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Modelling of drying kinetic, salt and water diffusion


Advanced modelling and simulation of ham in several dimensions has been performed using the simulation programme COMSOL Multiphysics, with various geometries and sizes. Cubic ham samples have been modelled, and salt and water contents validated with experimental results. Very good fit was obtained. Numerical relationships for the diffusion coefficients were found, in which both salting and drying depends on local salt and water contents. A full-scale ham was made in Simple Ware, and the ability of the programme to simulate larger, more advanced and complex ham geometries validated. Results were in accordance with theory; salt and water diffusion are depended on the size and shape of the product, resulting in internal gradients, and required longer time in the larger ham-geometry than in the small ones. Import of a geometry of a real ham from CT-scans was investigated, though even muscles could be imported, this part of the work could not yet be completed. Similar work shows that it is possible, and that it is possible to include expressions for ripening (pyrolysis and lipolysis) in the models. Changing boundary conditions were applied successfully.

In a different approach by NTNU the salt profile in the different muscles of the hams was determined by physical sampling at different stages in certain hams of the production. The geometry was transferred manually into a 2D-grid (Matlab) and the salt diffusion during salting and resting was simulated. The model showed good agreement with the measured salt profile. Based on the different section of the ham several 2D models can be summed up into a quasi-3D model in order to simulate salting and resting. The model can be used to investigate different salting regimes and to optimize the production with respect to reduced salt content and evenly distributed salt profile.