摘要
为探索山药微波热风耦合干燥特性,采用微波热风耦合干燥技术研究不同切片厚度、热风温度、热风速率和微波功率密度对山药干燥特性及水分有效扩散系数的影响,并建立干燥动力学模型。结果表明:山药微波热风耦合干燥过程按干基含水率的变化主要分为加速和降速两个阶段,无明显恒速阶段;山药的水分有效扩散系数范围为0.879 1×10^(-6)～8.245 8×10^(-6) m^2/s,其值与切片厚度、热风温度和微波功率密度成正比,并随热风速率的增大先减小后增大;与热风速率和热风温度相比,切片厚度和微波功率密度对水分有效扩散系数的影响更加显著。通过拟合9种常用干燥模型,表明Two-term exponential模型的R^2平均值最大,χ~2平均值和均方根误差平均值最小,分别为0.998 0、0.000 2和0.014 7。相同实验条件下Two-term exponential模型的预测值与实验值拟合较好,表明该模型适合预测山药微波热风耦合干燥过程的水分含量变化规律。本研究结果可为微波热风耦合干燥技术应用于山药及其他农产品的干燥提供理论依据。
The effects of material thickness,air temperature,air velocity and microwave power on the drying characteristics and effective moisture diffusion coefficient were investigated by using microwave coupled with hot air.Meanwhile,a model for describing the drying kinetics was established through nonlinear fitting.The experimental results showed that the drying process was mainly divided into two periods,namely accelerated and decelerated change of dry basis moisture content,without obvious constant-speed period.The effective moisture diffusion coefficients,ranging from 0.879 1×10-6 to 8.245 8×10-6 m 2/s,were directly proportional to material thickness,air temperature and microwave power density and initially decreased and then increased with increasing air velocity.Furthermore,the effects of material thickness and microwave power density on effective moisture diffusion coefficient were greater than those of air temperature and air velocity.Among 9 common drying kinetic models,the mean values of R2,χ2 and root-mean-square error for the Two-term exponential model were minimum,which were 0.998 0,0.000 2 and 0.014 7,respectively.The predicted values from this model were nearly consistent with the experimental values under identical experimental conditions.Therefore,the model could be used to predict the moisture change of Chinese yam during the drying process.These research findings can provide a technical foundation for the application of microwave coupled with hot air in the drying of Chinese yam and other agricultural products.
作者
王汉羊
刘丹
于海明
WANG Hanyang;LIU Dan;YU Haiming(College of Engineering,Heilongjiang Bayi Agricultural University,Daqing 163319,China)
出处
《食品科学》
EI
CAS
CSCD
北大核心
2018年第15期115-121,共7页
Food Science
基金
"十二五"国家科技支撑计划项目(2014BAD06B01)
黑龙江省自然科学基金项目(C2015037)
关键词
山药
微波热风耦合
干燥特性
Chinese yam
microwave coupled with hot air
drying characteristics
