普鲁兰基多糖成膜溶液干燥动力学研究

Drying kinetics of pullulan-based film forming solutions

研究普鲁兰及普鲁兰—聚乙二醇可食用成膜溶液的干燥动力学。结果表明:所有样品在干燥过程中分为加速、降速和平衡3个阶段。纯普鲁兰样品干燥过程符合Wang and singh模型,普鲁兰—聚乙二醇复合膜液则符合Modified Henderson and pabis模型。当干燥温度由40℃升高到70℃,普鲁兰膜液的有效水分扩散系数从0.019 6×10^(-11) m/s^2增至0.255 7×10^(-11) m/s^2,而普鲁兰—聚乙二醇复合样品从2.400×10^(-11) m/s^2增至11.388×10^(-11) m/s^2。可见随着干燥温度的升高,膜液的有效水分扩散系数值也随之变大;并且在相同干燥温度下,普鲁兰膜液的有效水分扩散系数值比普鲁兰—聚乙二醇复合样品要低。通过Arrhenius类型方程计算得到普鲁兰膜液的干燥活化能为9 114.8kJ/mol,而普鲁兰—聚乙二醇复合膜液干燥活化能为2 475.2kJ/mol。

The drying kinetics of pullulan and pullulan-PEG film forming solutions were investigated.The results were as followed：the drying curves of pullulan-based films were divided into three stages：the rising rate,the falling rate,and the constant rate period;four mathematical models were fitted to the experimental data;among the drying models considered,the Wang and singh model was found to satisfactorily describe the drying kinetics of pullulan solutions.However,Modified Page equation-II model was found to satisfactorily describe the drying kinetics of pullulan-PEG solutions.As the drying temperature increased from 40 ℃ to 70 ℃,the effective moisture diffusion coefficient（Deff）of pullulan and pullulan-PEG samples increased from 0.019 6×10^（-11） m/s^2 to 0.255 7×10^（-11） m/s^2,and from 2.400×10^（-11） m/s^2 to 11.388×10^（-11） m/s^2,respectively.As the drying temperature increased,Deff of pullulan based film forming solutions increased,whereas the Deff of pure pullulan samples was lower than that of pullulan-PEG.Moreover,drying activation energy of pullulan and pullulan-PEG blend samples was9 114.8kJ/mol,and 2 475.2kJ/mol,respectively.