蛋清蛋白质热处理改性及其热聚集行为的研究进展

蛋清蛋白质的热处理改性有助于提高其功能特性及生物有效利用率,从而拓宽其在食品工业中作为配料的应用范围。热处理主要通过对蛋清蛋白质热聚集行为的影响,从而影响其在食品体系中的应用,而对蛋白质聚集行为的研究将有助于改善食品体系中蛋白质的功能性质。蛋清粉是许多食品加工中的重要原料,也是很好的蛋白质体系,是食品蛋白质热聚集行为和功能性构效关系的理想研究对象。对蛋清蛋白质聚集机制的研究将有助于功能性蛋制品的开发。因此,本文主要对蛋清蛋白质热聚集行为的研究进行综述,希望能为相关科研人员及企业提供一定的借鉴。     

蛋白质热聚集行为机理及其对蛋白质功能特性影响的研究进展

蛋白质热聚集行为是食品加工过程中较常发生的现象。热处理条件会使蛋白质结构发生变化,引起蛋白质的理化性质的改变,从而导致蛋白质发生热聚集。热聚集体的大小、形态、界面性等直接影响蛋白质凝胶特性、溶解性、起泡性、乳化性等功能特性,从而影响富含蛋白质食品的品质。本文介绍了蛋白质热聚集行为的机理、分类和表征手段,重点综述了蛋白质热聚集行为的影响因素,及蛋白质热聚集行为对蛋白质功能特性的影响,为研究复杂蛋白质体系热聚集行为及对食品品质的影响提供理论基础。     

大豆蛋白的热处理改性及热聚集行为研究进展

大豆蛋白的热处理改性有助于提高其功能特性及生物有效利用率,从而拓宽其在食品工业中作为配料应用的范围。热处理主要通过对大豆蛋白热聚集行为的影响,从而达到影响大豆蛋白功能性质及生物有效利用率的目的。因此,本文拟对大豆蛋白的热处理改性及大豆蛋白(包括大豆分离蛋白、大豆球蛋白及大豆伴球蛋白)的热聚集行为的研究进展进行综述。希望通过对上述方面的综述,能为广大科研人员及企业生产单位提供一定的借鉴。     

利用酪蛋白酸钠的分子伴侣特性抑制蛋清蛋白的热聚集研究

酪蛋白酸钠的分子伴侣作用尚未在蛋清蛋白体系的热聚集研究中应用。通过测定溶液的浊度、上清液总蛋白含量、粒径分布以及分子质量分布变化,研究酪蛋白酸钠添加量对蛋清蛋白热聚集的影响。当酪蛋白酸钠质量浓度为2mg/mL时可以抑制热处理(90℃,30min)蛋清蛋白溶液(5mg/mL)的热聚集,且随着酪蛋白酸钠添加量的增加(2~3mg/mL),其抑制程度增加;当酪蛋白酸钠质量浓度较高时(4~5mg/mL),由于酪蛋白酸钠的溶解性较低,抑制效果无显著变化(P<0.05)。还原SDS-PAGE电泳结果表明,酪蛋白酸钠对蛋清蛋白中的卵白蛋白、卵转铁蛋白热聚集的抑制效果决定了其对蛋清蛋白热聚集抑制效果。随着酪蛋白酸钠添加量的增加,热处理蛋清蛋白溶液中的不溶性聚集逐渐转变为可溶性聚集,结构紧密且体积较大的热聚集体转变为结构疏松体积较小的聚集体。研究结果表明,酪蛋白酸钠的添加可以抑制蛋清蛋白的热聚集。     

食品中蛋白质的重要性

蛋白质是食品中的重要成分。针对食品蛋白质具有多种功能性质以及极高的营养价值,本文阐述了蛋白质在食品中的重要性,描述了蛋白质在不同食品中的功能作用以及与其结构的相互关系;介绍了食品中的主要功能性蛋白质及其在各种食品中的应用;文中对食品蛋白质的主要改性手段进行了介绍。     

3种杀菌方式对蛋清液功能特性及蛋白结构的影响

以蛋清液为研究对象,比较了高密度CO2(DPCD)、脉冲电场(PEF)及热处理等方式对蛋清液功能性质及蛋白结构的影响。结果表明:DPCD处理使蛋清蛋白的溶解度、起泡性及乳化性能大幅降低;PEF处理降低了蛋清蛋白的溶解度,却在不同程度上提高蛋清液的起泡性和乳化性能;热处理提高了蛋清蛋白的溶解度,但降低了蛋清蛋白的起泡性和乳化性能。蛋清液分别经DPCD、PEF和热处理后,蛋清蛋白的结构发生改变,蛋白质部分变性,导致疏水基团外露,表面疏水性有不同程度的增强,其中热处理的影响大,使疏水性跟对照相比提高近1倍。热处理引起的蛋白聚集程度要大于DPCD处理对蛋清蛋白的影响,PEF处理对蛋清蛋白的影响为轻微。综合以上结果,PEF处理的综合效果要好于其他2种处理。     

热改性蛋清粉的贮藏稳定性

为了解热改性蛋清粉的贮藏稳定性,文中对室温贮藏(12个月)的热改性蛋清蛋白功能性和分子特点进行了分析。研究表明:在贮藏期热改性蛋清粉的凝胶性、乳化性、泡沫性都有不同程度的降低,同时疏水性、巯基含量和分子柔性也有明显变化。相关性分析表明:热改性蛋清粉功能性的下降与分子结构的变化显著(P<0.05)相关。蛋白质分子特点是影响热改性蛋清粉的贮藏稳定性主要因素。     

蛋白质与多酚的相互作用在食品运载体系中的研究进展

由蛋白质与多酚相互作用形成的食品运载体系因其良好的生物相容性和抗氧化活性而受到越来越多的的关注。本文主要阐述了蛋白质与多酚相互作用的机制及其复合物的功能特性,重点介绍了蛋白质-多酚运载体系的特性以及其在功能活性物质缓释载体、乳液稳定剂和功能性薄膜中的应用,并基于目前与蛋白质-多酚相互作用有关的食品运载体系形式较少、配合物研究单一以及复合物缺乏安全性评估等问题提出了见解,以期为拓展蛋白质-多酚复合物在食品运载体系中的应用提供参考依据。     

热处理对牦牛乳蛋白稳定性的影响

以牦牛乳为原料,研究其在不同热处理强度下所发生的理化性质及聚集行为,根据SDS-PAGE图谱分析乳蛋白的交联情况,分析乳蛋白的热稳定和热聚集特性。结果表明,热处理导致牦牛乳蛋白变性,发生一定程度的聚集,从而降低体系的稳定性。75℃时聚集物主要是由二硫键作用导致的,温度高于75℃时,巯基-二硫键相互作用逐渐增强,且表面疏水性稳定在较高水平。     

热处理过程中大豆11S球蛋白解离缔合行为研究进展

解离缔合反应是大豆蛋白在外界因素影响下蛋白质分子高级结构发生解聚或聚合的过程,是目前植物蛋白领域研究的热点。通常通过热处理使大豆蛋白发生解离缔合反应而改变其构象从而获得理想功能性质;大豆11S球蛋白是大豆蛋白主要成分之一,因此11S球蛋白的热解离缔合行为一定程度上决定了大豆制品的后期加工特性、品质及其应用范围。本文概述了11S球蛋白基本结构的最新研究进展;基于11S球蛋白热处理过程中蛋白浓度差异引起的体系性状变化,综述了离子强度、pH值、大豆7S球蛋白以及大豆脂蛋白对其解离缔合行为的影响;并分析了相应条件下11S球蛋白解离缔合反应机制,以期阐明在热处理过程中11S球蛋白的解离缔合反应机制,为将大豆蛋白解离缔合反应控制在预期范围内,获得高品质的大豆蛋白食品提供理论依据。     

Influence of atmospheric-pressure cold plasma-induced oxidation on the structure and functional properties of egg white protein

This study examined the effects of atmospheric-pressure cold plasma (ACP) on the structure and functional properties of egg white protein (EWP). Egg white solution was treated with ACP for 0, 10, 20, 30, and 40 min. The structural unfolding of EWP was confirmed as the exposed free SH group content and surface hydrophobicity increased during the 30 min treatment; however, 40 min of ACP treatment showed the opposite tendency, suggesting the formation of protein aggregates. The emulsion stability of egg white emulsions was the highest at 30 min but decreased again at 40 min. In addition, the proportion of large droplets decreased as the treatment time increased up to 30 min. As a result, moderate oxidation was induced during 30 min of ACP treatment, which could contribute to the enhancement of functional properties of EWP. However, excessive oxidation caused by further ACP treatment negatively affected the enhanced functional properties.Industrial relevanceEgg whites are used as functional ingredients for a variety of food products, so the quality and functionality of egg whites can directly affect the productivity of the final products. The present study suggests the moderate oxidation of egg white protein induced by atmospheric-pressure cold plasma, which could contribute to the enhancement of functional properties. These applied studies can serve as a cornerstone for the establishment of advanced oxidation techniques that can enhance the functionality of egg whites without chemical additives, and consequently contribute to the improvement of food quality and productivity.     

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.     

Effects of sucrose and sodium chloride on foaming properties of egg white proteins

Egg white proteins are extensively utilised in the food industry as foaming agents. A number of factors, singly or in combination, can affect the foaming characteristics of egg albumen. In this study, egg white protein solutions heated at various temperatures in the presence of variable concentrations of sucrose and NaCl were whipped for different periods of time. All factors had a significant impact on the foaming properties of egg albumen. Increasing NaCl content and whipping time enhanced protein adsorption at the air–water interface. The presence of sucrose delayed foam formation but contributed to the stability of the aerated system. Controlled denaturation of the protein solutions induced by mild heat treatment enhanced the foaming properties of egg white proteins. This data indicates that the foaming properties of egg white proteins can be manipulated by altering the effect of extrinsic factors in order to achieve optimal formulations for food industrial applications.     

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.     

蛋清蛋白质的糖基化产物结构与凝胶强度关系的探究

鸡蛋清因其良好凝胶性通常以蛋白粉的形式作为食品配料用于肉制品、鱼糜制品等食品中。蛋清蛋白粉凝胶(性)强度主要取决于蛋清蛋白质本身的结构,而专用蛋清蛋白粉的高凝胶(性)强度可通过蛋清蛋白质结构修饰得以实现。前期研究证明,蛋清蛋白质与多糖糖基化接枝改性能够显著提高蛋清蛋白质凝胶性且优于其它改性方法,因此,研究糖基化产物结构与凝胶强度之间的关系,是进一步广泛应用糖基化蛋白的关键因素,也是蛋白质糖基化研究中的新课题。探讨糖基化蛋白质结构与其凝胶性之间的关系,为蛋清卵白蛋白糖基化改性技术工业化应用提供一定的理论基础。     

蛋清蛋白源血管紧张素转化酶抑制肽研究进展

在分析蛋清蛋白的组成及酶解性质的基础上,综述了国外蛋清血管紧张素转化酶抑制肽来源、制备方法、降压活性、酶解动力学、结构修饰和包埋技术的研究现状,并对其在食品、医药领域研究和应用的方向进行了展望。以期为我国蛋清蛋白降压肽的研究与开发提供参考。     

Modification of functional properties of egg‐white proteins

Egg‐white proteins are extensively utilised as food ingredients due to their unique functional properties. Several attempts have been made in order to improve the functional properties of egg‐white proteins and to identify the optimal formulations for unique food products. Experimental data proves that controlled denaturation of egg‐white proteins can have a beneficial impact on various functional applications in the food industry such as emulsifying ability, heat stability, gelation. This review describes the effect of heat‐induced denaturation on protein structure and functionality. Studies on the impact of Maillard reaction, which aim to elucidate the structure‐function relationship of egg‐white proteins, are presented. A novel approach which could be the basis for the development of new methods aiming to improve the functional properties of egg‐white proteins is also discussed.     

低聚糖改性对蛋清蛋白凝胶性影响研究进展

蛋清蛋白是一种营养价值丰富，具有多种功能特性的优质蛋白。低聚糖可通过糖基化反应与蛋清蛋白共价结合，其偶联物的功能特性较天然蛋清蛋白有所改善。文章综述了低聚糖—蛋清蛋白偶联物的凝胶机理，探讨了低聚糖改性蛋清蛋白凝胶的影响因素，梳理了低聚糖对蛋清蛋白功能特性产生的影响，并对低聚糖改性蛋清蛋白的加工应用进行了展望。     

Statistical analysis of effects of industrial processing steps on functional properties of pasteurised liquid egg white

Egg white is widely used as an ingredient in the food industry owing to its excellent functional properties. The transformation of shell eggs into safe liquid, frozen, or spray‐dried egg white with extended shelf life requires many technological operations that result in modifications to the egg white's functional properties. The present study highlights the critical steps affecting foaming and gelling properties during a classical pasteurised liquid egg white process. The main source of variation in functional properties was raw material quality, accounting for 70% of the variability. Part of the remaining 30% was explained by mechanical egg white–yolk separation, tank storage, pasteurisation and homogenisation that resulted in damage to the functional properties, whereas initial flow through pipes and pumping resulted in their improvement. The effects of these steps could be grouped according to the type of treatment undertaken. Dry matter content, pH and treatment intensity at each step contributed about 30% of the variability in functional properties due to processing steps. Relationships between the modifications of egg white functional properties and protein conformation were established. Between 46 and 78% of the variability in functional properties can be explained by protein denaturation, temperature and enthalpy changes. Copyright © 2004 Society of Chemical Industry     

Modifying the Functional Properties of Egg Proteins Using Novel Processing Techniques: A Review

Egg proteins can be used in a wide range of food products, owing to their excellent foaming, emulsifying, and gelling properties. Another important functional property is the susceptibility of egg proteins to enzymatic hydrolysis, as protein digestion is closely related to its nutritional value. These functional properties of egg proteins are likely to be changed during food processing. Conventional thermal processing can easily induce protein denaturation and aggregation and consequently reduce the functionality of egg proteins due to the presence of heat‐labile proteins. Accordingly, there is interest from the food industry in seeking novel nonthermal or low‐thermal techniques that sustain protein functionality. To understand how novel processing techniques, including high hydrostatic pressure, pulsed electric fields, ionizing radiation, ultraviolet light, pulsed light, ultrasound, ozone, and high pressure homogenization, affect protein functionality, this review introduces the mechanisms involved in protein structure modification and describes the structure–functionality relationships. Novel techniques differ in their mechanisms of protein structure modification and some have been shown to improve protein functionality for particular treatment conditions and product forms. Although there is considerable industrial potential for the use of novel techniques, further studies are required to make them a practical reality, as the processing of egg proteins often involves other influencing factors, such as different pH and the presence of other food additives (for example, salts, sugar, and polysaccharides).