基于明胶/六偏磷酸钠/谷氨酰胺转氨酶复合水凝胶包埋体系的构建及作用机理

Construction and Mechanism of Action of Gelatin/Sodium Hexametaphosphate/Glutamine Aminotransferase Based Composite Hydrogel System

研究以明胶(gelatin,GE)和六偏磷酸钠(sodium hexametaphosphate,SHMP)为原料,制得初级网络水凝胶,添加植物乳杆菌后采用谷氨酰胺转氨酶(transglutaminase,TGase)进一步交联构建复合水凝胶包埋体系,以期提高植物乳杆菌的存活率和生物利用度。结果表明,经SHMP和TGase修饰后改变了GE的凝胶强度、水分分布状态及凝胶网络结构,同时降低了凝胶形成速率,使凝胶的三维网络结构更加稳定,GE/SHMP/TGase复合水凝胶包埋体的分子间作用力较强,有利于包埋的植物乳杆菌的抵抗不良环境的影响。通过扫描电子显微镜发现植物乳杆菌的存在轻微破坏了水凝胶的有序结构。内源荧光光谱分析表明植物乳杆菌的加入导致GE分子内含有的色氨酸的延伸区暴露在更极性的环境中,在水凝胶胶凝过程中出现空间位阻效应,延缓了生物聚合物分子间共价交联和物理相互作用的形成,从而导致其微观结构发生改变。模拟胃肠道消化实验及贮藏实验表明,与单一的GE基水凝胶相比,GE/SHMP/TGase凝胶中植物乳杆菌具有更高的益生菌细胞存活率及胃肠道释放特性。证实了GE/SHMP/TGase复合水凝胶对植物乳杆菌具有较好的保护作用。本研究探索了一种制备益生菌递送系统的新方法,为益生菌功能性食品的开发提供理论依据。

In this study,a composite hydrogel system was constructed by cross-linking of primary network hydrogels of gelatin(GE)and sodium hexametaphosphate(SHMP)by transglutaminase(TGase)after addition of Lactobacillus plantarum in order to improve its viability and bioavailability.The experimental results showed that the modification by SHMP and TGase changed the gel strength,water distribution state,and gel network structure of gelatin,and reduced the gelation rate,so that the three-dimensional network structure of the gel was more stable,and the intermolecular forces of the composite hydrogel was stronger,contributing to the resistance of the encapsulated L.plantarum to adverse environments.The presence of L.plantarum was found to slightly disrupt the ordered structure of the hydrogel by scanning electron microscopy(SEM).Endogenous fluorescence spectroscopy analysis showed that addition of L.plantarum resulted in the exposure of the extended region containing tryptophan within the GE molecule to a more polar environment.The steric effect occurred during the gelling process,delaying the formation of covalent crosslinks and physical interactions between the biopolymer molecules,which led to changes in their microstructure.Simulated gastrointestinal digestion tests and storage tests showed that L.plantarum encapsulated in GE/SHMP/TGase gels had better survival rates and gastrointestinal release properties compared to single GE-based hydrogels.It was confirmed that GE/SHMP/TGase hydrogels had a better protective effect on L.plantarum.In conclusion,this study has explored a new method for preparing GE-based hydrogels as a delivery system for probiotics,which will provide a theoretical basis for the development of probiotic functional foods.