低水分面团体系解吸过程的水分扩散-对自由体积扩散理论适用性的评价  

Water Diffusion in Low Water Content Dough System during Desorption-Evaluating Applicability of Free Volume Theory

作　　者：李望铭 孔欣欣[1] 贾庆超 Li Wangming;Kong Xinxin;Jia Qingchao(College of Food Science and Engineering,Zhengzhou Institute of Science and Technology,Zhengzhou 450064)

机构地区：[1]郑州科技学院食品科学与工程学院,郑州450064

出　　处：《中国粮油学报》2023年第9期42-48,共7页Journal of the Chinese Cereals and Oils Association

基　　金：河南省教育厅高等学校重点研究项目(22B550021)。

摘　　要：自由体积扩散理论为模拟非Fick扩散过程提供了一条有效途径。研究采用动态水蒸气吸附分析仪(DVS)测定20、30℃时9个相对湿度(RH)下的水分解吸过程,根据Fick第二定律求出每RH步的水分扩散系数,据此拟合确定Vrentas–Duda(V-D)模型参数。然后根据建立的V-D扩散系数模型,计算面团的解吸过程并与实测结果比较。结果显示:低水分面团在解吸过程中表现出很强的非Fick扩散特征;尽管V-D模型能够很好拟合扩散系数随含水量的变化,所得模型参数K_(12)/γ_(2)、ξ、α_(2g)的值分别为0.221×10^(-3)cm^(3)/(g·K)、0.8、1.5×10^(-4)K^(-1),基本合理,但对水分解吸过程的预测并不理想。最后,就如何建立真实的扩散系数-含水量关系以及如何更好评估V-D理论的适用性进行了深入讨论。The free-volume theory of diffusion provides an effective approach for modeling non-Fickian diffusion.Water loss was followed using a dynamic vapor sorption(DVS) system under nine RH steps at 20 and 30 ℃,separately.Apparent water diffusivity in each RH step was extracted according to Fick's 2^(nd) law,and fitted to the V-D model,then,two necessary model parameters were optimized.The obtained diffusivity was used as a function of water content inversely to calculate water desorption to evaluate the applicability of the V-D model.The results suggested that non-Fickian diffusion had obviously occurred during the desorption of the low water content dough.Although the V-D model could well describe the variation of diffusivity with water content,and the parameters K_(12)/γ^(2)=0.221×10^(-3) cm^(3)/(g·K),ξ=0.8 and α_(2g)=1.5×10^(-4)K^(-1) were reasonable,the obtained diffusivity function cannot give a good prediction of water desorption.Finally,systemical discussions were conducted with respects to how to extract the true diffusivity-water content relation,and how to get a better evaluation of the applicability of the V-D theory.

关 键 词：扩散 自由体积 解吸 面团 

分 类 号：TS213.2[轻工技术与工程—粮食、油脂及植物蛋白工程]