Dehydration of apple tissue: Intercomparison of neutron tomography with numerical modelling

A multiphysics model was applied to study the moisture loss accompanied by large mechanical deformation of apple tissue samples (Malus × domestica Borkh. cv. 'Braeburn') during dehydration. The model incorporated a water transport model and a nonlinear viscoelastic deformation model and was solved using the finite element method. Satisfactory model performance was indicated, based on a comparison of the total water loss, the transient water distribution profiles and the mechanical deformation profiles, measured using quantitative neutron tomography. This indicated that the numerical model is a viable alternative to (neutron) experiments. A particular advantage of the model, compared to the experiments, is that it allows to quantify the hygro-stresses during drying, which showed that during dehydration, the surface of the sample attempts to shrink but is restrained by the inner wet tissue. Although access to facilities which produce neutrons is limited, neutron imaging also showed large potential for studies on fruit dehydration, as accurate quantification of the water content was possible.