• 基础研究 •

### 单片物料厚度对胡萝卜红外薄层干燥水分迁移的影响

1. 1.山东理工大学机械工程学院，山东 淄博 255091；2.山东理工大学农业工程与食品科学学院，山东 淄博 255091；3.中国农业大学工学院，北京 100083
• 出版日期:2017-07-15 发布日期:2017-07-11

### Effect of Single Material Thickness on Moisture Transfer during Infrared Thin-Layer Drying of Carrot

SUN Chuanzhu, SHI Dongyue, WANG Xiangyou, WEI Zhongcai

1. 1. School of Mechanical Engineering, Shandong University of Technology, Zibo 255091, China;2. School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo 255091, China;3. College of Engineering, China Agricultural University, Beijing 100083, China
• Online:2017-07-15 Published:2017-07-11

Abstract: In order to improve the drying rate vt and the quality of dried vegetables, in our previous work, single material thickness (h), material thickness (δ), drying temperature (T), power density (g) and radiation distance (L) were selected as factors affecting infrared radiation thin layer drying of carrot slices and optimized by one-factor-at-a-time method and orthogonal array design, and the analysis of variance showed that h value had a significant effect on the experimental results. In an effort to further explore the effect of h value on moisture migration during infrared thin layer drying, this study examined the transverse relaxation time (T2x), peak area (A2x) and peak ratio (S2x) as a function of single material thickness (h) and 4 other factors by low-filed nuclear magnetic resonance (LF-NMR). The mobility of free water dropped by over 60% in the middle stage of drying at each h value, with the moisture content tending to be zero and immobilized and bound water increasing not more than three times and three to six times, respectively. After 120 min of drying, the percentage of free water in the total peak area of water decreased to below 15% at each h value, while the percentage of bound water rose to above 65%, and the percentage of immobilized water showed two peaks. The effective water diffusion coefficient (Deff) was reduced by up to 30% with increasing h value. The Page model provided good prediction of changes in moisture ratio during infrared thin layer drying. Results from this study can provide a theoretical reference to further explore infrared drying of agricultural crops and to develop crop drying equipment.