Filtration diffusivity and expression behaviour of thermally and electrically pretreated sugar beet tissue and press-cake

The expression behaviour of a sugar beet tissue pre-treated thermally (at 50 and 70 degrees C) and electrically (by pulsed electric fields applied at 20 degrees C and after preheating at 50 and 70 degrees C) was studied at constant pressure (5 bar). The filtration-consolidation behaviour of slices' assemblies (press-cake of sugar beet slices) was studied and compared to that of disk sample. The application of a pulsed electric field (PEF) treatment (600 V cm(-1) during 10 ms) induces the electroporation of cell membranes and facilitates the expression process. It was demonstrated that after treatment of sugar beet tissue by heat (at 70 degrees C), PEF, and combined (heat and PEF) pre-treatments, the solid-liquid expression followed the filtration-consolidation behaviour for both disk sample and slices'. The computational semi-empirical model employed in this paper allows the determination of the consolidation coefficient, which characterizes filtration diffusivity. Adjustment of experimental and model data showed that the filtration-consolidation behaviour of the disk sample was similar to that of slices' assemblies. Model adjustment showed that experimental data reasonably well coincide with the model, which permits a good prediction of the compression behaviour of thermally and electrically treated tissue and press-cake. (C) 2012 Elsevier B.V. All rights reserved.