Solid–liquid expression of cellular materials enhanced by pulsed electric field

The mechanism of solid–liquid expression enhanced by pulsed electric field (PEF) is studied for agrofood cellular materials. The application of PEF induces the permeabilization of cellular membranes and facilitates the subsequent cells rupture by mechanical compression. The solid–liquid expression was preceded by mechanical pre-compaction of sugar beet slices under a constant pressure, application of PEF treatment under the same pressure, and prolongation of mechanical compression after the PEF removal. The periods of solid–liquid expression enhanced by PEF are studied on the basis of press-cake electrical resistance measurement. The rheological model of solid–liquid expression with a fracture element can be used to estimate the compressibility characteristics of press-cake treated by PEF. A simple empirical equation predicted well the compression ratio of press-cake at different parameters of PEF. With increase of electrical energy input the liquid emanation from press-cake was intensified up to some level of expression, which seems to correspond to the destruction of quasi totality of cells.