青葱微波真空干燥特性及动力学模型

采用微波真空干燥技术对青葱进行干制加工,研究了微波功率、装载量、真空度、物料层厚度等因素对青葱失水特性的影响,建立了青葱含水率随干燥时间变化的动力学模型.结果表明:青葱微波真空干燥过程具有升速、恒速和降速3个干燥阶段,其干燥速率随微波功率的增大、装载量的减少、真空度的增大而升高,且最佳物料层厚度为50 mm;青葱微波真空干燥过程符合Page模型,利用该模型可准确预测干燥过程中物料含水率及失水速率的变化情况.

Microwave vacuum drying characteristics and kinetics model of scallion

Microwave-vacuum drying(MVD) was used to dry scallion.The effects of microwave power,loadage,vacuum degree and thickness on the dehydration rate of scallion were studied.The suitable kinetics model which could be used to describe the relationship between moisture ration and drying time was established.The results showed the MVD process of scallion was divided into three stages such as speed-up,constant-speed and speed-down phase.The dehydration rate was quicker when the microwave power and vacuum degree were higher and the loadage was lower.The drying time was the shortest when the thickness of scallion was 50 mm.The drying process of scallion could be accurately described by Page model.The moisture contents and dehydrating rate during drying procedure also could be exactly estimated by the model.