果蔬干燥过程的水分跨膜传输模型构建

为了较真实地描述干燥过程中果蔬组织内水分的传输情况,该文回顾了多孔介质干燥过程及相关研究模型。针对果蔬组织生理学结构及其特征,提出了干燥过程中水分在其内部的传输模型,并通过显微图像技术及热风干燥试验对模型中相关参数进行了试验测定。建立的水分跨细胞膜传递模型有效计算了水分在果蔬组织内部的跨细胞壁传输过程。研究结果表明:果蔬组织中约90%的水分存在于细胞内;干燥过程中水分迁移的过程为:首先细胞内液泡中的水分跨细胞膜流出至细胞间隙,该过程可通过水分跨膜传输通量(JV)来计算;然后,进入细胞间隙的水分可视为一般多孔介质内的孔道水分扩散过程用传统的孔道网络模型进行计算。

Transmission model of moisture transmembrane during fruit and vegetable drying process

In order to describe the moisture transport process in the cellular tissues of fruits and vegetables during drying, the mass transfer processes of porous media drying and their related mathematical models were reviewed in this article. Based on the physiological structures and characteristics of fruit and vegetable tissues, a new concept for mass transfer of drying process was presented and the related parameters in the mathematical model were determined by means of microscopic images and convective drying experiments. The transmembrane transport model developed in this article estimated the water transfer process form the intracellular to the intercellular spaces effectively. The results showed that about 90% of the water present in the cells. Sequence of water migration in plant tissue during drying process was that water outflows from vacuoleto intercellular space (pores), which could be estimated by the water transmembrane flux(JV); and then water diffusion inside the pores of plant porous media could be calculated by the conventional pore network models.