Emulsification Properties of Succinylated Canola Protein Isolate

Emulsification properties of unmodified and succinylated canola (rapeseed) protein isolate (54 and 84% modification of free amino groups) were examined over a wide range of pH values (pH 3.5–11.0) and sodium chloride concentrations (0.0–0.70M). Both emulsification activity and emulsion stability were increased by succinylation, but extensive succinylation was not required to significantly improve these properties. Multiple regression analyses indicated that emulsification activity was related to protein solubility, hydrophobicity, zeta potential and flow behavior of aqueous dispersions of the proteins. Emulsion stability was affected by protein solubility, zeta potential, apparent viscosity of protein dispersions and difference in density between the aqueous and oil phase.     

Solubility, Hydrophobicity and Net Charge of Succinylated Canola Protein Isolate

Effects of succinylation (54% and 84% modification of free amino groups), pH (3.5–11.0) and NaCl concentration (0.0–0.7M) on solubility, hydrophobicity and zeta potential (net charge) of canola protein isolate were examined. Succinylation markedly enhanced protein solubility at alkaline and slightly acidic pH while effect of NaCl depended on pH. Surface hydrophobicity (S₀) decreased as level of succinylation increased. Effect of NaCl varied with pH but in general, S₀ decreased in a curvilinear manner as pH increased. Zeta potential became more electronegative as both succinylation and pH increased, but decreased with addition of NaCl. Hydrophobicity and zeta potential were closely related in a nonlinear inverse manner demonstrating that ionic environment had opposing influences on number of hydrophobic and charged groups on the surface of protein molecules in solution.     

双低油菜籽分离蛋白提取方法对其功能性的影响

油菜籽蛋白是一种氨基酸组成合理的完全蛋白,其营养价值与酪蛋白不相上下,属于一类潜在的可食用优质蛋白。本文选冷榨油菜籽粕为原料,采用碱溶酸沉和电场絮凝的方法提取其中的油菜籽分离蛋白,并比较其结构和功能性。结果显示:电场方法提取的油菜籽蛋白ERP的表面疏水性为5.776±0.222,大于碱溶酸沉法的样品CRP(4.803±0.060),其乳化性(49.95%)、乳化稳定性(90.85%)及持油性(166.18%)均更优。ERP和CRP分子的二硫键含量分别为47.51 μmol/g和36.67 μmol/g。在电流的作用下,电场提取样品的α-螺旋及β-转角所占比例较高。结论:提取方法会影响油菜籽分离蛋白的氨基酸比例、结构及功能性。     

中性蛋白酶酶解酰化大豆分离蛋白功能特性的研究

利用中性蛋白酶对琥珀酰化大豆分离蛋白进行酶解改性,考察pH值、酶解温度和加酶量对其功能特性的影响,通过单因素和中心组合试验确定最优酶解改性条件:pH值为6.82、酶解温度为48℃、加酶量为6627U/mL。酶解改性后琥珀酰化大豆分离蛋白的功能特性均有较大提高,与改性前的大豆分离蛋白相比溶解度、乳化性、乳化稳定性、起泡性和起泡稳定性分别提高了32.28、3.89、4.41、2.5、1.22倍。     

脱酚及pH偏移处理对菜籽蛋白体外模拟消化的影响

研究了脱酚及pH偏移处理对菜籽蛋白(CPI)及乳液模拟体外消化的影响。采用蛋白凝胶电泳、显微镜观察、粒度分析等方法进行表征。结果表明,在体外消化的过程中,蛋白水解度(DH)整体呈上升趋势,经脱酚、pH偏移及二者协同处理后的DH分别增大了17.1%、2.6%和22.9%。仅脱酚处理使消化产物可溶性蛋白浓度提高了22.3%。SDS-PAGE的结果显示,cruciferin(12S)比napin(2S)更易于水解,并且脱酚导致蛋白在12 kDa以下的条带消失。pH偏移处理显著提高了CPI的自由基清除能力,并改善了由酚的脱除引起的自由基清除能力的降低。对于改性后的蛋白乳液,脱酚导致胃消化阶段更显著的乳液液滴聚集现象,同时降低了肠消化阶段的油滴大小。总的来说,脱酚处理提高了蛋白及乳液的消化率,pH偏移提高了蛋白的自由基清除能力。     

琥珀酰化脱脂豆粕流变性质研究

本文对琥珀酰化脱脂豆粕的流变性质进行了研究.结果表明:琥珀酰化脱脂豆粕溶液的粘度随着酰化程度的增加先增大后减小,均呈现出剪切稀化现象,较未改性脱脂豆粕溶液的粘度均降低.随着琥珀酰化试剂用量的增加,其储能模量(G')和损耗模量(G")的线性范围有所增大;改性脱脂豆粕有着类似的物理凝胶性质.     

Microstructure of Whey Protein Isolate Gels Containing Emulsified Butterfat Droplets

The effects of concentration and droplet size of anhydrous butterfat globules on the microstructure of heat-induced whey protein isolate gels (pH 4.60) were studied by scanning and transmission electron microscopy (TEM). All fat globules were emulsified with whey protein isolate and incorporated into the system prior to gelation. Protein aggregates became more closely packed as whey protein concentration was increased from 8 to 15% by weight in gels without added fat. There was no notable change in overall gel microstructure upon addition of fat globules, up to 25% by weight, when viewed by scanning electron microscopy. However, it appeared fat globules were intimately associated with the gel protein matrix. A twofold difference in fat globule size was obvious by TEM. Clusters of droplets became more predominant as butterfat content increased.     

黄原胶对大豆分离蛋白凝胶流变特性和微观结构的影响

以黄原胶(XG)和大豆分离蛋白(SPI)为试验原料,通过超声波预处理和葡萄糖酸内酯诱导的方式制备XG-SPI复合凝胶,采用流变测试和扫描电镜等方式研究不同浓度XG对SPI凝胶粘弹性能、自修复能力、热稳定性以及微观结构的影响.结果 表明,SPI凝胶是典型的粘弹材料,具有较强的频率依赖性.随着XG浓度(1％～5％)的增加,...     

复合卵白蛋白-大豆分离蛋白对肉糜凝胶特性和微观结构的影响

运用卵白蛋白改善大豆蛋白与肉糜凝胶强度。通过在大豆分离蛋白中添加不同比例的卵白蛋白,应用于肉糜制品中,观察肉糜凝胶理化特性和微观结构,综合分析卵白蛋白和大豆分离蛋白复合凝胶在肉糜制品中的应用效果。结果表明：复合组显著改善产品的硬度、弹性、蒸煮损失、保水性（P＜0.05）,复合蛋白质量比为1∶1时,产品的脂肪聚集体达到最小,硬度得到改善,产品的弹性稳定且达到最大值,产品的可接受度最佳。     

超声波辅助法制备双低菜籽浓缩蛋白工艺研究

该研究以双低菜籽为原料,乙醇溶液为溶剂,在超声波辅助下萃取制备双低菜籽浓缩蛋白;由单因子实验确定最佳工艺参数为:超声频率20DHz,超声功率100 KW,乙醇溶液浓度70％, 液固比3．5:1,萃取3次,每次20 min,得到浓缩蛋白产品蛋白含量大于60％,氨基酸平衡;硫甙、植酸、单宁等杂质去除85％以上。     

Production and Evaluation of Pea Protein Isolate

Laboratory and pilot plant processes were developed for producing pea protein isolate from field peas. Sodium proteinate and isoelectric products containing up to 90% protein were obtained by alkaline extraction and precipitation at the isoelectric point. Drying was carried out by freeze, spray and drum processes. Chemical analysis, functional properties, color and flavor of the dried isolates compared favorably with their soy counterparts. Generally, the sodium proteinates exhibited more functionality than isoelectric isolates. Drum drying decreased the nitrogen solubility index and increased water absorption. Freeze- and spray-drying resulted in isolates with the highest emulsification and water absorption values. Spray drying produced the best foaming, color and flavor properties.     

Films Based on Egg White Protein and Succinylated Casein Cross-Linked with Transglutaminase

Transglutaminase (TGase) and succinylation could modify the physicochemical characteristics and the functional properties of proteins. The aim of this work was to cross-link egg white protein (EWP) and succinylated casein with TGase and to assess the feasibility of making a novel composite protein film. The effects of succinylated casein content, reaction time, and TGase concentration on the mechanical properties, physical characteristics (thermal property and degree of crystallinity), and structure properties (secondary structure and surface micrograph structure) of the film were investigated in this study. The results revealed that the susceptibility of EWP to TGase-mediated cross-linking modification was enhanced by succinylated casein. Meanwhile, the films with TGase were more homogeneous and smoother and possessed better water resistance and thermal stability. The content of α-helix, β-turn structures were increased whereas β-sheet structure was decreased. The spatial conformation and degree of crystallinity of composite protein film were also affected by TGase. The increase of the degree of crystallinity of the composite film further proved the improvement of film mechanical properties induced by TGase and succinylated casein. Based on the above results, this study provides relevant data and insights for the TGase/chemical modification of protein-based edible films.     

Preparation of Functional Soybean Protein Isolate

Soybean protein isolate(SPI) is a high purity soybean protein product.Its protein content is over 90%.A popular processing method is alkali dissolution and acid precipitation.This method can produce various functional SPIs by changing the temperature,pH,types of alkali and acid,and by different pretreatment and post transformation treatment.The properties addressed in this paper would open a big market for the appli cation of SPI.     

功能性大豆分离蛋白的制备

大豆分离蛋白是一种高纯度的大豆蛋白制品,蛋白质含量在９０％以上。目前,国内外生产大豆分离蛋白主要以碱酸沉法为主。它可以控制和改变工艺流程中的温度,ＰＨ酸碱种类,前期处理和后期调整等手段生产功能特性各异的大豆分离蛋白。     

Thermorheological Characteristics of Soybean Protein Isolate

ABSTRACT: Small amplitude oscillation shear measurement was used to study gel rigidity of commercial soy protein isolate (SPI) dispersions during isothermal and non-isothermal heating. Temperature sweep data (20°C to 90°C atheating rate of 1°C/min) of SPI dispersions demonstrated that elastic modulus (G) predominates over viscous component (G') for all concentrations studied. The gelation kinetics of SPI was evaluated by a non-isothermal technique as a function of elastic modulus (G). During experiments, it was observed that a critical concentration of 10% was required to form a true SPI gel. Thermorheological data of 10% and 15% SPI dispersions were adequately fitted by 2nd-order reaction kinetics. The reaction order of gelation was initially calculated by multiple regression technique correlating dG'/dt, G'and temperature, which finally was verified by linear regression of kinetic equation at selected order. Isothermal data of 15% SPI was also followed by 2nd-order reaction kinetics. The activation energy during the isothermal technique was significantly higher than non-isothermal gelation of SPI at same concentration level. Gel strength of the non-isothermally heated SPI sample (15% to 20%) was compared with isothermally heated (90°C for 30 min) one. Higher protein concentration (20%) and isothermal heating exhibited significantly higher gel rigidity while the difference between the 2 processes was insignificant at 15% concentration at a similar condition.     

马铃薯分离蛋白的提取工艺

采用盐溶碱提酸沉法制备马铃薯分离蛋白,并对马铃薯分离蛋白提取条件和功能特性进行研究。十二烷基硫酸钠- 聚丙烯酰胺电泳结果表明,马铃薯分离蛋白的亚基相对分子质量较广,其中分子质量低于21.0kD 的亚基较多。马铃薯分离蛋白的最佳提取工艺为料水比1:10(g/mL)、温度40℃、pH8.0、NaCl 浓度0.4mol/L。     

芋艿分离蛋白质的流变特性

以芋艿分离蛋白为材料,研究了不同pH值环境条件下芋艿分离蛋白的流变特性、紫外和荧光光谱。结果表明：pH值环境对芋艿蛋白的变性及聚集有明显的影响。在pH值接近芋艿蛋白的等电点时,芋艿分离蛋白因聚集导致其表观黏度较高,滞后现象明显,胶凝点温度（Tgel）及凝胶储能模量（G’）较高;当pH值升高至8.0时（大于芋艿蛋白的等电点）,芋艿分离蛋白解聚集,构象展开,表观黏度较低,滞后现象减弱,Tgel及凝胶G’降低。随溶液pH值的升高,频率扫描曲线G’与损耗模量（G”）的交点逐渐向高频方向移动并最终消失。在pH 7.0时,芋艿分离蛋白的紫外吸收峰位于284 nm波长处;其荧光光谱最大激发波长为289.7 nm,最大发射波长为330.3 nm。     

湿热条件下低聚木糖-乳清分离蛋白的美拉德反应及产物乳化性与流变性研究

本文研究了湿热条件下不同混合质量比(1:1、1:2、1:3、1:4,W/W)对低聚木糖与乳清分离蛋白(WPI)美拉德反应及其产物的乳化性与流变性的影响。UV-Vis吸光度值,pH和粒径大小显著变化表明,该条件下成功制备了WPI和低聚木糖的美拉德反应产物 (MRPs)。数据显示,质量比为1:2的溶液体系美拉德反应程度最高;与未经过美拉德反应的体系相比,MRPs的平均粒径均减小而质量比为1:2的体系平均粒径最大;同时,美拉德反应提高了WPI的乳化活性和乳化稳定性,比例为1:2时MRPs具有最佳的乳化活性(38.63 m2/g)和乳化稳定性(65.23%);流变学测试表明糖基化修饰增强了WPI的凝胶性,比例为1:3时MRPs的储存模量提高最大,G''值高达约97,000 Pa (约WPI的7倍);在相同剪切速率下,MRPs溶液的表观粘度增加,而WPI的添加比例对体系粘度的影响占主导作用。上述研究表明,美拉德反应可改善WPI的乳化特性和凝胶特性。     

大豆分离蛋白和谷朊粉复合膜的研究

研究分析了影响大豆分离蛋白和谷朊粉复合膜的成膜因素,及各种因素对复合膜性能的影响.对正交试验结果采用极差分析和综合评分法进行评定,制备综合性能好的可食性膜的最佳条件为:谷朊粉和大豆分离蛋白的比例为1:5,甘油用量为20%,pH值为11,预热处理温度和时间分别为80℃和40min.此时,膜的透光率、拉伸强度、撕裂强度、水分含量和水蒸气透过率依次为60.5%、38.38 MPa、198.02 N/mm、13.87%和0.507(g·mm),(kPa·h·m2).     

大米蛋白乳化性质研究

本文研究了大米分离蛋白(RPI)、酶法大米分离蛋白(E-RPI)、谷蛋白等在不同pH和Na2SO3存在条件下的乳化性能及其表现特点，并与大豆分离蛋白(SPI)的乳化性能进行了比较，结果表明，增加大米蛋白溶解性的措施均有利于改善大米蛋白的乳化性能。谷蛋白一旦溶解其乳化能力与大豆蛋白相当。RPI、E-RPI经Na2SO3处理后，乳化性能明显提高，说明通过解除大米蛋白分子中亚基的聚合，可以改善大米蛋白的物化功能性。