食品科学 ›› 2017, Vol. 38 ›› Issue (13): 53-59.doi: 10.7506/spkx1002-6630-201713009

• 基础研究 • 上一篇    下一篇

单片物料厚度对胡萝卜红外薄层干燥水分迁移的影响

孙传祝,石东岳,王相友,魏忠彩   

  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

摘要: 为探讨胡萝卜红外薄层干燥条件下的水分迁移规律,选择单片物料厚度h、料层厚度δ、干燥温度T、功率密度g和辐射距离L为影响因素进行试验,并借助低场核磁共振技术研究了横向弛豫时间T2x、峰面积A2x和峰比例S2x的变化规律。结果发现,干燥中期,各单片物料厚度h的自由水流动性下降60%以上,而水分含量趋于0;不易流动水、结合水的水分含量增幅分别为不大于3 倍、3~6 倍。干燥至120 min,各单片物料厚度h的自由水峰面积占总水峰面积的比例下降至15%以下,结合水所占比例增大至65%以上,而不易流动水所占比例呈“双峰”现象。随着单片物料厚度h的增大,水分有效扩散系数Deff下降30%;发现Page模型可较好地预测红外薄层干燥中水分比的变化。本研究成果为进一步探讨农产物料的红外干燥规律及干燥设备的研发提供了理论参考。

关键词: 低场核磁共振, 红外辐射, 胡萝卜, 单片物料厚度, 薄层干燥, 水分迁移

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.

Key words: low-filed nuclear magnetic resonance (LF-NMR), infrared radiation, carrot, single material thickness, thin layer drying, moisture transfer

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