人参提取物吸湿特性及其数学模型

Moisture adsorption characteristics and mathematical models of Ginseng Radix et Rhizoma extract

目的拟合人参提取物(GRRE)吸湿过程数学模型并分析其吸湿特性。方法用称量法测试GRRE在25、35、45℃下吸附/解吸等温线,用7个非线性回归方程对等温线进行描述,借助1st Opt统计分析软件拟合,以均方根误差(RMSE)、残差平方和(RSS)和决定系数(R^2)为评价指标,筛选最佳拟合模型,结合25、35、45℃下吸附等温线计算吸附热。结果 25、35、45℃下,GRRE吸附/解吸等温线都是Peleg模型拟合效果较好,都属于第II种类型,解吸等温线因较高的平衡含水量而出现明显的滞后现象,该滞后现象属于H_3型。随着温度升高这种滞后现象变弱。吸附热随着平衡吸湿量的增大而增大。结论 Peleg模型较好地拟合GRRE的吸附/解吸等温线,且吸附/解吸等温线存在滞后现象,该滞后现象随温度升高而变弱,吸附热与平衡吸湿量密切相关。

Objective To fit mathematical model of moisture adsorption process and to analyze moisture adsorption characteristics for Ginseng Radix et Rhizoma extract（GRRE）. Methods Adsorption and desorption isotherms of GRRE were determined by gravimetric method at 25, 35, and 45 ℃, and seven models were used to fit experimental data by 1stOpt statistical analysis software package to ascertain the best of fit. Comparisons were evaluated with the coefficient of determination（R^2）, residual sum of squares（RSS）, and root mean square error（RMSE）. Adsorption heat was calculated by adsorption isotherm of 25, 35, and 45 ℃. Results Results indicated that adsorption and desorption isotherms belonged to type II behavior and the hysteresis loop was of type H_3. With the increase of temperature the hysteresis becomes weak and the heat of adsorption increases with the increase of equilibrium moisture content. The Peleg model was the best fitted for adsorption and desorption isotherms at 25, 35, and 45 ℃. Conclusion The Peleg model is suitable for fitting the adsorption and desorption isotherms and the isotherms exhibit an obvious hysteresis effect which becomes weak with the increase of temperature. The heat of adsorption is closely related to the equilibrium moisture content.