Impact of Liquid Food Volumes and Treatment Chamber Design on a High-Voltage Bipolar Square Pulse Generator

The efficacy of microbial inactivation in food items using a Pulsed Electric Field (PEF) is governed by pulse generator parameters, test chamber design, type, and volume of treated food items. This work deals with the simulation of a high-voltage PEF generator in the MATLAB platform to produce bipolar square voltage pulses. Before the circuit simulation, the pulse generator was modelled using the circuit averaging technique to ensure bounded output from the generator. Two distinctly dimensioned test chambers with parallel plate electrodes were fabricated in seven different volumes. Apple juice was considered for analysis and it was considered as an R–C circuit connected as a load across the PEF generator. The loading effect of apple juice on pulse voltage magnitude, electric field intensity, pulse power consumption, and specific energy dissipation were calculated for each volume in both test chambers. Detailed numerical computations were performed using Response Surface Methodology with Box-Behnken design to determine the relationship between food volumes and test chamber design on specific energy dissipation. It was observed from both the simulation and numerical computation that the test chamber with less electrode spacing provides better electric field distribution, higher specific energy dissipation, and lesser loading effect. For the validation of the simulation, a high-voltage bipolar square pulse generator was fabricated and the pulse was applied across apple juice sample. The results show that the number of microbes present in the treated sample is reduced compared to the untreated sample.