食用/工业明胶的凝胶及LF-NMR弛豫特性的比较

Comparison of Gel and LF-NMR Relaxation Properties of Edible/Industrial Gelatin

该文研究了食品/工业明胶浓度、混合比例及蔗糖或NaCl对体系的黏度、凝冻强度及LF-NMR弛豫特性的影响。结果发现,与食用明胶相比,工业明胶的凝冻强度与黏度较低。随着明胶浓度的增加,体系的黏度、凝胶强度均相对增大;结合水弛豫时间T_(21)、自由水弛豫时间T_(22)及自由水比例S_(22)均减小,而结合水比例S_(21)增大。随着工业明胶含量的增多,混合体系的黏度与凝冻强度均线性降低,T_(21)、T_(22)及S_(21)均线性增大,S_(22)线性减小;相同蔗糖或NaCl浓度下,食用明胶体系的黏度、凝冻强度最大,混合明胶体系次之,而工业明胶体系的最小;随着蔗糖浓度的增加,体系的黏度均增大,食用、混合体系的凝冻强度增大,而工业明胶变化较小;各体系的T_(22)、S_(22)均减小,S_(21)增大,工业明胶的T_(21)增大,而食用明胶、混合明胶体系的T_(21)变化不大。随着NaCl浓度的增加,各体系的凝冻强度均相对降低,而T_(21)、T_(22)、S_(21)均相对增大,S_(22)减小。

The effects of edible/industrial gelatin concentrations,mixing ratio and sucrose or sodium chloride(NaCl)solutions on viscosity,gel strength and low-field nuclear magnetic resonance(LF-NMR)relaxation properties of the gelatin gel system were studied in this paper.The results indicated that the industrial gelatin had much lower viscosity and gel strength than edible gelatin.With the increase of gelatin concentration,the viscosity and gel strength of the gelatin system increased relatively.The relaxation time for bound water(T 21)and free water(T 22)were reduced,and the proportion for free water(S 22)decreased while that for bound water(S 21)increased.As the content of industrial gelatin increased,the viscosity and gel strength of mixed gelatin system decreased linearly,and T 21,T 22 and S 21 increased,while S 22 decreased linearly.In the same sucrose or NaCl concentration,the edible gelatin system had largest viscosity and gel strength,mixed gelatin system took second place,while the industrial gelatin system had lowest viscosity and gel strength.With the increase of sucrose concentration,the viscosity of each system increased,the gel strength of edible and mixed system increased,while those of industrial gelatin changed slightly.Besides,the T 21 for industrial gelatin increased,while that for edible/mixed gelatin system changed insignificantly.The T 22,S 22 for three systems reduced,while the S 21 increased.The gel strength of each gelatin system decreased with the increase of NaCl.The T 21,T 22 and S 21 for each system all increased,while S 22 decreased.