白萝卜间歇微波热风耦合干燥过程干燥特性分析

对比不同的间歇微波功率与热风耦合干燥及间歇微波干燥对白萝卜干燥特性（水分比、有效扩散系数和活化能）、中心与表面温度和颜色的影响。结果表明，有效扩散系数随水分含量的下降先缓慢上升后快速上升，活化能随水分含量的降低先缓慢升高后快速升高，Logistic模型能很好地反映活化能和水分之间的关系，并且单独进行间歇微波干燥的样品的活化能较高。干燥条件设定为间歇比5 s/20 s，热风温度30 ℃的样品其在干燥过程中物料中心温度最低，中心温度与物料表面温度相差最少，且干燥产品颜色最好。

Drying Characteristics of Intermittent Microwave Coupled with Air Drying of Chinese Radish (Raphanus sativus L.) Slices

The effectiveness of various microwave-convective drying treatments (pulse ratio and air) on the drying characteristics and quality of white radish slices was studied. The moisture ratio, drying rate, effective diffusivity (Deff), and activation energy (Ea) were assessed, and the internal temperature of samples during the drying process and final product color were measured. The Deff increased gradually and then rapidly as moisture content decreased. The Ea of samples increased slightly and then increased rapidly as the moisture content decreased. A logistic model could describe the relationship between Ea and moisture content well. The Ea of samples without air was the highest. Among all the drying treatments, the samples dried with a high pulse ratio (on/off, 5 s/20 s) at a low hot air temperature (30 ℃) exhibited the lowest temperature and the lowest difference between the maximum and minimum temperature of samples and had the most desirable color.