A multiphysics model for biological materials, coupling nonlinear viscoelastic deformation to water transport, was used to study forced convective drying of apple tissue samples (cv. Maigold). The accuracy of the model was verified with quantitative neutron radiography experiments, by comparing the total water loss, the transient water distribution profiles and the mechanical deformation. Both model simulations and experiments showed that the largest moisture gradients occurred at the air-tissue interface. The corresponding shrinkage behaviour was similar. Furthermore, the difference between simulation results from modelling the water exchange with the environment using a constant mass transfer coefficient or a spatially varying transfer coefficient from a flat-plate correlation was not significant, indicating that the drying kinetics were dominated by the water transport in the tissue rather than by the convective flow at air-tissue interface. The simulated results showed a satisfactory agreement with experimental observations. The validated model is clearly appropriate to be employed for optimization of convective drying processes of food. Industrial Relevance The paper adds a significant progress to the study the dynamics of drying (water transport and shrinkage) during dehydration of fruit tissue.
Bibliographical noteFunding Information:
The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 245288 . The authors would also like to acknowledge the Fund for Scientific Research — Flanders (Grant no. FWO G.0603.08 ), the K.U.Leuven (project OT 08/023 ) and the EC (FP7-226783 project InsideFood) for the financial support. Thijs Defraeye is a postdoctoral fellow of the Research Foundation — Flanders (FWO). The experiments were carried out at the NEUTRA beamline of the Paul Scherrer Institute, Villigen, Switzerland. We would like to acknowledge the contributions and support of the Paul Scherrer Institute NEUTRA support team.
- Nonlinear viscoelastic
- Wind tunnel