Effective moisture diffusivity modelling versus food structure and hygroscopicity

Effective moisture diffusivities (Deff) for model food systems presenting distinct structure and water sensibility were identified at various levels of hydration. Experimental moisture sorption kinetics with a controlled atmosphere microbalance were analyzed using distinct Fickian models with specific assumptions. Taking into account the deformation and the external resistance to mass transfer, higher values of Deff were identified specially for hygroscopic dense products in the range of high water activity. The difference of impact of the model assumptions on Deff depending on the investigated water activity range and food material was related to the structure and the equilibrium moisture sorption properties.