果蔬渗透脱水过程动力学研究

Osmotic Dehydration Dynamics During Fruits and Vegetables Pre-Drying Treatment

结合植物组织结构与流体传输过程机理建立了渗透脱水过程的一维质量传递数学模型。模型以植物细胞为传输过程的基本单元,考虑了各组分在细胞内、细胞外、通过细胞膜及胞间连丝的质量扩散,和由于体积收缩而导致的集流传输。以土豆为实验物料,在40℃恒温条件下,采用40%(质量百分比)的蔗糖溶液作为渗透液,进行渗透脱水实验,得到的实验结果与模拟结果十分接近,验证了模型的有效性。通过数值模拟可详细描述渗透脱水过程中土豆细胞内外水和蔗糖的质量浓度分布。并就能源与生产效率方面对"渗透-干燥"与"无预处理干燥"过程作了比较。

A one-dimensional mathematical model based on structure of the fruits and vegetables tissues and mass transfer mechanism was developed. The model with plant cell as a basic unit considered the mass diffusion and bulk flow of each constituent with the tissue during the osmotic dehydration. The driving force for the mass transfer was only assumed to be the concentration gradient. Potatoes were subjected to osmotic dehydration in 40% sucrose at 40~C. And a good quantitative agreement was obtained between the experimental and calculated results. Numerical results could describe the distribution of water and sucrose in the intracellular and extracellular volumes of potatoes during the osmotic dehydration and show the relationship between the change of cellular volumes and mass transfer of each constituent. In addition, the results showed osmotic dehydration had its drying time and energy advantages.