Integration of pulsed electric fields technology in the biorefinery of agri-food wastes and microalgae

Abstract

Recently, the idea of valorizing industrial agro-food wastes and microalgal biomass, through an efficient recovery of their major bioactive constituents to be used as ingredients in food, feed, pharmaceutical and cosmetic sectors, is gaining interest, due to the increasing demand of consumers for natural products. However, the extraction of these compounds is problematic, due to the presence of a “physical barrier” (cell wall/membrane) when removing intracellular substances. Pre-treatment stage (thermal, mechanical or enzymatic) to permeabilise cellular tissues and facilitate the diffusion of the intracellular compounds in the external medium are required, together with the use of large amount of organic solvents and long contact times. This lead to high energy consumption, the formation of undesired compounds as well as to the eventual degradation of the target molecules to be recovered. Physical pretreatments operations have been proposed in the last year to overcome these problems and among them Pulsed electric fields (PEF) technology has shown promising results as to obtain mild, sustainable and efficient permeabilisation of cell membranes with respect to conventional cell disintegration methods. PEF consists in exposing biological cells to repetitive short voltage pulses (μs – ms in width) with an electric field strength in the range 0.5 - 50 kV/cm and an energy input up to 150 kJ/kg, mainly depending on cell size and morphology. This technique exploits its potential via the “electroporation” of membranes, which rapidly favors the leakage of valuable compounds from the cells. ... [edited by Author]