胶凝化工艺对年糕水分分布状态和微观结构的影响

以糊化度、白度值、感官评分、蒸煮特性及质构特性为年糕的品质评价指标,研究胶凝化时间、胶凝化温度及胶凝化湿度对年糕品质的影响,并采用正交试验优化工艺条件.在优化条件下,研究在不同胶凝化时间下,年糕的水分分布和微观结构的变化.结果表明:胶凝化时间、胶凝化温度及胶凝化湿度分别通过影响年糕的胶凝化程度、速率及水分分布,改变年糕...     

肌球蛋白与κ-卡拉胶混合胶凝机理的研究

通过研究pH、离子强度和钾离子对肌球蛋白与卡拉胶混合溶液粘弹性的影响,揭示了肌球蛋白与κ-卡拉胶混合胶凝的机理。肌球蛋白与卡拉胶混合胶凝的过程是肌球蛋白在加热过程中首先胶凝,然后卡拉胶在降温过程中胶凝并使体系胶凝能力增强,卡拉胶的作用一般处于次要地位。较高pH可导致肌球蛋白与卡拉胶混合凝胶能力下降;低离子强度使肌球蛋白与卡拉胶混合胶凝能力明显增强;钾离子促进了卡拉胶的凝胶作用,在肌球蛋白与卡拉胶混合胶凝过程中占主要地位。     

肌球蛋白与k-卡拉胶混合胶凝机理的研究

通过研究pH、离子强度和钾离子对肌球蛋白与卡拉胶混合溶液粘弹性的影响，揭示了肌球蛋白与k-卡拉胶混合胶凝的机理。肌球蛋白与卡拉胶混合胶凝的过程是肌球蛋白在加热过程中首先胶凝，然后卡拉胶在降温过程中胶凝并使体系胶凝能力增强，卡拉胶的作用一般处于次要地位。较高pH可导致肌球蛋白与卡拉胶混合凝胶能力下降；低离子强度使肌球蛋白与卡拉胶混合胶凝能力明显增强；钾离子促进了卡拉胶的凝胶作用，在肌球蛋白与卡拉胶混合胶凝过程中占主要地位。     

冻藏期间蛋黄胶凝化现象及成因分析

蛋黄在－6 ℃以下冷冻贮藏会发生胶凝化现象,影响其在食品加工中的应用。本实验通过流变特性表征了冻藏180 d内蛋黄的胶凝化现象,并进一步通过理化性质、水分分布以及二级结构分析探究蛋黄胶凝化的成因。结果发现冻藏期间蛋黄表观黏度、黏性系数、弹性模量和黏性模量均显著增加,而流动指数和损耗角正切值显著减小,表明冷冻导致了蛋黄严重的胶凝化。平均粒径的增加、表面疏水性的增强、总巯基含量的下降、蛋黄水分分布的变化尤其是可冻结水含量的减少,都会导致蛋黄胶凝化;同时蛋黄蛋白质二级结构从无序向有序转变,也促进了蛋黄蛋白质的聚集,进一步诱导蛋黄胶凝化。本研究探究蛋黄胶凝化的原因,为进一步改善蛋黄在冷冻过程中出现胶凝化提供参考。     

酸奶凝胶的组织特性与物理特性

对 近 年 来 比 较 流 行 的 酸 奶 凝 胶 形 成 理 论 进 行 了 综 述 , 采如 用 动 态 低 振 幅 游 离 流 变 学 控 制 凝 胶 形 成 的 机 理 , 采 用 共 聚 焦 激 光 显 微 镜 来 测 定 凝 胶 的 微 结 构 , 许 多 阐 述 酸 诱 导 酸 奶 凝 胶 过 程 中 胶 粒 子 凝 聚 的 模 型 等 。     

κ-卡拉胶胶凝特性研究

以胶凝理论为基础,就卡拉胶质量分数、钾离子质量分数、ｐＨ值对胶凝特性的影响进行了定量分析与研究,并通过对实验数据的回归处理,总结出了κ－卡拉胶质量分数和钾离子质量分数与胶凝温度、凝胶强度之间的数学关系式,还探讨了ｐＨ值对κ－卡拉胶胶凝特性的影响．结果显示,随ｐＨ值降低,卡拉胶的凝胶强度快速下降．     

鸡骨明胶的胶凝特性

通过测定动态流变性质和凝胶强度研究鸡骨明胶的胶凝特性.研究表明,鸡骨明胶的胶凝分为凝胶网络的快速形成阶段和网络的缓慢成长两个阶段.相对分子质量越大,胶凝温度越低;明胶浓度越高、pH值越接近等电点、胶凝温度和熔化温度越高,胶凝时间越短,同时形成的凝胶网络的弹性和凝胶强度大;随着陈化时间的延长或温度降低,凝胶网络弹性和凝胶强度增大,且逐渐稳定;适当浓度的尿素和SDS可以阻止凝胶网络的形成;明胶胶凝网络结构的形成主要借助分子间氢键相互作用,同时静电斥力和疏水相互作用也影响凝胶网络的形成.     

理化指标对大米粉胶凝特性的影响

利用动态流变仪考察了8种不同理化指标的大米粉在加热和冷却过程中胶凝特性的变化,并用SPSS统计软件对大米粉理化指标和凝胶特征值进行了相关性分析。试验结果表明:对于米粉体系而言,直链淀粉含量、胶稠度和膨润力是影响其胶凝特性的主要因素, 3个因素的影响程度大小依次为直链淀粉含量、胶稠度、膨润力。米粉体系中蛋白质和脂类的含量等对米粉体系胶凝特性的影响不大,说明米粉体系的胶凝主要由米淀粉起着主导作用。     

亚麻籽胶的胶凝性质

采用流变学法测定了亚麻籽胶溶液的胶凝点、熔化点，并采用质构仪、扫描电镜和原子力显微镜等手段研究了影响亚麻籽胶凝胶强度的因素，结果表明亚麻籽胶具有胶凝性，它能形成一种热可逆的冷致凝胶，亚麻籽胶溶液的胶凝点低于其凝胶的熔化点，且亚麻籽胶溶液的胶凝点及其凝胶的熔化点均随冷却的起始温度的升高而升高。亚麻籽胶浓度、溶解温度、pH、NaCl、CaCl2及复合磷酸盐能影响亚麻籽胶的凝胶强度，亚麻籽胶的凝胶强度随着浓度的增加及溶解温度的升高而增强；在pH6～9的范围内，亚麻籽胶的凝胶强度达到最大；NaCl和复合磷酸盐可以降低亚麻籽胶的凝胶强度，低浓度（〈0．3％）的CaCl2可以增强亚麻籽胶的凝胶强度，而高质量分数（〉0．3％）的CaCl2能降低亚麻籽胶的凝胶强度。     

菜汁豆腐胶凝机理的探讨

本文对豆腐的胶凝机理、影响因素进行了理论探讨，以更好地理解菜汁豆腐胶凝基本原理，并对凝固作一概括介绍。     

The Role of Protein Denaturation,Extent of Proteolysis,and Storage Temperature on the Mechanism of Age Gelation in a Model System

A model system was used to investigate the effects of heat treatment, storage temperature, and proteolysis on the gelation time of both unconcentrated and concentrated (evaporated) milks. For unconcentrated milks, increasing levels of whey protein denaturation retarded the gelation process. Elevated storage temperatures accelerated the gelation process, but only in cases where milk samples had been previously proteolyzed. The actual extent of proteolysis was not related to gelation time. In evaporated milk, increasing temperature and extent of proteolysis reduced gelation time. Samples that had no induced proteolysis also gelled. Age gelation in unconcentrated and concentrated milks is controlled by two different mechanisms. In unconcentrated milk, gelation is a two-stage process where proteolysis is followed by nonenzymatic physicochemical changes. In concentrated milk, gelation occurrs by nonenzymatic physicochemical processes.     

Thermal Gelation in Relation to Binding of Bovine Serum Albumin-Polysaccharide Systems

Thermal gelation of bovine serum albumin (BSA)-sodium alginate, BSA-pectin and BSA-methyl cellulose systems in relation to binding was studied using rheological testing, turbidimetric analysis and gel filtration. Two electrostatic binding mechanisms, distinguished by particle and chain segment binding models were found in BSA-anionic polysaccharide systems. Particle binding resulted in poor gelation properties. Positive effects on gelation were found when conditions favored the chain segment binding model. Mechanisms for gelation-binding relationships were hypothesized. No evidence of binding was found in the BSA-methyl cellulose system, which generally exhibited the combined gelation properties of the individual components.     

Age Gelation,Sedimentation, and Creaming in UHT Milk: A Review

Demand for ultra‐high‐temperature (UHT) milk and milk protein‐based beverages is growing. UHT milk is microbiologically stable. However, on storage, a number of chemical and physical changes occur and these can reduce the quality of the milk. These changes can be sufficiently undesirable so as to limit acceptance or shelf life of the milk. The most severe changes in UHT milk during storage are age gelation, with an irreversible three‐dimensional protein network forming throughout, excessive sedimentation with a compact layer of protein‐enriched material forming rapidly at the bottom of the pack, and creaming with excessive fat accumulating at the top. For age gelation, it is known that at least two mechanisms can lead to gelation during storage. One mechanism involves proteolytic degradation of the proteins through heat‐stable indigenous or exogenous enzymes, destabilizing milk and ultimately forming a gel. The other mechanism is referred to as a physico‐chemical mechanism. Several factors are known to affect the physico‐chemical age gelation, such as milk/protein concentration, heat load during processing (direct compared with indirect UHT processes), and milk composition. Similar factors to age gelation are known to affect sedimentation. There are relatively few studies on the creaming of UHT milk during storage, suggesting that this defect is less common or less detrimental compared with gelation and sedimentation. This review focuses on the current state of knowledge of age gelation, sedimentation, and creaming of UHT milks during storage, providing a critical evaluation of the available literature and, based on this, mechanisms for age gelation and sedimentation are proposed.     

Influence of Cosolvent Systems on the Gelation Mechanism of Globular Protein: Thermodynamic,Kinetic, and Structural Aspects of Globular Protein Gelation

How thermostability and gelation of globular protein are affected by cosolvent systems present in food systems is critical to understanding their functionality. The expression of these functional attributes depends on the molecular structure and thermal‐mechanical history of the protein, as well as its chemical environment. To improve the design of processing protein‐containing food systems, one must fully understand the thermodynamic, kinetic, and structural impact of cosolvent on globular protein gelation. This review focuses on the impact of weakly interacting neutral cosolvent systems (for example, sugars and polyols) on the gelation of globular proteins. The physicochemical mechanisms by which these cosolvent systems can modulate protein gelation are highlighted from a thermodynamic, kinetic, and structural point of view.     

Technological strategies to improve gelation properties of legume proteins with the focus on lupin

There is a growing demand for plant protein due to the increasing number of consumers looking for healthier food options. Protein from the legume seed lupin is a viable plant protein source due its high protein content and agricultural sustainability of lupin production. Lupin protein is however underutilised in food manufacturing due to its poor gelling and thickening properties. This review uncovers the link between lupin protein structural properties and its poor gelling functionality. It will compare lupin with other legume proteins in terms of protein structure and gel quality. Current knowledge of legume protein gelation processes, factors controlling gelation mechanisms and methods for evaluating gel quality will be presented. Finally, green and efficient protein modification technologies to improve gelation will be detailed. This review also reveals the scarcity of information on approaches to improve the poor gelation properties of lupin protein, highlighting the need for research in this area.     

研究蛋白质凝聚凝胶的技术进展

由于蛋白质形成的凝胶会影响食品的质构和品质,所以研究蛋白质凝胶对于食品科学有极其重要的意义.然而,蛋白质形成凝胶的机理过于复杂,需要更先进的技术来研究.介绍了用于蛋白质凝胶研究的最新技术进展,如原子力显微镜(AFM),共聚焦激光显微镜(CSLM)和漫射波光谱(DWS).与传统研究凝胶的方法如动态流变仪和扫描电子显微镜(SEM)相比,这些新方法简化了样品的预处理,有实现在线测定的可能.由于样品处于天然状态,所以反映的信息更具有真实性,加上高分辨率,可以实现蛋白形成凝胶过程分子水平的可视化.因此,采用以上的新技术可以为研究蛋白凝胶的形成提供更多的信息.     

肌原纤维蛋白热诱导凝胶特性研究进展

肌原纤维蛋白质是肌肉中一类重要的结构蛋白质群,它对于肉食制品的品质和特性具有非常重要的影响.肌原纤维蛋白的凝胶特性是形成肉制品独特的质构、保水性、乳化性以及感官特性的决定性因素.本文介绍了肌原纤维蛋白凝胶机制、功能特性及其影响因素,为进一步了解肉制品加工特性提供一定理论指导.     

Gelation behaviour of aqueous solutions of different types of carrageenan investigated by low-intensity-ultrasound measurements and comparison to rheological measurements

The gelation of different carrageenans in aqueous solutions was investigated by ultrasound at 7.8 MHz and by oscillating rheological measurements. The gelation of κ-, κ/ι-hybrid-carrageenan as well as a mixture of κ- and ι-carrageenans causes an increase in ultrasonic attenuation and a decrease in ultrasonic velocity. However, the gelation of ι-carrageenan, which could be detected by the oscillating rheological measurement, did not cause detectable changes in the ultrasonic measurement. Different gelation behaviours of a κ/ι-hybrid-carrageenan and a mixture of κ- and ι-carrageenans were observed by both techniques. This illustrates that the analytical techniques studied, which are based on different principles, can differentiate the gelation behaviour of different carrageenan systems. This might have important implications on the elucidation of gel formation mechanisms which, for complex systems, cannot be explained using only one single analytical technique.     

魔芋胶-黄原胶复配体系流变学特性及其凝胶形成动力学分析

为探究魔芋胶与黄原胶2 种食品胶复配使用后的协同作用,以魔芋胶和黄原胶为原料,控制总凝胶质量分 数为1%,以魔芋胶与黄原胶质量比分别为2∶8、4∶6、5∶5、6∶4、8∶2进行复配后,考察复配体系的流变学特性并对 其凝胶形成进行动力学分析。结果表明：魔芋胶-黄原胶复配体系具有假塑性,当魔芋胶的添加比例逐渐增大时, 复配体系黏度系数K增大,流体系数n减小,且复配体系的动态黏弹性质也随着魔芋胶与黄原胶的质量比不同而改 变,当魔芋胶与黄原胶质量比为6∶4时,复配体系的K值达到最大、n值最小,具有最强的假塑性及黏弹性。同时, 魔芋胶与黄原胶的不同质量比对凝胶形成速率有较大影响,当质量比小于6∶4时,凝胶形成显示出较慢的速率,且 形成的凝胶强度较弱;当质量比为6∶4时凝胶形成速率加快,SDRa曲线和G’曲线上升明显,形成的凝胶强度增大, 当质量比继续增加时,凝胶形成速率反而降低。采用阿伦尼乌斯方程对凝胶形成过程中的动力学参数进行拟合,决 定系数均在0.98以上,表现出较高的拟合精度;凝胶形成过程中的活化能在魔芋胶与黄原胶质量比为6∶4时有显著 增加（P＜0.05）,高温段与低温段间的活化能也表现出明显差异。     

Covalent chemical modification of myofibrillar proteins to improve their gelation properties: A systematic review

To improve the quality of meat products is a constant focus for both the meat industry and scientists. As major components in meat protein, the gelation properties of myofibrillar proteins (MPs) predominantly determine the sensory quality and product yield of the final product. Naturally or artificially occurring covalent modifications are known to largely affect MP functionality by changing the protein structure and forming aggregates, leading to both favorable and unfavorable outcomes. The review aims to summarize the mechanisms associated with several covalent modifications and the recent developments in enhancing MP gelation properties. Various extrinsic and intrinsic parameters controlling oxidation, phenolic–protein interactions, enzyme catalysis, glycation, and isoelectric solubilization/precipitation, and their effects on the characteristics of heat-induced MP gels are discussed. This article provides an improved understanding of the covalent modifications that occur mainly in the MP system and how they can be utilized to promote its gelation properties. Covalent modifications exhibited dose-dependent and dual-role manners for MP gelation properties. Mild oxidation, enzyme catalysis, and isoelectric solubilization/precipitation treatment would be beneficial to form more aligned and cross-linked three-dimensional networks for MP gels because of moderate protein aggregation. However, an excessive aggregate impedes the MP gelation behavior, leading to reduced gelation quality. Glycation effectively increased hydrophilicity of MPs and phenolic conjugation provides MPs with novel bioactivity. A proper utilization of such a process or even a rational combination of them allowed us to enhance the gelation properties of MP with assorted appreciated functionalities and further improve the quality of meat products.