κ-卡拉胶比例对明胶凝胶体系凝胶特性、水分分布及微观结构的影响

Effects of κ-carrageenan ratio on gel properties,water distribution,and microstructure of a gelatin-gel system

论文采用质地剖面(texture profile analysis,TPA)/穿刺分析、低场核磁场共振(low-field nuclear magnetic resonance,LF-NMR)、计算机断层扫描技术(computed tomography,CT)和流变仪研究了κ-卡拉胶的比例对明胶凝胶的凝胶强度、质构特性、水分分布、动态黏弹性和微观结构的影响,并分析了几者之间的相关性。结果表明:随κ-卡拉胶比例的增加,混合凝胶体系的凝胶强度、硬度、咀嚼性、胶凝温度及熔化温度相对增大,弹性及内聚性降低,黏性和回复性先下降后上升;凝胶网络结构趋向于致密、均匀;结合水比例(S_(21))下降,不易流动水比例(S_(22))相对增加,且当体系中κ-卡拉胶的比例逐渐增加至50%时,单组份弛豫时间(T_(2W))及不易流动水的弛豫时间(T_(22))的减小较为明显,而结合水的弛豫时间(T21)变化相对较小;相关性分析表明,凝胶强度、硬度、咀嚼性与S_(21)负相关,与S_(22)、T21正相关。弹性与S_(21)、T_(22)和T_(2W)正相关,与S_(22)负相关。内聚性与T_(22)和T_(2W)正相关。研究可为明胶-κ-卡拉胶复配胶在食品中的应用提供理论支持。

The effects of κ-carrageenan ratio on gel strength, texture characteristics, water distribution, dynamic viscoelasticity, and microstructure of a gelatin-gel system were studied. Besides, the correlations among these properties were analyzed. The results showed that with increasing κ-carrageenan ratio, the gel strength, hardness, chewiness, gelation temperature, and melting temperature of the system all enhanced, while its springiness and cohesiveness decreased gradually. Moreover, its adhesiveness and resilience increased after an initial decrease. Additionally, the network structure of the system was more uniform and compact. Furthermore, the proportion of bound water in the system (S21) gradually decreased, while that of immobile water (S22) increased relatively. As the κ-carrageenan ratio increased to 50%, significant reductions in single-component relaxation time (T2W) and that of immobile water (T22) were found, but changes in bound water relaxation time(T21) were relatively small. Correlation analysis showed that gel strength, hardness, and chewiness of the system were negatively correlated with S21 but positively correlated with S22 and T21. In addition, springiness was positively correlated with S21 , T22 , and T 2W but negatively correlated with S22 . Cohesiveness was positively correlated with T22 and T2W . Overall, this study provides theoretical supports for applying compounded gels with gelatin and κ-carrageenan in foods.