论文主要研究了不同浓度的蔗糖及NaCl对明胶凝胶体系低场核磁共振（LF-NMR）弛豫特性的影响，并应用主成分分析（PCA）对弛豫特性及其与明胶凝冻强度的相关性进行了分析。结果表明，随蔗糖浓度的增加，明胶-蔗糖凝胶体系的结合水弛豫时间（T21）延长，自由水弛豫时间（T22）和单组份弛豫时间（T2w）缩短，结合水比例（S21%）增大，而自由水比例（S22%）相对减少；而随NaCl浓度的增加，明胶-NaCl凝胶体系的T21、T22和T2w均相对延长，S21%和S22%则分别增大和减少。两种凝胶体系之间及其与相应的溶剂之间在PCA得分图上均有明显的区分，且明胶-蔗糖/NaCl凝胶体系的凝冻强度与其LF-NMR主成分综合得分间存在良好的相关性。研究表明，LF-NMR技术可以有效反映明胶-蔗糖/NaCl凝胶体系中水分状态及其相应比例的变化，且可反映其凝冻强度的变化，这可为明胶应用于食品生产加工提供一定的指导作用。

The effects of sucrose and sodium chloride (NaCl) solutions at different concentrations on the low-field nuclear magnetic resonance (LF-NMR) relaxation properties of gelatin gel system were studied. Principal component analysis (PCA) was used to analyze the correlation of relaxation properties of gelatin gel system with gel strength. The results for the gelatin-sucrose gel system indicate that the relaxation time of bound water (T21) was prolonged, while that of free water (T22) was reduced, with increasing concentration of sucrose. Additionally, mono-component relaxation time (T2w) was shortened, while proportions of bound water (S21%) and free water (S22%) were increased and reduced, respectively. The results for gelatin-NaCl gel system show that with increase in NaCl concentration, the T21, T22, and T2w were relatively prolonged, while S21% and S22% were similarly increased and reduced, respectively. The two gel systems and their corresponding solvents could be distinctly distinguished from each other on the principal component (PC) score plot, and the gel strength of gelatin-sucrose/NaCl gel systems showed good correlation with the LF-NMR-PCA comprehensive score. The results of this study indicate that LF-NMR technique effectively reflects changes in the state of water and its corresponding proportion in gelatin-sucrose/NaCl gel systems, while also reflecting changes in gel strength. This may have applications in gelatin-based food production and processing. Key words: gelatin; low-field nuclear magnetic resonance; principal component analysis; sucrose; sodium chloride

国家自然科学基金（NSFC31201365）；上海市科委重点攻关项目（11142200403）；上海市教委科研创新项目（11YZ109）