壳聚糖/明胶食品保鲜复合膜的热稳定性研究
Study on the thermal stability of chitosan/gelatin composite films for food preservation
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摘要: 采用溶液共混法制备壳聚糖/明胶复合膜,测定复合膜的透光率及水溶性,并用热重分析法系统研究了复合膜的热降解性能。结果表明,随着明胶含量的增加,复合膜的透光率上升,水溶性增强,热稳定性提高。热分析结果显示,复合膜在氮气中的热降解为两步反应,降解温度(T)随着明胶含量(X)的增加而升高,起始降解温度To=0.03467X+246.5,最大速率降解温度Tp=0.3460X+282.1,终止降解温度Tf=1.001X+311.9;对应于Tp的降解率Cp不受X的影响,平均值为35.32%±2.54%,对应于Tf的降解率Cf也不受X的影响,平均值为56.28%±1.56%;复合膜热降解反应的活化能(E)和频率因子(A)随反应程度的增加而改变,分三个过程。Abstract: Chitosan/gelatin composite films were prepared by solution blending, then the light transmittance, the water-solubility and the thermal degradation by thermogravimetry analysis of composite films were determined.Results showed that the light transmittance, the thermal stability and water-solubility of composite films rose with the increment of the content of gelatin. Thermal analysis results showed that the thermal degradation of composite films in the nitrogen was a two-steps reactions, and the degradation temperature (T) rose with the gelatin content (X) :the initial temperature of weight loss To=0.03467X+246.5, the temperature at the maximum weight loss rate Tp=0.3460X+282.1 and the final temperature at weight loss Tf=1.001X+311.9. Cp and Cf were the degradation rates which correspond to Tp and Tf separately, they were not affected by X, and the average value of Cp and Cf were 35.32%±2.54% and 56.28%±1.56%, respectively. The activation energy (E) and frequency factor (A) of the thermal degradation of composite films changed during the three reaction processes.