Combination of different techniques for assessing PEF-treatment in plant and animal tissues

In the field of food innovation, pulsed electric field (PEF) technology has attracted increasing interest in recent years and has become one of the most attractive new non-thermal technologies due to its lower energy consumption and short treatment times. Although there is a considerable body of scientific work available, detailed information on detection and quantification of the effects of electroporation in complex and inhomogeneous multicellular systems, such as real food systems, is still limited. The effectiveness of PEF treatment depends on both process parameters and properties of the biological material, and the appropriate choice of methods to detect and assess changes caused by electroporation in food matrices is needed. A deeper insight into the changes that occur after electroporation and their relation to the complexity of the food matrices tested is of great value to develop new ideas for electroporation-based treatments in the food industry. Therefore, different characterization techniques were combined, namely electrical impedance spectroscopy, current-voltage measurements, and magnetic resonance imaging to evaluate the physical changes caused by PEF treatment in raw plant and skeletal muscles of interest for food and/or feed. Experiments were performed on potato tuber and apple fruit, as these plant tissues are most commonly used for industrial PEF applications, and on the chicken broiler Pectoralis major that was selected as reference skeletal muscle. Electrical impedance spectroscopy was used to measure the dielectric properties of the biological tissue before and after the application of pulses, as this is a common technique in food PEF applications to determine the degree of cell disruption. Another possible but rarely used technique is to analyse the voltage and current waveforms recorded during the application of electrical pulses. Analysis of electric current signals allowed us to detect changes in electrical properties of the cell membrane in real time. Advanced MR techniques were the third technique used to monitor the spatially-dependent effect of PEF treatment. In particular, the transverse relaxation time T2 provided evidence of the redistribution of water and solutes in the tissue as a function of the applied electric field during PEF treatment. The results of this study contribute to a better understanding of the effect of electroporation in complex and inhomogeneous multicellular systems, and provide important insights and calls for critical choice of electroporation assessment methods to optimize PEF treatment conditions.