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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 the mathematical model of hygroscopicity of ginseng extract (GRRE) and analyze its hygroscopicity. Methods The gravimetric sorption / desorption isotherms of GRRE at 25, 35 and 45 ℃ were measured by gravimetric method. The isotherms were described by seven nonlinear regression equations. With the aid of 1st Opt statistical software, the root mean square error (RMSE ), Residual sum of squares (RSS) and coefficient of determination (R ~ 2) were used as evaluation indexes to select the best fitting model. The adsorption heats were calculated by the adsorption isotherms at 25, 35 and 45 ℃. Results At 25, 35 and 45 ℃, the adsorption and desorption isotherms of GRRE are better fitted by Peleg model, both belong to the second type. The desorption isotherm shows obvious hysteresis due to the high equilibrium water content, Hysteresis belongs to H_3 type. This hysteresis becomes weaker with increasing temperature. Adsorption heat increases with increasing equilibrium moisture absorption. Conclusion The Peleg model fit well to the sorption / desorption isotherms of GRRE, and the sorption / desorption isotherms have a hysteresis. The hysteresis phenomenon becomes weaker with increasing temperature, and the heat of adsorption is closely related to the equilibrium moisture content.