Use of circuit analysis simulations in pulsed electric fields food processing

Abstract

In pulsed electric field (PEF) technology, treatment intensity during food preservation is defined by two processing variables: electric field and treatment time. These variables are evaluated by high voltage and current sensors located in the PEF system. Proper sensor location is very important in obtaining valid processing variables. This paper investigated the use of circuit analysis aided by PSpice™ (OrCAD™, Demo Version 9.1, Beaverton OR) software to evaluate the impact of voltage and current sensor location on the accuracy of electric field, pulse width, and energy calculations during PEF food processing. PSpice™ software was used to conduct the circuit analysis of a typical PEF electrical circuit and to analyze the behavior of the electrical transient delivered by the PEF circuit to a coaxial food treatment chamber. A saline solution ( σ=0.47 S/m at 20 °C) was used to verify the effect of sensor location in a PEF pilot plant-scale electric circuit. A pulse generator delivering slightly overdamped transients with charging voltages from 30 to 40 kV was used. Of the three electrical parameters, the most affected by improper placement of voltage sensors was the electric field, which can be measured at up to ∼10% higher than that experienced by the food in the PEF treatment chamber gap. Also, good agreement between the PSpice™ simulation and experimental results was verified. If the electrical behavior of the PEF system is not known and the sensors are inappropriately placed far from the PEF chamber, the validity of kinetic data and conclusions drawn on the effectiveness of certain processing conditions will be significantly limited.