Pulsed Electric Fields as Pretreatment for Subsequent Food Process Operations

Abstract

Despite the fact that pulsed electric field (PEF) can be used in food processing as a separate and independent process, it can also be utilized as a pretreatment method in order to enhance the subsequent process kinetics or to modify a quality of final products. The most energy-consuming processes (freezing, drying, extraction) that are applied in food industry are based on heat and/or mass transfer. These processes, next to juice pressing, are traditionally intensified by the means of mechanical, thermal, or enzymatic methods, which lead to disruption of a native cellular structure of raw materials. In general, the utilization of conventional pretreatment methods links to a high energy (and water) consumption and can cause degradation of valuable ingredients. Due to electrically induced disintegration of the cell membrane (and some other organelles), the progress of drying, osmotic dehydration, or freezing can be enhanced, and thus the specific energy consumption of aforementioned processes can be reduced. Moreover, pulsed electric field treatment can improve the extractability of nutrients, bioactive compounds, or pigments from the plant-based food or increase the yield of juice pressing. It is also possible to regard the cells as reactors and stimulate them by PEF application to produce de novo some bioactive compounds – which can be beneficial regarding further processing of foods as well. Therefore, PEF application can be used not only to enhance the kinetics of unit operations but also to shape and tailor the quality in order to produce designed food.