白萝卜薄层热风干燥特性及其数学模型  

Drying characteristics and mathematical model on hot-air drying of chinese radish slices

作　　者：黄珊 王修俊 沈畅萱[1,3] 

机构地区：[1]贵州大学酿酒与食品工程学院,贵州贵阳550025 [2]贵州省农业科学院生物技术研究所,贵州贵阳550006 [3]贵州大学发酵工程与生物制药省级重点实验室,贵州贵阳550025

出　　处：《食品与机械》2017年第8期137-143,193,共8页Food and Machinery

基　　金：贵州省农业攻关项目(编号:黔科合NY字[2012]3018号;黔科合NY字[2015]3025-1号);贵州省薯类产业技术创新人才基地资助项目;贵州大学研究创新基金项目

摘　　要：以新鲜白萝卜为原料,研究在不同的热风温度、热风风速和切片厚度条件下,白萝卜的热风干燥特性。通过试验数据拟合,比较7种数学模型在白萝卜热风干燥过程中的适用性。结果表明:白萝卜热风干燥以降速过程为主,无明显的恒速阶段。干燥温度、切片厚度对白萝卜的干燥速率影响较大,风速影响较小。干燥温度越高、切片厚度越薄、风速越快,干燥用时越短。通过比较各模型的相关系数(R^2)、卡方值(χ~2)和均方根误差(RMSE),结果显示Page模型的拟合效果最好,该模型的R^2为0.997 6、χ~2为2.615×10^(-4)、RMSE为0.014 6。且用模型外的试验数据进行验证,也表现出较好的拟合度。白萝卜的有效水分扩散系数(Deff)为7.560×10^(-10)~2.130×10^(-9),随着干燥温度、风速和切片厚度的增加而增大。白萝卜的干燥活化能为26.34kJ/mol。此外,还对白萝卜片干燥前后的色差进行了测定和分析,结果表明:在50~80℃时,随着温度的增加,干燥成品的L~*值逐渐降低,而b~*、a~*以及总色差ΔE~*值呈升高的趋势。With fresh radish as raw materials, the hot-air drying characteristics of fresh radish under different conditions of hot-air temperature, air velocity and slice thickness were investigated in this study. Then the fitting of experimental data and the applicability of 7 different mathematical models for the process of hot-air drying radish was compared. The results showed that the hot-air drying process of radish mainly occured in falling-rate drying period and the constant- rate period is not obvious. Hot-air temperature and slice thickness have a greater effect on drying-rate, relatively, while the effects of air velocity is less. The higher the temperature, the thinner the slice and the bigger the air velocity are, the shorter the drying time is. By comparing the coefficients （R2）, chi-square values （X2 ） and the root-mean-square error （RMSE） of each model, it was found that, among these models, the Page model is better than other models for describing the process of hot-air drying radish with Rz of 0.997 6, ）tz of 2.615X10 4 and RMSE of 0.014 6. It showed a good fitting be- tween the experimental and predicted values. With the increase of hot-air temperature, air velocity and slice thickness, the effective moisture diffusivity of radish increased from 7.560×10^-10 to 2.130×10^-9 , and the activation energy was 26.34 kl/mol. Finally, the color of dried products under different temperatures was examined and analyzed. Results showed that when the hot-air temperature increased from 50℃ to 80℃, the L＊ value showed a gradual decrease, while the values of a＊ , b＊ and total ehromatism △E＊ were reductive.

关 键 词：白萝卜 热风干燥 数学模型 有效水分扩散系数 色差 

分 类 号：TS255.3[轻工技术与工程—农产品加工及贮藏工程]