Dual-porosity model of liquid extraction by pressing from plant tissue modified by electroporation

Abstract

One of the basic challenges in applying electroporation to tissues is the understanding of resulting structural property changes and mass transport properties in the treated material. In applying electroporation to plant tissue, the objective is in either achieving improved extraction of intracellular compounds or water out of cells, or facilitating otherwise impractical, impossible, or severely hindered introduction of molecules into cells. Understanding of and the ability to model solute and liquid transport phenomena in treated tissues is therefore of great importance, both in scientific terms as well as for practical purposes that are of interest to the food processing industry or biorefinery. Electrical and process parameters that are characteristic of a particular treatment protocol used to achieve the required mass transport enhancement in tissue should be connected, theoretically, with the resulting improvement in mass transport and structural changes in tissue. This theoretical link should be established in order to allow for optimization of the treatment protocols, thus saving energy, materials (e.g., extraction reagents or solvents), reducing time for post-treatment processing (e.g., diffusion or maceration stage), and improving the quality and safety of the final product. This chapter presents a modeling approach to understanding mass transport processes in electroporated tissues, whereby the mass transport process is mathematically linked to the structural property changes in tissue resulting from electroporation. The approach has been termed the dual-porosity model and should be considered as an illustration of the fundamental basis to a more comprehensive model connecting effects of electroporation on the biological membrane with its observable effects on the macroscopic level of tissue. To allow the reader immediate application and full comprehension of the model, the complete mathematical derivation and an analytical solution of the fundamental model equations are presented, supplemented by an extensive commentary on the theoretical basis and derivation of individual parameters of the model.