| Popis: |
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. |
