金银花红外鼓风干燥特性、失水动力学及干制品品质研究
Drying characteristics,drying kinetics and product quality of Flos lonicerae during infrared-forced air drying
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摘要: 目的:研究金银花的红外鼓风干燥特性及其动力学模型。方法:金银花在不同温度(35、45、55℃)条件下进行红外鼓风干燥,计算水分比、干燥速率等参数,拟合建立干燥动力学数学模型,并测定干制品的色泽、主要成分等干燥特性。结果:金银花在红外鼓风干燥过程中,干燥温度越高,用时越短,降速阶段为其干燥的主要阶段。干燥的动力学模型拟合结果表明Page模型的预测值与实验值吻合性好,可以用来预测和描述金银花红外鼓风干燥的失水过程。费克第二定律求得干燥过程中的水分有效扩散系数(Deff)在5.06606×10-97.59909×10-8m2/s内,且随温度的升高而增大;阿伦尼乌斯方程计算得出金银花红外鼓风干燥平均活化能为113.569 k J/mol。35℃时金银花的色差值ΔE最小,有效成分含量最高,与阴干相比可提高效率并保证产品质量。结论:金银花红外鼓风干燥的主要阶段为降速阶段,Page模型适于预测和描述其失水过程,35℃红外干燥与阴干相比可提高效率,且产品品质更优。Abstract: Objective: To study the infrared- forced air drying characteristics and drying kinetics mathematical model of Flos lonicerae.Methods: The experiment was carried out at different infrared radiation drying temperatures( 35,45,55 ℃).The drying characteristics were detected and the drying kinetics mathematical model was established.Meanwhile,the value of colour and effective constituents were detected. Results: The drying time decreased with the increase of the drying temperature.According to statistical parameters,the Page model predicts and describes the drying process more accurately than others. There was a good agreement between the experimental and predicted values.Since the drying process occurred in falling rate periods,the Fick's second law of diffusion was employed to calculate the value of moisture effective diffusivity( Deff),which ranged from 5.06606 × 10- 9~7.59909 ×10- 8m2/ s,and increased with the increasing of drying temperature. The value of ΔE was least and the effective constituent was maximum at 35 ℃ of Flos lonicerae.The activation energy determined from Arrhenius equation was113.569 k J / mol. Conclusion: The drying process of Flos lonicerae only contained deceleration stage.The Page model was the best suitable for predicting moisture ratio.The infrared drying at 35 ℃ compared with drying in the shade was more efficient.