大豆分离蛋白及其制取

综述了大豆分离蛋白的特性和生产现状 ,找出了我国大豆分离蛋白生产与国外先进技术的差距 ,比较了四种大豆分离蛋白的提取方法 ,对大豆分离蛋白的研究和发展方向提出展望     

Incorporated glucosamine adversely affects the emulsifying properties of whey protein isolate polymerized by transglutaminase

Glucosamine (GlcN) and microbial transglutaminase (Tgase) are used separately or together to improve the emulsifying properties of whey protein isolate (WPI). However, little is known about how the emulsifying properties change when GlcN residues are incorporated into WPI cross-linked by Tgase. We used Tgase as a biocatalyst to cross-link WPI in the presence of GlcN in a liquid system for 12 h at a moderate temperature (25°C). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analyses indicated that protein polymerization and GlcN conjugation occurred simultaneously, phenomena also supported by the loss of free amines (9.4–20.5%). Addition of 5 U Tgase/g protein improved the emulsifying properties of moderately cross-linked WPI polymers. The Tgase-treated WPI polymers had a larger particle size (～2.6-fold) than native WPI, which may have reduced coalescence and flocculation in an oil-in-water emulsion system. However, the incorporation of GlcN residues into WPI, predominantly via enzymatic glycation, partly inhibited the cross-links between the WPI molecules catalyzed by Tgase, reducing the size of the WPI polymers 0.81- to 0.86-fold). Consequently, WPI+GlcN conjugates provided less stability to the emulsion. Moreover, high NaCl concentration (0.2 M) decreased the emulsifying properties of the WPI+GlcN conjugates by neutralizing negative electric charges in the glycoconjugates. However, the improved emulsifying properties of WPI cross-linked by Tgase may be useful in food processing at higher NaCl concentrations due to the formation of the thicker steric barrier at the oil-water interface.     

Impact of whey protein isolates and concentrates on the formation of protein nanoparticles‐stabilised Pickering emulsions

Whey protein nanoparticles (NPs) were prepared by heat‐induced method. The influences of whey protein isolates (WPIs) and concentrates (WPCs) on the formation of NPs were first investigated. Then Pickering emulsions were produced by protein NPs and their properties were evaluated. After heat treatment, WPC NPs showed larger particle size, higher stability against NaCl, lower negative charge and contact angle between air and water. Dispersions of WPC NPs appeared as higher turbidity and viscosity than those of WPI NPs. The interfacial tension of WPC NPs (~7.9 mN/m at 3 wt% NPs) was greatly lower than that of WPI NPs (~12.1 mN/m at 3 wt% NPs). WPC NPs‐stabilised emulsions had smaller particle size and were more homogeneous than WPI NPs‐stabilised emulsions. WPC NPs‐stabilised emulsions had higher stability against NaCl, pH and coalescence during storage.     

不同酶类改性对大豆分离蛋白功能性质的影响

大豆分离蛋白的可控降解可以显著改善其乳化性和起泡性,分别选用来自动物、植物和微生物的胰蛋白酶、木瓜蛋白酶和米曲蛋白酶对大豆分离蛋白进行水解,对其水解程度与乳化性、起泡性和溶解性的关系进行研究。     

不同食用蛋白的添加对鲤鱼鱼糜流变和凝胶特性的影响

目的:研究大豆分离蛋白(soybean protein isolated,SPI)、乳清分离蛋白(whey protein isolate,WPI)、花生分离蛋白(peanut protein isolate,PPI)的添加对鲤鱼鱼糜流变和凝胶性质的影响。方法:利用流变仪、质构仪、色差计等对添加不同蛋白鱼糜的弹性模量、黏性模量、凝胶强度、破断强度、凹陷深度、持水性以及白度进行测定,并采用相关性分析法研究各指标之间的相互关系。结果:不同添加量的SPI、WPI和PPI均能有效地改善鱼糜的弹性模量、黏性模量、破断强度、凝胶强度和持水性,但会降低破断深度和白度,但各测定指标间存在显著相关(p<0.05)。SPI和PPI的添加对鱼糜的流变性、破断强度、凝胶强度的提高效果更好,添加量为8%时,鱼糜的凝胶强度均达到最大值,其中SPI组可达3806.70 g·mm,比对照组增加了34.63%;WPI对鱼糜的保水性效果最好,添加量为8%时,失水率仅为12.6%;白度随着蛋白添加量的增加而降低,其中PPI组与WPI组引起的白度降低较少,且差异不显著(p>0.05)。结论:在实际鱼糜制品的生产中,应根据产品的特征选择适合的蛋白种类和合理的添加量,来提高鱼糜制品的品质。     

美拉德反应对乳清分离蛋白及其水解物抗氧化性的影响

以乳清分离蛋白及其蛋白水解物为原料分别与半乳糖发生美拉德反应,研究两者美拉德反应的褐变程度、接枝度及产物荧光光谱的变化,同时以乳清分离蛋白和蛋白水解物作对照,研究两者美拉德反应产物的抗氧化性。结果表明:乳清分离蛋白及其水解物美拉德反应的褐变程度、接枝度及产物的抗氧化性均在4 h达到最大。其中,乳清分离蛋白及其水解物与半乳糖美拉德反应的褐变程度和接枝度最大值分别为1.114、18.431%和1.413、28.273%;两者美拉德反应产物的还原力、2,2’-联氨-二(3-乙基-苯并噻唑-6-磺酸)二铵盐自由基清除能力和1,1-二苯基-2-三硝基苯肼自由基清除能力分别为0.605、46.29%、61.77%和0.923、69.81%、78.43%,均显著高于对照组(P0.05)。同时,内源荧光光谱发现,美拉德反应改变了乳清分离蛋白及其水解物的构象,使二者的结构更加松散。     

Effect of Spray Nozzle Design on Fish Oil–Whey Protein Microcapsule Properties

Abstract: Microencapsulation improves oxidative stability and shelf life of fish oil. Spray and freeze drying are widely used to produce microcapsules. Newer spray-nozzles utilize multiple fluid channels allowing for mixing of wall and core materials at the point of atomization. Sonic energy has also been employed as a means of atomization. The objective of this study was to examine the effect of nozzle type and design on fish oil encapsulation efficiency and microcapsule properties. A total of 3 nozzle types, a pressure nozzle with 1 liquid channel, a pressure nozzle with 2 liquid channels, and a sonic atomizer with 2 liquid channels were examined for their suitability to encapsulate fish oil in whey protein isolate. Physical and chemical properties of freeze dried microcapsules were compared to those of microcapsules produced by spray drying. The 2-fluid pressure and ultrasonic nozzles had the highest (91.6%) and the lowest microencapsulation efficiencies (76%), respectively. There was no significant difference in bulk density of microcapsules produced by ultrasonic and 3-fluid pressure nozzles. The ultrasonic nozzle showed a significantly narrower particle size distribution than the other nozzles. This study demonstrated that new nozzle designs that eliminate emulsion preparation prior to spray drying can be beneficial for microencapsulation applications. However, there is still a need for research to improve microencapsulation efficiency of multiple channel spray nozzles. Practical Application: Since this research evaluates new spray nozzle designs for oil microencapsulation, the information presented in this article could be an interest to fish oil producers and food industry.     

核桃分离蛋白酶解产物结构与功能的变化

核桃蛋白是优质植物蛋白,但其溶解度较低,限制了其在食品中的应用。为拓宽核桃蛋白的应用范围,采用不同的蛋白酶（碱性蛋白酶、胃蛋白酶、胰蛋白酶、木瓜蛋白酶、中性蛋白酶）对核桃分离蛋白进行酶解,然后分析不同蛋白酶酶解产物的水解度、二级结构和功能性（溶解性、吸水性、吸油性、乳化特性和起泡特性）。结果表明：碱性蛋白酶酶解产物的水解度最高,为22.16%,其次是木瓜蛋白酶的,为20.06%,而胰蛋白酶的最低,为13.95%;FTIR结果显示这5种蛋白酶酶解产物的二级结构中均以β-折叠及β-转角为主;在pH 7.0时,与核桃分离蛋白的吸水性（2.36 g/g）和吸油性（4.65 g/g）相比,5种蛋白酶酶解产物的吸水性和吸油性分别提高了11.58～17.15 g/g和7.58～15.44 g/g;与核桃分离蛋白相比,在不同pH（2～12）下,5种蛋白酶酶解产物的溶解度显著提高;在不同的pH和NaCl浓度下,5种蛋白酶酶解产物的乳化特性和起泡特性也不同。从提高蛋白功能性角度考虑,碱性蛋白酶为核桃分离蛋白的最佳酶解用酶。     

Proteose Peptones and Physical Factors Affect Foaming Properties of Whey Protein Isolate

Effects of peptides and nonprotein components of whey on whey protein isolate (WPI) were studied using a differential pressure method. Decay of WPI foam followed biphasic first-order kinetics, but was affected by solution conditions. WPI foam stability exhibited two pH optima (5.0 and 8.5). Addition of 0.02–0.15M NaCl progressively decreased foaming capacity and foam stability. Addition of 0.01–0.2% proteose-peptones caused a sharp decrease in foam stability, but did not affect WPI foaming capacity. Foam stability was increased by addition of up to 20% lactose. Removal of proteose-peptones should greatly improve foaming properties of whey proteins.