加热诱导海参体壁易变胶原组织水分吸附及“锁水”机制的研究

Water soaking is the traditional method to prepare dried sea cucumber, which is still widely used today. Our previous studies have shown that the mutable collagenous tissue (MCT) in Sea cucumber body wall can form special spongiform structure through a high temperature cooking- low temperature water-soaking process. The spongiform structure significantly affects the textural quality of the processed sea cucumber. However, it is still unclear how the MCT turns into these spongiform structures, neither is it clear how these structures absorb and bind to water that alters the sea cucumber sensory properties. In this study, we aim to utilize SEM, X-ray and HPLC-MS etc. to investigate the formation of the spongiform structure in sea cucumber MCT at molecular and microscopic levels, and to understand its mechanism. By using LF-NMR and fractional analysis, we aim to develop a novel water absorption model for sea cucumber MCT based on BET multilayer absorption theory to characterize the change of its water binding properties, and to explore the mechanism of the swelling of the insoluble MCT backbone and the formation of hydrogel within the MCT structure during water soaking. Furthermore, in situ Raman spectroscopy will be applied to analyze the water-binding sites inside the MCT structure, in combination with GROMACS program and molecular dynamics simulation a predictive model is to be developed to reveal the water binding capacities of the MCT structure. Our ultimate goal in this study is to understand the microstructural and molecular mechanism of water-MCT interaction, and to provide theoretical and scientific foundation for sea cucumber processing.

水发海参这种加工方式，因其重要的应用价值传承至今。前期研究发现，海参体壁易变胶原组织（MCT）经高温煮制-低温水发形成特殊“海绵状结构”，决定了产品质构。然而，该结构的吸水和“锁水”机制尚未明确。针对上述问题，本项目运用电镜、X射线衍射、HPLC-MS等手段从微观和分子层面探究海参MCT“海绵状结构”形成机理；基于BET多层吸附理论，借助低场核磁技术和图像分形维数计算技术，构建海参MCT水分吸附动力学模型；通过模拟水发条件，研究海参MCT纤维骨架的溶胀规律，可溶物凝胶的化学作用力变化规律，探究水凝胶体系的水分状态和凝胶性质；采用原位激光拉曼光谱结合核磁共振氢谱、碳谱分析水合作用靶位点，结合分子动力学模拟与GROMACS程序预测水合胶原蛋白的分子结构。本研究从微观和分子水平构建了海参水发的结构基础，阐明吸水和“锁水”机制，为海参研究和加工奠定理论基础。

海参水发加工和食用方式，因其重要的应用价值传承至今。海参体壁易变胶原组织（MCT）经高温煮制-低温水发形成特殊“海绵状结构”，决定了产品质构。项目围绕海参体壁易变胶原组织结构变化以及胶原和非胶原组分变化开展研究，揭示其吸水和“锁水”机制。.1.采用光学显微镜、扫描电镜、透射电镜等一系列手段，观察高温蒸煮过程中海参体壁MCT微观结构变化。煮制过程中海参体壁MCT结构小束纤维先收缩聚集成大束的纤维，后失去规则性后开始降解；海参体壁蒸煮时长超过一定时间后其MCT胶原纤维完全变性，结构呈现为明胶的网状结构。.2.利用SDS-PAGE结合化学实验，分析高温蒸煮过程中胶原和非胶原组分的变化以及热变性规律。随热处理时间延长，羟脯氨酸和糖胺聚糖的总溶出量逐渐增加，印证MCT结构中纤维结构和桥连结构发生了进一步断裂降解；海参纵肌肌球蛋白在较低加热温度便发生热变性，重酶解肌球蛋白数量、Ca2+-ATPase活性和剩余的肌动蛋白含量逐渐减少，表明各组分共同影响海参体壁组织结构。.3.借助低场核磁共振技术、磁共振成像技术以及流变分析，明确MCT结构中水分变化规律。随煮制时间延长，海参组织对水分的束缚能力逐渐降低，水分流动性增大；以纤维结构为主的海参胶原组织进一步降解，表现为海参体壁表观粘度逐渐降低；I850/I830值逐渐增加，蛋白酪氨酸苯环上羟基暴露，与水环境中水分子作用增强，蛋白-水分子氢键逐渐增多，蛋白-蛋白氢键逐渐减少。.4.基于蛋白组学技术，分析胶原、非胶原蛋白组分的差异蛋白变化，证实热处理过程中，含胶原蛋白的细胞外基质相关差异蛋白先显著富集，后MCT结构遭到破坏，片段化的胶原链增多，基质溶出，且微纤维结构破坏早于胶原纤维。.本研究从微观和分子水平观察海参MCT组织的微观结构及组分变化，阐明吸水和“锁水”行为机制，为海参研究和加工提供理论基础，对推进传统技术升级和产品创新有重要意义。