摘要
为探究红外辐射干燥胡萝卜切片内部水分迁移特性,进行了辐射温度为60℃、切片厚度为5 mm时的胡萝卜切片红外干燥试验,并利用低场核磁共振波谱法对胡萝卜切片横向弛豫时间T2图谱进行了分析。试验结果表明,红外辐射干燥过程中自由水和半结合水的横向弛豫时间T2显著大于热风干燥;峰面积A0的衰减速度明显快于热风干燥,即干燥速率、水分变化梯度显著高于热风干燥;试验还得出了红外辐射和热风干燥胡萝卜切片的峰面积随干燥时间衰减趋势拟合方程。试验数据为进一步研究胡萝卜切片的精细化干燥和优化干燥工艺奠定了基础。
The drying process is one of the most important processes in food engineering. Infrared radiation drying is a process of non-steady-state heat and mass transfer,with the change of material moisture migration and quality characteristics. Heat and moisture transfers in fruits and vegetables during drying are complex processes,and knowledge of the moisture profile is fundamentally important for industrial processes. A better understanding of the mechanism of moisture transfer would help to improve product quality and the efficiency of drying process for fruits and vegetables. Low field nuclear magnetic resonance（ LF-NMR） has the technique advantages of nondestructive and non-invasive,which can be used to study the variation, distribution and flow of different phases state moisture in fruits and vegetables. The study of regularity of moisture migration was the foundation for optimizing drying parameters. With the radiation temperature of 60℃ and the thickness of the carrot slices of 5 mm,the tests of infrared drying were made. The spectra of transverse relaxation time T2 were analyzed by using the method of low field magnetic resonance spectroscopy（ LF-MRS） to explore the moisture transfer characteristics of carrot slices dried by infrared radiation（ IR）. The results showed that in comparison with hot air drying,the values of transverse relaxation time T2 of free water and semi-bound water from the process of infrared radiation drying were much greater,and the decay rate of the peak area A0 from the process of infrared radiation drying was also faster,which meant that the drying rate and moisture gradient were much higher. The fitting equations of the peak area A0 versus drying time was obtained with attenuation trend for carrot slices dried by infrared radiation and hot air. The results could lay a solid foundation for the further study on refinement drying and the drying technique optimizing for carrot slices.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2015年第12期240-245,共6页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金资助项目(31271908)
关键词
胡萝卜切片
水分迁移
横向弛豫时间
红外辐射
热风干燥
Carrot slices
Moisture transfer
Transverse relaxation time
Infrared radiation
Hot air drying
