差示扫描量热仪及流变仪研究k-卡拉胶的凝胶特性

Study on the Gelling Properties of k-Carrageenan with DSC and Rheometer

应用旋转流变仪及差示扫描量热仪(DSC)研究了1.5%k-卡拉胶溶液(质量浓度)的水凝胶与钾凝胶的凝胶特性,分别从溶胶温度、凝胶温度、熔融焓、结晶焓及弹性模量等指标进行考察。结果表明:k-卡拉胶水凝胶的溶胶温度高于凝胶温度,钾凝胶的溶胶温度却低于凝胶温度;溶胶时弹性模量值明显高于凝胶时弹性模量。增加钾离子提高溶胶温度与溶胶时弹性模量,同时使凝胶温度增加,增加的幅度明显大于溶胶温度的增加幅度,而凝胶时弹性模量却低于水凝胶发生凝胶时的弹性模量。DSC结果表明水凝胶与钾凝胶溶胶温度均高于凝胶温度,水凝胶溶胶时热焓值低于凝胶时热焓值,而钾凝胶溶胶时热焓值高于凝胶时热焓值。钾凝胶相比于水凝胶,吸热熔化与结晶温度增加,熔融与结晶时热焓值亦相应出现增加。不同批次k-卡拉胶溶液的水凝胶与钾凝胶特性存在差异,特别是凝胶-溶胶转化时的弹性模量存在明显差异。水凝胶DSC曲线中吸热峰与放热峰的峰宽存在明显差异性,而钾凝胶发生熔融时峰宽均大于凝胶时结晶峰的峰宽。

In this paper the gelling properties of hydro-gel and potassium-gel of 1.5% k-Carrageenan solution（m/m） were studied separately, investigated from the gel-sol temperature, sol-gel temperature, melting enthalpy, enthalpy of crystallization and elastic modulus etc. The experimental results showed that the gel-sol temperature was higher than sol-gel temperature for the hydro-gel,while on the opposite for the potassium-gel,and the elastic modulus at gel-sol temperature was obviously higher than that at sol-gel temperature. Increasing the potassium could improve the gel-sol temperature and elastic modulus at the transition of gel-sol as well as the sol-gel temperature which was obviously improved higher than the increasing magnitude of the gel-sol temperature,while the elastic modulus of potassium-gel was lower than that of hydro-gel at sol-gel temperature. DSC results showed that the gel-sol temperature was higher than sol-gel temperature for hydro-gel and potassium-gel,while for hydro-gel the melting enthalpy was lower than enthalpy of crystallization and on the opposite for potassium-gel. Compared with hydro-gel,for potassium-gel the melting and crystallization temperature were increased as well as the increasing of enthalpy of melting and crystallization. There existed the difference of the gelling properties for the hydro-gel and potassium-gel produced from different batches of k-Carrageenan,especially for the elastic modulus at the gel-sol temperature. There existed the significant difference between the peak width of the melting and crystallization on the DSC curve for the hydro-gel and the peak width of melting was wider than that of the crystallization for the potassium-gel.