糖基化处理对蛋清粉凝胶性与物化特性的影响

为研究糖基化蛋清蛋白质的分子特点,对糖基化蛋清蛋白的凝胶性、巯基数、疏水性、分子柔性和Zeta电位进行测定。结果表明：糖基化改性可使蛋清蛋白质的凝胶强度增加112.51%,持水性增加18.89%。在糖基化反应过程中,蛋清蛋白的构象发生了两方面的变化：一是蛋白质分子部分展开,包含于分子内部的疏水性基团暴露出来,二是蛋白质分子间或分子内形成了二硫键,使总巯基含量下降。此外,糖基化反应使蛋清蛋白的表面游离ε-NH2数目减少,使得蛋清蛋白所带正电荷数减少,从而降低了蛋清蛋白的等电点。     

瓜尔豆胶酶解液改性蛋清蛋白凝胶性质的研究

在最佳酶解条件下酶解瓜尔豆胶,并用HPGFC和HPLC分析酶解液的组成。取酶解液与蛋清蛋白进行接枝改性研究,固定反应温度为60℃,相对湿度为79%,改变底物配比,反应p H值和反应时间,制备不同的接枝产物并研究其凝胶性和持水性。同时,利用氨基酸分析,SDSPAGE分析和凝胶微观结构分析来表征接枝产物的凝胶性能。结果表明:瓜尔豆胶酶解液的主要成分是甘露低聚糖,几乎不含有单糖。为获得最高的凝胶性和持水性,制备接枝产物的最佳反应条件为:底物配比0.5%,p H值9.0,反应时间4 d,此改性蛋白粉在p H 4.0~10.0的范围内有较高的凝胶强度,且具有良好的储藏稳定性。随着改性时间的延长,改性蛋白粉中游离氨基和氨基酸含量减少。SDS-PAGE分析表明,瓜尔豆胶酶解液和蛋清蛋白在接枝反应的过程中,生成了相对分子质量较大的复合物。在SEM下观察,改性蛋白粉所成凝胶的网络结构比原蛋白粉更为紧密均匀。总的来说,瓜尔豆胶酶解液和蛋清蛋白的接枝反应能有效改善蛋清蛋白的凝胶性能。     

蛋白粉增凝的研究进展

本文阐述了国内外改善蛋白粉凝胶性能的一些研究进展,其中蛋清蛋白质的糖基化修饰和酶法交联是两种主要的增进蛋白粉凝胶性能的方法。文章还对高凝胶蛋白粉研究生产的前景和意义做了展望。     

酶法提高蛋清蛋白热稳定性的研究

蛋清蛋白由于蛋清蛋白质自身结构的关系使其具有良好的凝胶性,并且蛋清蛋白粉在加热过程中有利于凝胶性的提高。但超速溶蛋白粉制备过程中要求蛋白粉对热稳定,因此本文通过单因素试验和正交试验选出最优工艺破坏蛋清蛋白质的凝胶性,提高它的热稳定性。通过单因素试验选出最佳水解酶为碱性蛋白酶,水解时底物的最佳浓度为6%。并通过正交试验确定最佳工艺条件为:水解温度50~60℃、水解时间4h、pH值8和加酶量5U/mg。     

糖基化反应对蛋清蛋白质凝胶性的影响

为研究糖基化反应提高蛋清蛋白质凝胶性的机理,利用氨基酸分析仪、苯酚硫酸法、奥氏黏度计、静态激光散射仪对糖基化蛋清蛋白质氨基酸组成、总糖含量、特性黏度、粒径分布进行测定与分析。结果显示：糖基化反应可使蛋清蛋白质的凝胶强度和持水性分别提高91.7%和35.2%,且二者均在反应4d后达到最高值;糖基化处理5d后,蛋清蛋白质的赖氨酸含量相对降低28.42%,总糖含量增至2.18%;特性黏度随反应时间的延长增幅较小;糖基化蛋白粒径分布在0.1～50.0μm之间,糖基化2d内,粒径分布由小粒径峰向大粒径峰转变;糖基化2d后,粒径分布变化不明显。     

大豆-鸡蛋清复合蛋白粉功能性质的研究

本文通过单因素试验设计对大豆分离蛋白-蛋清蛋白混合粉的功能特性进行研究。结果表明,大豆分离蛋白与蛋清蛋白的配比和pH值对实验结果都有显著影响。中性条件下,蛋清蛋白的比例由0%增加到80%时,混合蛋白粉的溶解度由12%上升到58%,凝胶强度由59 g上升到1604 g;大豆分离蛋白的比例由0%增加到80%时,混合蛋白粉的起泡性由86.5%上升到184%,失水率由80%降低为35%。通过实验得出了两种蛋白质之间的非线性作用,两种蛋白质在胶凝性上表现为协同作用,在起泡性上表现为抗拮作用,而在溶解度上二者表现为简单的线性叠加。     

葡萄糖糖基化大豆分离蛋白的凝胶抗冻性研究

为解决大豆蛋白在冷冻食品中因冷冻变性导致功能性下降的问题,本研究对大豆分离蛋白进行了葡萄糖糖基化改性,并分析了改性大豆分离蛋白凝胶的抗冻性变化。结果表明,葡萄糖改性可以提高大豆分离蛋白凝胶的抗冻性,糖基化改性反应条件为蛋白:葡萄糖=2:1、反应pH 7、蛋白含量为40 mg/g。糖基化改性蛋白制备的凝胶在冻藏过程中的蛋白溶解性、亚基及凝胶水分分布等结果显示,改性大豆蛋白凝胶抗冻性的提高是由于糖基化蛋白中葡萄糖分子增强了对水分子的束缚作用从而减少蛋白质的脱水变性,同时,接枝在蛋白链上糖分子的空间位阻作用,阻止了蛋白分子间聚集和新键的形成,维持凝胶的均匀网状结构。     

糖基化凝胶增强剂对鱼糜制品凝胶特性的影响

以新鲜蛋清、刺槐豆胶和瓜尔豆胶为原料,采用湿法糖基化法制备凝胶增强剂,并加入到冷冻鱼糜中,研究糖基化凝胶增强剂对红娘鱼鱼糜制品的凝胶强度、质构、白度、持水性和化学作用力等的影响。结果表明,凝胶增强剂经湿法糖基化改性后可显著提高鱼糜制品的凝胶强度（P＜0.05）。最佳改性条件为反应温度55?℃、加热时间12?h。在此条件下,凝胶增强剂接枝度为（23.37±1.62）%,十二烷基硫酸钠-聚丙烯酰氨凝胶电泳显示蛋白聚集体的形成,表明蛋清蛋白与刺槐豆胶和瓜尔豆胶复配胶显著发生糖基化反应,添加到冷冻鱼糜中可明显改善鱼糜制品的凝胶强度、白度和持水力等。与未添加凝胶增强剂的鱼糜制品相比,凝胶强度提高64%;与添加同等含量的新鲜蛋清的鱼糜制品相比,凝胶强度提高26.9%;与添加未发生糖基化反应的凝胶增强剂的鱼糜制品相比,凝胶强度提高4.7%。实验表明,糖基化改性后的凝胶增强剂具有显著提高鱼糜制品凝胶特性的作用,在鱼糜产业中具有广阔的应用前景。     

提高鸭蛋蛋清蛋白凝胶强度的酰化改性工艺优化

以鸭蛋蛋清蛋白为原料,通过琥珀酸酐酰基化改性以提高鸭蛋蛋清蛋白的凝胶强度。在单因素试验的基础上,选择琥珀酸酐与蛋清蛋白质的添加比例、反应温度、反应时间、反应pH值4个因素为自变量,以蛋白凝胶强度为响应值,进行中心组合试验,建立鸭蛋蛋清蛋白的凝胶强度的二次回归方程,并通过响应面(Box-Behnken)分析,得到优化组合条件。结果表明：经过修正最优工艺为琥珀酸酐与蛋清蛋白质的添加比0.118:1、反应时间35.24min、反应温度22.91℃、反应pH8.09,在此条件下鸭蛋蛋清蛋白的凝胶强度预测值为324.66N,与验证值319.56N接近,优化结果可靠。     

磷酸化改性提高蛋清粉凝胶性的研究

为了提高蛋清粉的凝胶性,文中采用三聚磷酸钠(STP)对蛋清粉蛋白进行磷酸化改性,通过研究三聚磷酸钠添加量、加热时间、温度三因素对蛋清粉凝胶强度的影响,在单因素试验的基础上,采用响应面分析法对改性条件进行优化。结果表明:磷酸化对蛋清粉最适改性条件是STP添加量0.5%,反应温度35℃,反应时间4 h。该条件下生产的蛋清粉与未改性的蛋清粉相比,其凝胶强度由308 g/cm2提高到730.392 g/cm2。     

Modification methods and applications of egg protein gel properties: A review

Egg protein (EP) has a variety of functional properties, such as gelling, foaming, and emulsifying. The gel characteristics provide a foundation for applications in the food industry and research on EP. The proteins denature and aggregate to form a dense three-dimensional gel network structure, with a process influenced by protein concentration, pH, ion type, and strength. In addition, the gelation properties of EP can be altered to varying degrees by applying different treatment conditions to EP. Currently, modification methods for proteins include physical modification (heat-induced denaturation, freeze–thaw modification, high-pressure modification, and ultrasonic modification), chemical modification (glycosylation modification, phosphorylation modification, acylation modification, ethanol modification, polyphenol modification), and biological modification (enzyme modification). Pidan, salted eggs, egg tofu, and other egg products have unique sensory properties, due to the gel properties of EP. In accessions, EP has also been used as a new ingredient in food packaging and biopharmaceuticals due to its gel properties. This review will further promote EP gel research and provide guidance for its full application in many fields.     

不同蛋白粉对南极磷虾混合虾糜凝胶特性的影响

为了提高南极磷虾混合虾糜的凝胶特性,研究大豆分离蛋白粉、分离乳清蛋白粉和蛋清粉对虾糜3D打印特性、凝胶强度、质构特性、持水力、流变学特性、感官特性、热力学特性、蛋白质二级结构含量和微观组织结构的影响。结果表明,三种蛋白粉均能提高混合虾糜的3D打印特性,凝胶强度,弹性模量（G’）和黏性模量（G”）。添加分离乳清蛋白粉虾糜的凝胶强度最高,相比对照组提高了100.15%;添加大豆分离蛋白粉虾糜凝胶的持水力最高,相比对照组提高了20%。差示扫描量热分析（DSC）结果表明蛋白粉的添加可以有效提高混合虾糜凝胶的变性温度和焓值,增强蛋白质的稳定性。扫描电镜结果表明添加蛋白粉虾糜的凝胶网络更加致密,其中添加分离乳清蛋白粉虾糜凝胶的孔洞分布更加均匀。结合感官评定,蛋清粉能够提高南极磷虾混合虾糜的凝胶特性和整体接受度,研究结果可为提升南极磷虾糜及其制品的品质提供理论依据。     

Effects of partial hydrolysis on structure and gelling properties of oat globular proteins

The effects of partial hydrolysis and the environmental conditions (pH and temperature) on the gelling properties of oat protein isolate (OPI) were investigated. OPI was treated with flavourzyme, alcalase, pepsin and trypsin. The changes in protein structure were observed by SDS-PAGE, size exclusion high performance liquid chromatography (SE-HPLC) and amino acid analysis. Gel mechanical properties were evaluated by textural profile analysis (TPA). The results revealed that the acidic polypeptides (12S-A) of oat globulin exerted great influence over the gelling ability of oat protein. Partial hydrolysis by flavourzyme and trypsin could significantly improve oat protein gel strength, especially at pHs 8–9 by modulating the balance between the electrostatically repulsive force and the hydrophobic attractive force among polypeptide chains during the gelling process. The gels prepared with flavourzyme and trypsin treated oat proteins have comparable or higher mechanical strength than soy protein gels at neutral pH. At pH 9 the gel made of trypsin treated oat protein even showed comparable mechanical strength to egg white protein gels under the same pH. Both oat protein and its hydrolysate gel exhibited excellent water-holding capacity at neutral or mildly alkaline conditions. The results of this study indicate that oat protein has a promising potential to be used as new and cost-effective gelling ingredient of plant origin to provide texture and structure in food products.     

Modified soy protein isolate with improved gelling stability by glycosylation under the conditions of ocean shipping

In this study, we modified the soy protein isolate (SPI) by glycosylation technology, tracked and detected its gelling properties in a trial‐box, which simulated the ocean shipping environment, then determined the optimised parameters for glycosylation modification, including humidity, temperature, reaction time, and the amount of polysaccharide added. The gelling stability of the glycosylated SPI increased significantly compared with the non‐modified SPI. The physicochemical properties of glycosylated SPI and non‐modified SPI (degree of glycosylation and sulfhydryl groups) were measured to correlate their effects on the gel strength of glycosylated SPI gels. With an analysis of gel microstructure images measured by a scanning electron microscope, we further verified the formation of the macromolecular complex in glycosylated SPI during glycosylation; the microscopy also revealed a relationship between microstructure and gelling properties of SPI.     

超声协同糖基化对蛋清粉致敏性及结构的影响

以市售蛋清粉为研究对象,通过电泳、紫外光谱、荧光光谱和酶联免疫吸附等方法研究超声波协同糖基化修饰对其蛋白结构和致敏性的影响。结果表明,超声波协同糖基化修饰能显著降低蛋清粉的致敏性,致敏性随超声强度的增加呈先增加后降低的趋势,且在15 min、600 W的条件下有最大程度降低。这和其结构变化密切相关,经复合处理后,蛋清蛋白分子量显著增加,同时三级结构发生显著变化,使表面疏水性增强、内源荧光和自由氨基含量降低,导致其致敏性降低。超声波协同糖基化修饰是一种良好的降低蛋清粉致敏性的方法。     

不同改性方法对蛋清粉致敏性与功能性的影响

本文研究了热处理、糖基化、超声、超声预处理结合糖基化复合改性以及复合改性后再模拟体外消化对蛋清粉致敏性和功能性的影响。结果表明:热处理和超声改性均会增加蛋清粉的致敏性,分别提高了12.77%和20.84%;糖基化改性和复合改性后其致敏性分别降低了29.08%和43.9%,复合改性再模拟体外消化后致敏性进一步降低,最高降低了52.76%。热处理不能有效改善蛋清粉的功能性,而超声可以增强其乳化性能;糖基化后,蛋清粉的溶解性、乳化性能、抗氧化活性等功能性均得到不同程度的改善;复合改性后功能性有了更大提升,并且经消化后抗氧化活性显著增强。这说明复合改性可以更全面显著的改良产品品质,且经人体消化后仍能保持甚至提升。     

Color and gelling properties of dried egg white: Effect of drying methods and storage conditions

Dried egg white is extensively used as a food ingredient due to its unique functional properties and extensive shelf life. This study investigated the effect of drying methods and storage conditions on the color and gelling properties of dried egg white. Egg white was dried with two drying methods; freeze drying and hot-air drying, then stored at 25 and 40°C for 4 months. The result showed that the color of hot-air-dried egg white, especially after storage at 40°C, was darker yellow than for freeze-dried egg whites. The gelling properties of both samples were altered during storage, however, substantial changes in the gelling properties were found in the gel made from stored hot-air-dried egg white. A decrease in the enthalpy of protein denaturation that indicated a partially unfolded protein conformation, an increase in exposed sulfhydryl and a decrease in the total sulfhydryl contents were found, especially in stored samples of hot-air-dried egg whites. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern of proteins in the stored samples showed protein aggregation, and this was related to the increased glass transition temperature. This study revealed that drying egg white using hot-air drying and storage especially at high temperature induced changes in their color and protein conformation. These have contributed to protein aggregation which affected dried egg white’s gel properties.