香葱叶片微波-热风联合干燥工艺优化及干燥动力学研究

Optimization of Microwave Combined Hot-Air Drying Process and Drying Dynamics Model of Chive Leaf

以香葱叶片为对象,研究微波-热风联合干燥香葱叶片的最佳工艺条件。采用单因素试验考查微波功率、转换点含水率和热风温度对香葱叶片干燥速率、复水比、ΔE值、硫代亚磺酸酯和蒜氨酸保留率的影响,利用响应面试验优化微波联合热风干燥香葱叶片的工艺条件,同时对微波联合热风干燥香葱叶片的干燥动力学进行研究。微波功率、转换点含水率和热风温度对脱水香葱叶片品质有显著影响,最优工艺参数为微波功率3000 W,转换点含水率40%,热风温度75℃。联合干燥前期微波干燥动力学模型为Page模型,回归方程为MR=exp(0.03126t1.79815),后期热风干燥为Midilli模型,回归方程为MR=0.30427exp(0.13891t)0.000175419t,R2分别为0.998和0.999。表明2个模型能够良好预测香葱叶片微波联合热风连续干燥过程,可为生产中香葱叶片干燥提供理论和技术支撑。

The aim of this study was to find the optimum processing conditions for the microwave combined hot air drying chive leaf.Firstly,the one-factor-at-a-time method was used to examine the effects of microwave power,conversion point moisture content and hot air temperature on the drying rate,rehydration ratio,ΔE value,thiosulfinate and alliin retention rate of drying chive leaf.Subsequently,response surface methodology was used optimize the microwave power,conversion point moisture content and hot air temperature,and established its drying kinetics model.Results showed that all the above four factors had influences on the quality of dried chive leaf,and optimal result of microwave combined with hot air drying of leaf were microwave power 3000 W,moisture content at conversion point 40%,hot air temperature 75℃.The kinetics model of microwave drying was Page:MR=exp(0.03126t1.79815)and hot air drying was Midili:MR=0.30427exp(0.13891t)0.000175419t,R2 was 0.998 and 0.999,respectively,which showed that the two models could predict the continuous drying process of chive leaf in microwave combined with hot air.These experimental results could provide theoretical and technical support for industrial production of dried chive leaves.