基于应力松弛原理的高酰基结冷胶凝胶特性研究

Gelling Properties of High-acyl Gellan Gum Based on the Stress Relaxation Theorem

摘要:

本文采用应力松弛模式研究了一价离子（K+和Na+）和二价离子（Ca2+和Mg2+）对高酰基结冷胶凝胶特性的影响。结果表明：高酰基结冷胶凝胶的应力松弛行为符合Peleg经验模型。离子浓度和离子种类对高酰基结冷胶凝胶应力松弛行为影响显著，平衡弹性模量（EA）随着离子浓度的增加呈马鞍形趋势变化，且其与凝胶硬度呈现较好的正相关（R=0.943~0.983），表明EA可以用来表征高酰基结冷胶凝胶的强度。相对于一价离子(K+、Na+)而言，二价离子(Ca2+、Mg2+)形成的凝胶强度更高，且用量更少。在相同离子浓度下，Na+形成的凝胶比K+形成的凝胶强，Ca2+形成的凝胶则比Mg2+形成的凝胶强。在16000 g下离心10 min，高酰基结冷胶凝胶保水性均在95%以上，与离子浓度基本无关，保水性能优异。高酰基结冷胶应力松弛机制是体系内部物理交联点的移动。

Abstract:

In this study, the stress-relaxation model was used to examine the effects of monovalent (K+ and Na+) and divalent (Ca2+ and Mg2+) cations on the gelling properties of high-acyl gellan gels. The results suggested that the stress relaxation behavior of high-acyl gellan gels fitted well with Peleg’s empirical model. The types and concentrations of cation had significant effects on the stress relaxation behavior of high-acyl gellan gels. The values of equilibrium modulus (EA) formed a saddle-shape curve with increasing cation concentration and correlated positively with gel hardness (R = 0.943 to 0.983), indicating that EA could be used to characterize gel strength. The gels formed by divalent cations showed greater gel strength than those formed by monovalent cations. At constant concentrations of cation, gellan gels formed by Na+ were stronger than those formed by K+, whereas gels formed by Ca2+ were stronger than those formed by Mg2+. When subjected to 16,000 ×g centrifugal force for 10 min, all high-acyl gellan gels exhibited water-holding capacity of more than 95%. In addition, the water-holding capacity of high-acyl gellan gels was less sensitive to changes in K+, Na+, Ca2+, and Mg2+ concentrations. The mechanism of stress relaxation appeared to be associated with the movement of physical cross-links in the gel matrix.