水相体系磷脂酶A1改性蛋黄卵磷脂的研究

为了提高蛋黄卵磷脂的乳化性,采用水相体系磷脂酶A1(PLA1)对蛋黄卵磷脂进行酶解改性,并对影响磷脂酶A1水解过程的各个因素进行研究。建立温度、酶底比及底物浓度3因素与酶解液AV值关系的数学模型,并利用响应面法优化出蛋黄卵磷脂酶解改性的适宜条件:温度45℃、酶底比25:1 LU/g、底物浓度30%。该条件下制备的蛋黄卵磷脂酶解液AV值为66.798mgKOH/g,其乳化活性和乳化稳定性与未改性的蛋黄卵磷脂相比较,分别提高了1.05倍和2.18倍。     

磷脂酶A1水解蛋黄卵磷脂的研究

采用磷脂酶A1水解蛋黄卵磷脂,通过单因素实验和正交实验确定该酶水解蛋黄卵磷脂经济合理的工艺条件为：反应温度50℃,反应时间5h,加酶量0．40 IU／g,起始pH6．0,底物质量浓度80g／L;利用电喷雾飞行时间质谱仪分析水解前后蛋黄卵磷脂组分,磷脂酶A1水解Sn-1位脂肪酸,生成含Sn-2位不饱和脂肪酸的溶血磷脂,反应过程中有酰基位移发生。     

磷脂酶A_2水解蛋黄磷脂工艺及改性蛋黄性质的研究

研究磷脂酶A2水解蛋黄卵磷脂的工艺及产品的功能性质。得到最佳工艺条件为：不需要外加Ca^2＋,pH7．0,反应温度为50℃,加酶量为2000 U／g蛋黄,反应时间为1．5h,得到磷脂的水解率约为80％。功能性质表明,与普通蛋黄相比,改性蛋黄具有更好的乳化稳定性,乳化容量提高了近25％;改性蛋黄制作的蛋黄酱经受100℃,30min热处理不会有油析出,普通蛋黄制作的蛋黄酱几乎全部破乳。     

磷脂酶修饰提高蛋黄磷脂乳化性及稳定性的研究

鸡蛋蛋黄在食品加工中经高温处理乳化性会显著下降,用磷脂酶修饰蛋黄磷脂,将其转变为溶血磷脂,使改性后的蛋黄在高温、低pH、高离子浓度环境下仍具有良好的乳化性及稳定性.本试验研究了磷脂酶修饰后蛋黄粉的乳化性和热稳定性.结果表明:改性蛋黄粉的乳化性、热稳定性都有显著提高.与普通蛋黄粉相比,改性蛋黄粉具有较强的抗酸、抗碱能力,乳化性提高了30%,且乳化稳定性是普通蛋黄粉的4倍.通过差示扫描量热仪(DSC)分析可知,改性蛋黄的变性温度高达95℃,显示出很强的耐热性.     

日本推出2种新型食品酶制剂

日本有2家公司先后研制成功“磷脂酶A2”和“反式谷氨酰胺酶TG-YG”，并正式推向市场。磷脂酶A2是可以将蛋黄和大豆卵磷脂转化为溶血卵磷脂的水解酶。其商品名为“溶血磷脂酶”，单位活性达到1万U。同时，其理化性状，最适pH值等也同磷脂酶完全一致，在市场价格上也同磷脂酶流通市场价基本相同。由于溶血卵磷脂酶是以日本产猪胰脏为原料并且在达到药品生产的GMP要求的工厂内生产的，不存在安全问题。     

不同磷脂成分的研究及其乳化能力的比较

目的:对不同磷脂的组成成分和脂肪酸比例进行研究,比较不同磷脂在乳剂中的乳化能力。方法:采用《中国药典》中蛋黄卵磷脂(供注射用)的磷脂酰胆碱、磷脂酰乙醇胺和有关物质含量的测定方法,分别测定大豆卵磷脂、蛋黄卵磷脂以及蛋黄磷脂酰胆碱中的磷脂酰胆碱(PC)、磷脂酰乙醇胺(PE)、溶血磷脂酰胆碱(LPC)、溶血磷脂酰乙醇胺(LPE)、磷脂酰肌醇(PI)、鞘磷脂(SM)的含量;采用气相色谱法对大豆卵磷脂、蛋黄卵磷脂、蛋黄磷脂酰胆碱中主要的脂肪酸进行含量测定;分别采用大豆卵磷脂、蛋黄卵磷脂和蛋黄磷脂酰胆碱作为乳化剂进行脂肪乳的制备,以脂肪乳的平均粒径、粒径分布、D_(90)值、ζ电位和表面张力作为考察指标,对3种不同磷脂的乳化能力进行综合评价。结果:大豆卵磷脂、蛋黄卵磷脂、蛋黄磷脂酰胆碱中成分组成,脂肪酸组成及比例均有明显差异;采用大豆卵磷脂、蛋黄卵磷脂、蛋黄磷脂酰胆碱作为乳化剂制备的乳剂的物理稳定性也有显著差异。结论:大豆卵磷脂、蛋黄卵磷脂以及蛋黄磷脂酰胆碱由于其来源和制备工艺不同,使得其各自的成分和脂肪酸组成不一致,组成成分和脂肪酸的差异进一步导致了其乳化能力有所差异。     

磷脂酶A改性的蛋黄功能性质及其对蛋制品品质影响

采用磷脂酶A水解蛋黄中的卵磷脂生成溶血卵磷脂，转化度为80％。研究了磷脂酶A改性蛋黄的功能性质及其对蛋黄酱和面包品质的影响。改性蛋黄功能性实验表明：酶法改性之后的蛋黄比普通蛋黄具有更大的乳化稳定性、吸湿性，以及显著的耐热性。蛋黄酱应用实验表明：相对普通蛋黄制作的蛋黄酱，酶法改性的蛋黄制作的蛋黄酱黏度是其1．5倍，而且改性蛋黄制作的蛋黄酱可经受100℃，30min的热处理而不会有油析出。面包应用实验表明：改性蛋黄制作的面包具有更高的综合评分，比普通蛋黄对面包具有更好的抗老化效果。     

高效快速提取蛋黄卵磷脂的新方法

０前言卵磷脂是磷脂酸的衍生物 ,别名为磷脂酰胆碱。因其磷酸上的Ｈ 和胆碱上的ＯＨ -皆可解离 ,所以呈两性、磷酸、胆碱、不离解的甘油均有亲水性 ,故卵磷脂具有良好的乳化性能 ,因而为食品和医药界广为利用。蛋黄卵磷脂以其乳化特性和安全性 ,被用在生产人工血浆、脂乳剂和ＶＥ 上 ,在临床上更为重要的用途是 :可用于治疗动脉粥样硬化、脂肪肝、神经衰弱、营养不良及静脉注射脂肪乳的乳化剂、胆固醇结石的防治药物。因此 ,研究和探索安全性能稳定的蛋黄卵磷脂的制造方法 ,将有利于推动这些产业迅速发展 ,将有利于对当前多发病、疑难病的…     

己烷体系中磷脂酶A1催化卵磷脂乙醇解制备溶血卵磷脂的研究

在己烷体系中,采用磷脂酶A1催化卵磷脂乙醇解制备溶血卵磷脂。首先通过单因素试验分别考察了加酶量、加水量、底物比、温度和溶剂比对卵磷脂乙醇解制备溶血卵磷脂的影响,并在此基础上利用响应面法对反应工艺进行了优化。最终确定最佳工艺条件为:卵磷脂1.5 g,加酶量40μL/g(磷脂酶A1/卵磷脂),加水量25μL/g(水/卵磷脂(PC)),底物比:1∶3(PC/无水乙醇,mol/mol),温度30℃,溶剂比:1∶2(PC/正己烷,W/V),反应时间3.55 h,溶血磷脂转化率达98.3%。结果表明,磷脂酶A1可以催化磷脂酰胆碱乙醇解反应制备溶血磷脂酰胆碱。     

大豆蛋白-磷脂酶解物共建乳化体系性质研究

通过对大豆分离蛋白-磷脂酶解产物乳状体系的共建,探究不同磷脂酶A1,A2,C,D酶解磷脂对乳化体系乳化性质的影响,测定添加不同磷脂酶解产物后蛋白乳化体系的可溶性蛋白含量、乳化活性、乳化稳定性、乳层析指数、Zeta电位、粒径分布、光学显微镜的变化。结果表明,磷脂酶解产物与大豆分离蛋白有明显的交互作用,其中磷脂经磷脂酶A2酶解后的产物与大豆分离蛋白共建的乳化体系,在乳化活性、稳定性、粒径分布、Zeta电位、显微结构方面均好于其它复合体系。其乳化活性提高10.17 m2/g,稳定性提高25.2%,负Zeta电位绝对值增加5.09 m V,乳状液平均粒径明显变小,显微结构乳滴分布均匀。这表明经磷脂酶A2酶解后的磷脂非极性基团减少,亲水性增强,与蛋白交互作用增强,使蛋白更好的结合到磷脂的片层结构中,改变复合物结构,促进乳化体系稳定。     

Oil-in-water emulsion properties of egg yolk: Effect of enzymatic modification by phospholipase A2

Emulsifying properties of egg yolk were investigated after a treatment with phospholipase A₂ (PLA₂) where phospholipids (PLs) are converted into lyso-phospholipids. The resulting lyso-PLs are more hydrophilic and therefore show improved emulsifying activity in o/w-emulsions. However, so far no systematic study deals with the changes of egg yolk's functionality due to enzymatic treatment. Little is known about the emulsion properties particularly in different environmental conditions. Egg yolk's functional behaviour is highly dependent on pH and salt concentration used. Therefore, this study investigated four different environmental conditions. At pH 4 the pH of commercial dressings is simulated and pH 6.5 represents the pH of untreated egg yolk in its natural form. Two salt concentrations are used, where granules are in their native and their disrupted form, i.e. 0.15 and 0.52 M NaCl, respectively. Results suggest that significant differences in the emulsifying properties of untreated and modified egg yolk not primarily derive from the existence of lyso-phospholipids but from structural changes in egg yolk granules and LDL micelles.     

Emulsifying Properties of Low-fat, Low-cholesterol Egg Yolk Prepared by Supercritical CO2 Extraction

Comparisons were made with native egg yolk, dried egg yolk and a commercial yolk substitute (soy lecithin). Aqueous emulsions were prepared by sonicating water containing 0–5% NaCl, 20% peanut oil, HC1 or NaOH as needed for pH adjustment, and 1–3% emulsifier expressed as the total of phospholipids, glycolipids and proteins contributed by yolk ingredients or soy lecithin. The median diameters of fat particles in the emulsions with and without dispersing fat droplet floes using Triton X-100, were evaluated by laser light diffraction. The emulsifying properties of low-fat, low-cholesterol egg yolk were similar to or better than those of native yolk and dried egg yolk. Soy lecithin had less effective emulsifying properties than yolk ingredients with respect to coalescence of fat droplets during storage and separation during 70°C treatment.     

Egg yolk: structures,functionalities and processes

Hen egg yolk is an ideal example of natural supramolecular assemblies of lipids and proteins with different organization levels. These assemblies are mainly due to interactions between proteins and phospholipids, and these interactions are essential in understanding and controlling the production of food made with yolk, and particularly emulsions. Furthermore, these assemblies can be modulated by external constraints among which thermo‐mechanical and high‐pressure treatments. This review focuses on multi‐scale structures present in egg yolk, and their modulation by processes, in relation with their emulsifying properties. Egg yolk is mainly composed of two fractions—plasma and granules—which are natural nano‐ and micro‐assemblies. These two fractions possess different composition, structures and functionalities and exhibit specific behaviour under treatments such as high pressure and temperature. Plasma contains a large quantity of lipids structured as lipoproteins (low‐density lipoproteins), whereas granules are mainly composed of proteins aggregated in micrometric assemblies. If plasma is responsible for the important emulsifying properties of yolk, granules bring interesting emulsifying properties when assemblies are in the form of micelles in presence of salts. High‐pressure or thermal treatments, applied before or after emulsion fabrication, alter their functionalities and could be used to commercially exploit these fractions. © 2013 Society of Chemical Industry     

热处理对酶改性蛋黄液乳化性的影响及拉曼光谱分析

蛋黄液对热敏感,64 ℃左右开始变性形成凝胶,加工过程中的热处理会导致其乳化性质下降,限制了其在食品工业中的应用。因此,本实验研究不同热处理条件（60、65、70 ℃均处理4 min）对酶改性蛋黄液乳化性质及蛋白质结构的影响。结果表明：随着热处理温度的升高,蛋黄液的乳化活性呈现下降的趋势,所形成的乳化体系平均粒径表现出增大的趋势。同一热处理条件下,酶改性蛋黄液的乳化活性及乳化稳定性均显著高于未改性蛋黄液（P＜0.05）,酶改性蛋黄液所形成的乳化体系粒径明显减小,粒径分布更加接近正态分布。拉曼光谱分析结果显示,在不同热处理条件下酶改性蛋黄液中蛋白质二级结构发生变化,在65 ℃以下随温度升高α-螺旋结构相对含量显著升高,无规卷曲结构相对含量显著下降（P＜0.05）;其色氨酸残基、酪氨酸残基及脂肪族疏水基团较未改性蛋黄液更倾向于暴露。采用偏最小二乘法建立了基于拉曼光谱的蛋黄液乳化性质模型,结果表明蛋黄液中蛋白质二级结构及构象变化（特别是低密度脂蛋白的构象变化）对蛋黄液乳化性质影响最大。     

Emulsifying characterization of hens egg yolk proteins in oil-in-water emulsions

Emulsifying properties of egg yolk as a function of pH and oil volume were studied. Egg yolk proteins formed larger emulsion particles at pH 3 and the mean droplet size of the emulsions was decreased with increasing pH. A linear relationship between turbidity and mean droplet size of egg yolk emulsions could not be obtained. This may be due to the floculation of the emulsions. Egg yolk proteins formed thicker multilayers at low oil volume, however total protein adsorption ratio against original proteins was 55–65%, independent to protein and oil concentration. Electrophoretic analysis of the egg yolk emulsion revealed that the main components to adsorb at the interface was glanular lipovitellins, even though its emulsifying property was lower than that of plasma because of poor solubility at low ionic strength (0.1 M NaCl) at pH 7. These results indicate that the main contributor for egg yolk emulsion is granules and it can affect the emulsifying properties of egg yolk at different pH values.     

物理、化学、生物法处理蛋黄颗粒对其乳化特性影响的研究进展

蛋黄颗粒（Egg Yolk Granules, EYGs）是蛋黄经过稀释离心后的沉淀部分,因其主要成分为脂蛋白,所以具有一定的乳化性能。天然颗粒的乳化性能由于其内部结构的影响,乳化性能较差,但经过不同方式处理后可使其乳化性能得到明显改善。然而到目前为止,关于蛋黄颗粒乳化性能的改善方式和效果等仍缺乏深入探讨和系统总结。基于此,该研究综述了几种较为广泛的处理方式,包括机械处理、加热处理、外源添加处理、化学处理和酶法处理等对蛋黄颗粒乳化性和乳化稳定性的改善效果,发现大部分方法均可不同程度增强蛋黄颗粒的乳化性或乳化稳定性,且作用机制不尽相同。该研究阐述了各种处理方式对蛋黄颗粒结构、乳化性能的影响及其作用机制,为改善蛋黄颗粒乳化性能、明确作用机理提供了理论参考。同时,对蛋黄颗粒的发展方向提出展望,以期提高蛋黄颗粒在未来食品领域中的应用价值。     

Isolation of Egg Yolk Granules as Low‐Cholesterol Emulsifying Agent in Mayonnaise

Egg yolk is an essential ingredient for many food products due to its excellent functional properties such as emulsification. However, the consumers’ concern of its cholesterol level has led food industry to seek solutions for its replacement. Utilization of low‐fat egg yolk granules as emulsifier can be an alternative strategy. In this study, granules with low cholesterol content were separated from egg yolk by a simple method under easily scalable centrifugal conditions. The egg yolk granules isolated within 0.17 M NaCl solution achieved a 22.5% yield that was similar to that using higher centrifugation speeds and longer time. The yield of egg yolk granules increased from 25% to 32% when the yolk:water ratio was changed from 1:1 to 1:2. Mayonnaise was prepared to evaluate the emulsifying capacity of the egg yolk granules. It was found that egg yolk granules exhibited similar emulsifying activity as that of whole egg yolk, but a better emulsion stabilizing property that is evidenced by the higher viscosity of mayonnaise prepared with the granules. In addition, the viscosities of mayonnaise prepared by spray dried yolk and granules were slightly higher than the liquid counterpart, showing a further improvement by spray drying on the emulsion stabilizing properties. The mechanical spectra of mayonnaise samples by frequency sweep also suggested that granules favored the formation of stronger 3‐dimensional arrangements of oil droplets and therefore a more stable emulsion. Results suggest that granules isolated within 0.17 M NaCl solution present best emulsifying properties and can be applied as whole yolk replacer in food emulsions.     

Production of phospholipids from spray-dried egg yolk by consecutive in situ solid phase extraction with acetone and ethanol

Egg yolk lipids were extracted and fractionated into neutral lipids and phospholipids using acetone followed by ethanol as eluting solvents to a column consisting of spray-dried egg yolk. This technique, named in situ solid phase extraction, can be performed with spray-dried egg yolk due to the properties of this material. The effect of temperature, flowrate and scale has been studied. Results suggest that the methodology is suitable for industrial implementation.     

鸡蛋黄中天然活性物质的开发与利用

鸡蛋中蛋白质、脂类、碳水化合物、维生素、矿物质等营养成分含量丰富,是人类饮食的重要组成部分。鸡蛋黄中的蛋黄油、卵磷脂、卵黄高磷蛋白、免疫球蛋白等多种成分具有抑菌、抗氧化、提高免疫力、消炎、防癌等生理功能。目前,蛋黄中生物活性成分及其生产新技术的开发已经成为国内外研究的热点,部分成果已经实现了商业化应用。如何充分利用蛋中的活性物质并将其开发成具有治疗、保健功能的原料是蛋品科学与加工技术研究的一个主要课题。本文以蛋黄油、卵磷脂、卵黄高磷蛋白、免疫球蛋白4种物质的开发为主线,就鸡蛋黄中天然活性物质的含义、制备方法、生理功能、开发利用情况进行综述,以期为蛋黄中活性物质的进一步研究开发提供参考。