Diffusion Model for Apple Cubes Atmospheric Freeze-Drying with the Effect of Shrinkage

Atmospheric freeze-drying (AFD) could combine the advantages of both freeze drying (high product quality) and convective heat pump drying (lower process costs). A black box modelling approach, the diffusion model, was adopted and verified. Effective diffusivity coefficient and activation energy were used to cover the AFD multi-component diffusion mechanism. Coupled with the shrinkage factor diffusion model showed good prediction of the drying kinetics of 10 mm Idared apple cubes in the AFD process. Based on the estimation of presented prediction results, the diffusion model is capable of being applied to simulate AFD process for selected food products at constant and ascending process temperature (CT and AT) modes.