which are, however, not in line with the results of AFM. A general understanding of these interrelations between surfactant composition and possible synergistic or antagonistic effects in mixtures of individual phospholipids contributes to optimizing lecithin composition with respect to functionality.     

An aqueous suspension system for phospholipase D-mediated synthesis of PS without toxic organic solvent

Enzymatic synthesis of PS by phospholipase D (PLD)-mediated transphosphatidylation in an aqueous media was investigated. The purpose of this study was to establish a novel synthetic method where no toxic organic solvents were used. An attempt to react soybean lecithin (simply dispersed in an aqueous buffer) with an aqueous solution of l-serine and PLD was unsuccessful, giving only 20% of PS. By contrast, a suspension of lecithin adsorbed on fine powders such as silica was effectively converted into PS in an aqueous solution of l-serine and PLD. After screening various powders for use as the lecithin adsorbent, calcium sulfate was found to be the best with respect to lecithin conversion. In addition, calcium sulfate did not require prior adsorption of lecithin (i.e., the reaction proceeded effectively simply by adding the powder to an aqueous mixture of lecithin, l-serine, and PLD). With this “aqueous suspension system” of calcium sulfate, up to 180 mg/mL lecithin was completely converted, resulting in more than 80% PS in 24 h. The synthesized PS could easily be recovered from the powder by extracting with a mixture of n-hexane, ethanol, and diluted HCl.     

蜂胶在食用油脂中的抗氧化作用

本文以猪油、菜油为实验材料,测定其POV值来评价蜂胶在动物油和植物油中的抗氧化特性,并与没食子酸丙酯(PG)比较.结果表明蜂胶能够延缓这些底物的氧化进程,明显延长诱导期.且柠檬酸、卵磷脂能增强其抗氧化功能.蜂胶的抗氧化能力强于相近浓度的PG,蜂胶在短时间高温加热后,其抗氧化效率不受影响.     

Emulsifier type,metal chelation and pH affect oxidative stability of n‐3‐enriched emulsions

Recent research has shown that the oxidative stability of oil‐in‐water emulsions is affected by the type of surfactant used as emulsifier. The aim of this study was to evaluate the effect of real food emulsifiers as well as metal chelation by EDTA and pH on the oxidative stability of a 10% n‐3‐enriched oil‐in‐water emulsion. The selected food emulsifiers were Tween 80, Citrem, sodium caseinate and lecithin. Lipid oxidation was evaluated by determination of peroxide values and secondary volatile oxidation products. Moreover, the zeta potential and the droplet sizes were determined. Tween resulted in the least oxidatively stable emulsions, followed by Citrem. When iron was present, caseinate‐stabilized emulsions oxidized slower than lecithin emulsions at pH 3, whereas the opposite was the case at pH 7. Oxidation generally progressed faster at pH 3 than at pH 7, irrespective of the addition of iron. EDTA generally reduced oxidation, as evaluated by volatiles formation in all emulsions, irrespective of pH and emulsifier type, except in the lecithin and caseinate emulsions where a pro‐oxidative effect was observed for some volatiles. The different effects of the emulsifier types could be related to their ability to chelate iron, scavenge free radicals, interfere with interactions between the lipid hydroperoxides and iron as well as to form a physical barrier around the oil droplets.     

THE EFFECT OF DRYING AND STORAGE OF SOYBEAN ON THE QUALITY OF BEAN,OIL, AND LECITHIN PRODUCTION

ABSTRACT

A comparative study of soybean drying was carried out between one-stage and two-stage (high–low temperature) drying with shade drying as control. In one-stage drying, the beans were dried at 80, 100, 120, and 140°C, respectively while in two-stage drying, beans were dried at 100, 120, and 140°C in the first stage followed by 80°C in the second stage. The evaluation values after drying showed that high drying temperature caused high skin cracks of the beans. Qualities of extracted crude oil characterized by free fatty acids (FFA), peroxide value (PV), phospholipids (PL) and nonhydratable phospholipids (NHP) were not significantly effected at p<0.05 by different drying methods but NHP had the increasing trend with the drying temperature and two-stage dried beans tended to have NHP higher than one-stage dried beans. The quality of protein in meal determined in terms of protein dispersibility index (PDI) was less than 15% when drying temperature in one-stage drying was higher than 80°C and when the temperature at the first stage of two-stage drying was higher than 100°C. Drying temperature also had the effect on the quality of lecithin when considered in term of the acetone insoluble value (AI). Free fatty acids of extracted crude oil increased when dried beans were stored for two months at 35°C while PL decreased especially in the first month of storage. However, the AI value of lecithin did not change with time.     

大豆卵磷脂的提纯

探讨了以市售大豆油脚为原料,用全溶剂法精制出符合药用规格的大豆卵磷的工艺条件并建立了相应的数学模型。其主要性能指标为：Ｎ％＝１．７０．Ｐ％＝４．０％,酸价１０．４８,碘价９５．３５。