PULSED ELECTRIC FIELD ASSISTED SOLID/LIQUID EXPRESSION OF AGRO-FOOD MATERIALS:TOWARDS A NOVEL ENVIRONMENTALLY FRIENDLY TECHNOLOGY

摘要

In this paper we analyse the kinetics and mechanisms of solid/liquid expression combined with a pulsed electric field (PEF).Experiments were performed with raw agro-food materials (slices of fresh carrots and apples,whole grapes),and with agro- food wastes.The layer of particles was formed in the laboratory filter press cell,connected to a PEF generator.The PEF treat- ment of different intensity (<1000 V/cm) and duration (10-300 ms) was applied before solid/liquid expression (as a prelrcat- ment) or during expression (intermediate treatment).The PEF application caused electropermeabilisation of cell membranes and enhanced considerably the solid/liquid expression from studied agro-food materials (from 30-50% before treatment to 70-85% after the treatment).The simplified empirical model of solid/liquid expression fitted the experimental data well for both untreated and electrically treated materials.The PEF treatment also influenced the quality of juices expressed from raw materials.The PEF treated juices were more limpid and pure compared to the untreated juices,probably due to selectivity of extraction from electrically permeated cells.Such juices can be purified and clarified more easily than untreated juices.Therefore,it can be speculated that the novel technology comprising the combination of PEF and solid/liquid expression will generate less quantity of industrial wastes compared to existing trans-formation technologies.