摘要
为建立稳健、适用范围更广的哈密瓜片含水率预测模型,采用不同干燥方法(热风干燥(Hot Air drying,HA)和红外辐射干燥(Infrared drying,IR)),在相同温度水平下(50、60、70℃)对哈密瓜片进行干燥,采用低场核磁共振技术(Low-Field Nuclear Magnetic Resonance,LF-NMR)对比分析干燥过程的水分迁移规律及2种干燥方法间的差异,并结合化学计量学方法建立含水率预测模型。结果表明:无论HA还是IR,一定温度范围内高温有利于提高干燥速率,缩短干燥时间;且IR与HA相比干燥时间缩短20.0%~37.5%。经LF-NMR分析,在HA和IR过程中,自由水峰面积逐渐降低,不易流动水峰面积及结合水峰面积呈波动变化;自由水峰顶横向弛豫时间不断降低,不易流动水峰顶横向弛豫时间因干燥方式和干燥温度的差异呈不同的变化趋势;与HA过程中结合水峰顶横向弛豫时间逐渐降低不同,其在IR干燥初期短暂上升,后呈下降趋势。基于HA、IR数据集结合化学计量学方法建立的哈密瓜片含水率预测模型中,偏最小二乘回归(Partial Least Squares Regression,PLSR)模型具有更好的性能,模型预测决定系数R_(P)^(2) 大于0.99,表明PLSR结合LF-NMR可实现哈密瓜片含水率的快速检测,且不受干燥方法不同引起水分状态差异的影响。研究结果为基于LF-NMR和多加工手段的果蔬含水率预测模型的建立提供参考。
Intelligent drying is one of the most promising directions to preserve a wide variety of food and agricultural products in modern drying technology.It is necessary to real-time monitor the physicochemical properties of materials in the drying process,thereby regulating the drying parameters.Furthermore,the water state and the moisture content of materials are the key information to control the drying process.In this study,the hot air drying(HA)and infrared drying(IR)were used at the same level of temperature(50,60,and 70℃)to dehydrate the cantaloupe slices.A low-field nuclear magnetic resonance(LF-NMR)was utilized to analyze the moisture migration and its variation in the products during two drying processes.A robust prediction model of moisture content was established using chemometric methods,where the NMR parameters of samples were obtained by LF-NMR during HA and IR.The results showed that the drying temperature significantly affected the drying characteristics of cantaloupe slices,either HA or IR.The high temperature was beneficial to shorten the drying time,due mainly to the high efficiency of mass transfer during drying.A higher drying efficiency was achieved in the IR,compared with HA.The reason was that the infrared radiation in the IR can penetrate the material to realize internal heating.The IR shortened the drying time up to 20.0%-37.5%,at the same temperature level.In LF-NMR analysis,the bound water,immobile water and free water were detected in fresh cantaloupe.The curves of transverse relaxation time(T_(2))moved to the left of the coordinate during HA and IR process,indicating the degree of freedom of moisture was reduced in the sample.There were also some changes in the NMR parameters obtained from the T_(2) curves.Specifically,the peak of transverse relaxation time for the free water T_(23p) decreased steadily,whereas,that for the immobile water T_(22p) showed various change trends,due to the differences in drying method and drying temperature.Unlike the gradual decrease in T_(21p)(the peak of
作者
李琳琳
陈俊亮
段续
任广跃
Li Linlin;Chen Junliang;Duan Xu;Ren Guangyue(College of Food and Biological Engineering,Henan University of Science and Technology,Luoyang 471023,China;Henan Engineering Technology Research Center for Drying Technology and Equipment of Agricultural Products,Luoyang 471023,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2021年第2期304-312,共9页
Transactions of the Chinese Society of Agricultural Engineering
基金
“十三五”国家重点研发计划项目(2017YFD0400901)
河南科技大学博士启动金项目(400913480074)。
关键词
干燥
模型
哈密瓜
热风干燥
红外辐射干燥
低场核磁共振技术
drying
models
cantaloupe
hot air drying
infrared drying
low-field nuclear magnetic resonance
