基于反演法计算不同温度下小麦面团的水分扩散系数

水分扩散系数是食品加工过程中重要的物理参数。估算水分扩散系数的主要方法是基于第二菲克定律，但在应用这些定律的方式上存在显著差异。本研究采用Peleg、Weibull、双指数这三种常用的食品水分吸附动力学模型拟合了冻干面团在20、30及40℃时的吸湿曲线。在此基础上，通过COMSOL软件分别建立了瞬时平衡、对流、平行指数边界三种条件下的面团吸湿模型，并通过反演法计算出对应模型下的水分扩散系数。结果表明，Weibull模型和双指数模型决定系数均在0.999以上，较为适合冻干面团吸湿曲线的拟合；平行指数边界模型能较好的模拟出不同温度条件下冻干面团的吸附水分变化规律。同时证明了水分扩散系数随温度升高而变大，且不能被当作一个常数。

Calculation of Moisture Diffusivity of Wheat Dough at Different Temperatures Based on Inversion Method

Moisture diffusivity is an important physical parameter in food proceeding. The primary method used to estimate the water diffusion coefficient is based on the second Fick’s law, but there are significant differences in the way in which these laws are applied. In this work, three commonly used food moisture adsorption kinetic models, Peleg, Weibull and double exponential, were used to simulate the moisture absorption curve of freeze-dried dough at 20, 30 and 40 ℃. On this basis, the moisture absorption models of dough under three conditions, such as instantaneous equilibrium, convection, and parallel exponential boundary, were established by COMSOL software. The moisture diffusivity under the corresponding models was calculated using the inversion method. The results showed that the coefficients of determination of Weibull model and double exponential model were above 0.999, which were more suitable for fitting the moisture absorption curve of freeze-dried dough than other models. The variation law of adsorbed moisture of freeze-dried dough under varying temperature conditions was better simulated by the parallel exponential boundary model. Meanwhile, it was proved that the moisture diffusivity increased as the temperature went up and could not be regarded as a constant.