中短波红外联合气体射流干燥提高茯苓品质  

Improving quality of Poria cocos using infrared radiation combined with air impingement drying

作　　者：张卫鹏[1,2] 肖红伟[1] 高振江[1] 郑志安[1,2] 巨浩羽[1] 张平[1,2] 方小明[3] 

机构地区：[1]中国农业大学工学院,北京100083 [2]中国农业大学中国农业机械化发展研究中心,北京100083 [3]中国农业科学院蜜蜂研究所,北京100093

出　　处：《农业工程学报》2015年第10期269-276,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金(31201436);无限极(中国)有限公司技改项目

摘　　要：为探索茯苓的干燥特性,改善茯苓干燥品质,该文将中短波红外联合气体射流干燥技术应用于茯苓块的干燥。利用Dincer模型拟合茯苓块干燥曲线,结合滞后因子、干燥系数分析干燥过程,并估算其水分有效扩散系数。给出Dincer模型的具体应用方法,求出并分析不同干燥条件下的毕渥数、水分有效扩散系数、传质系数。测定干燥后茯苓块的破碎率,及茯苓块浸出物的质量分数。对比分析Fick第二定律、Weibull函数、Dincer模型的优缺点。结果表明：1）与气体射流干燥相比,中短波红外联合气体射流干燥可缩短干燥时间,降低破碎率约18%,提高浸出物质量分数约1%;联合干燥过程亦为降速干燥;试验参数范围内,提高温度、风速均可提高干燥速率;2）滞后因子范围为1.0136-1.0202,且温度、风速越高,干燥速度越快,干燥系数越大;3）联合干燥技术的的毕渥数为0.0826-0.0982,小于0.1,表明干燥过程与边界的对流换热热阻有关。传质系数的范围为1.0319×10^-6-1.8003×10^-6 m/s。4）基于Fick第二定律、Weibull分布函数、Dincer模型计算的水分有效扩散系数变化趋势一致,均随温度、风速的升高而增加。Fick第二定律不要求干燥曲线呈＂指数＂形式,但仅适用于降速干燥。Weibull分布函数不考虑边界的对流换热热阻。Weibull分布函数、Dincer模型均可应用于非降速干燥,但二者的缺陷是干燥曲线需呈＂指数式＂拟合。综上所述,中短波红外联合气体射流干燥技术可提高茯苓品质,借助于Weibull函数、Dincer模型可从不同角度更全面地解读干燥过程。研究结果可为Dincer模型在茯苓生产加工过程中联合干燥技术的应用提供参考。Poria cocos has a long history of medicinal use in China. It is a kind of edible and pharmaceutical mushroom. Drying process usually affects the chemical and physical properties of the extracts of Traditional Chinese Medicine （TCM）. Quality control remains a big issue, affecting herbs, formulations, and even the practice of TCM.Poria cocos generally takes almost 7 days to be dried by traditional natural drying and is sensitive to microbial spoilage.Poria cocos blocks （15 mm × 15 mm × 15 mm） are also easily broken at the traditional hot air drying, such as oven drying. A promising solution to the problem is to take advantage of innovative process techniques including alternative drying methods in the pharmaceutical processing. In this work,poria cocos was dried by medium and short infrared wave drying combined with air impingement drying. Dincer’s model was also applied to the drying process and the lag factor （G）, drying coefficient （S）, Biot number （Bi）, moisture effective diffusivity velocity （Deff）, mass transfer coefficient （k） were analyzed. TheDeff was also calculated based on Weibull function and Fick’s second law, and there was difference among them. Combined with the GB-4857.5 T-1992Droping Test Method and Pharmacopoeia of People’s Republic of China, the broken rate and the extractum ofporia cocos under different drying conditions were tested. The main results were as follows： 1） Compared with air impingement drying, drying time was shortened by infrared radiation combined with air impingement drying technology, and It could reduce the broken rate by 18% and improve the extractum mass fraction by 1%; the drying process also occurred in the falling rate period; at the range of the testing parameters, the drying rate increased with the increase of temperature and wind speed, but there was not direct correlation between broken rate, extractum content and drying conditions. 2） TheG values of different drying methods were between 1.0136 and 1.0202, steady around 1. Dr

关 键 词：干燥 温度 模型 茯苓 Weibull函数 

分 类 号：TS255.1[轻工技术与工程—农产品加工及贮藏工程] TQ028.6[轻工技术与工程—食品科学与工程]