黄芪切片真空干燥特性与吸湿特性的研究

Study on vacuum drying characteristics and hygroscopic properties of Huangqi( A.mongholicus Bunge) slices

通过黄芪真空干燥实验,研究黄芪在不同干燥温度、真空度以及常压保持时间条件下的干燥特性,建立黄芪真空干燥过程的干燥模型;分析干燥后黄芪色泽度的变化,及不同干燥条件对黄芪粉吸湿特性的影响。实验结果表明,黄芪真空干燥过程分为两个阶段:恒速干燥阶段和降速干燥阶段(Mt<30%);干燥温度、真空度以及常压保持时间均对干燥过程有显著影响(p<0.05),温度越高、真空度越大、常压保持时间越短,所需干燥时间越短。线性模型和Weibull模型能够很好地分别表达出恒速干燥阶段和降速干燥阶段,决定系数R2的区间为0.9802~0.9997。色泽度和水活度分析显示,干燥后黄芪切片亮度明显高于干燥前,红绿值和蓝黄值较干燥前有所降低。随着干燥温度上升,亮度值有所下降;干燥后黄芪的水活度值均低于0.3。黄芪粉的吸湿特性实验表明,不同干燥条件对其吸湿特性的影响均无明显的变化趋势。研究结果为真空干燥技术在黄芪干燥中的应用提供理论支持。

The drying characteristics of Huangqi （A. mongholicus Bunge） was studied under the conditions of different drying temperatures,vacuum degrees, and atmosphere maintaining time, respectively by vacuum drying technology. The model of vacuum drying process of Huangqi was built. The change of color degree of Huangqi dried was analyzed and the effect of different drying conditions on the hygroscopic properties of Huangqi powder was discussed.The results showed that the vacuum drying process of Huangqi had two stages： the constant rate drying stage and the decreasing rate drying stage.The different drying conditions significantly affected the drying process. The higher temperature, the higher vacuum degree and the shorter atmosphere maintaining time caused the shorter drying time.The linear and Weibull composed model fitted the vacuum drying process of Huangqi well and the interval of the coefficient R~ was 0.9802~0.9997.The analysis of the colour showed that the lightness of Huangqi dried was brighter than before.But the red ＆ green value and blue ＆ yellow value were lower than before. The drying temperature had a significant effect on the brightness value and the brightness value decreased when the drying temperature increased.The dried Huangqi＇ s water activity was lower than 0.3. And there were no significant changes in the hygroscopic properties of Huangqi powder under different drying conditions. The results provides theoretical support to the vacuum drying process of the Huangqi.