超声波处理改善类PSE鸡肉肌球蛋白热诱导凝胶特性的机制研究

Pale, soft, and exudative (PSE)-like chicken meat quality defect resulted in meat having light color, low water-holding capacity, impaired functional properties and its occurrence was higher than 20% in the poultry industry. However, mechanisms of inferior functional properties of PSE-like chicken breast meat and modifying its functional properties are not well-understood. Therefore, the objective of this study is to investigate denaturation and thermal gelling properties of PSE-like chicken meat myosin, the effect of ultrasound-induced structural changes of PSE-like chicken meat myosin on heat induced gelation. Gel strength, water-holding capacity, solubility, dynamic rheological properties, protein thermal stability, changes in fractions of myosin cleaved by chymotrypsin as well as molecular forces were measured. During heat-induced gelation, thermal aggregation of myosin were analyzed by dynamic light scattering experiments, protein conformational changes were measured using Raman spectroscopy and circular dichroism, the microstructure of myosin were also probed by transmission electron microscopy and atomic force microscopy. These results will contribute to clarifying the relationships between myosin structural changes and inferior gel properties, and the mechanisms of heat-induced gelation of PSE-like chicken breast meat myosin improved by ultrasound treatment, thus providing theoretic evidence in modifying the functional properties of PSE-like chicken meat and developing gel-type meat products processing.

类PSE鸡肉颜色苍白，保水性差，加工品质低，在肉鸡屠宰工业中发生率高于20%。然而，类PSE鸡肉蛋白质凝胶特性劣变及改善的分子机制尚未阐明。因此，本项目系统研究类PSE鸡肉肌球蛋白的变性状态和热诱导凝胶形成特征，以及基于超声波诱导的肌球蛋白结构修饰对类PSE鸡肉蛋白质热诱导凝胶特性的影响；检测类PSE鸡肉肌球蛋白的凝胶强度、保水性、溶解性、动态流变学特性、热稳定性、组成成分以及凝胶形成中分子间作用力；借助动态光散射技术分析肌球蛋白热诱导凝胶形成中的聚集状态变化，应用拉曼光谱和圆二色光谱分析肌球蛋白的构象变化，应用透射电镜和原子力显微镜观察肌球蛋白热诱导凝胶形成中的微观结构变化，以期揭示类PSE鸡肉肌球蛋白的结构与热诱导凝胶特性劣变关系，阐明超声波处理改善类PSE鸡肉肌球蛋白凝胶特性的机制，为改善类PSE鸡肉的加工品质和研发凝胶类肉制品提供理论参考。

本项目研究了类PSE鸡肉蛋白凝胶特性劣变机制以及基于超声波诱导的鸡肉蛋白质修饰对其蛋白功能特性的影响。研究表明，类PSE鸡肉蛋白与正常鸡肉蛋白的组成成分相似，然而，类PSE鸡肉蛋白凝胶特性变差主要原因是本身蛋白粒径变小、肌肉蛋白热稳定性变差，加热时更容易发生聚集。通过探索各种超声波参数以及处理蛋白浓度，发现短时间低频高强度超声波（20 kHz，30 W/cm2， 6 min）显著增加了蛋白溶解度和ζ电位绝对值，降低了蛋白浊度和黏度；SDS-PAGE电泳显示，超声波处理对蛋白质条带没有影响；而经过超声波处理后，表面疏水性及活性巯基含量显著上升；内源性荧光强度增强，揭示了蛋白质的三级结构发生变化，增加了蛋白分子的伸展性；圆二光谱和傅里叶红外光谱显示蛋白的有序α-螺旋含量显著降低，松散的β-折叠、β-转角和无规则蜷曲含量显著上升；原子力显微镜表明蛋白结构被破坏，形貌特征表现为较小粒径的分散颗粒，表面粗糙度显著降低。低频高强度超声波处理降低了蛋白自组装程度，使结构变得更加无序，促进聚集体破碎，并形成小的可溶性蛋白聚集物，同时静电相互作用增强；动态流变学显示了超声波处理明显增加蛋白的弹性模量和粘性模量，加热过程中促进了肌球蛋白解折叠展开程度，增加分子间交联程度，增强其热诱导凝胶形成能力，对类PSE肌球蛋白凝胶特性具有潜在改善作用。本课题研究了类PSE鸡肉蛋白凝胶特性劣变机制以及超声波对鸡肉蛋白的作用机制，为改善类PSE鸡肉的加工品质和超声波技术在凝胶肉品加工中的应用提供理论基础。