Design and Development of a Pulsed Electric Field-Based Liquid Food Sterilization System

The pulsed electric field (PEF)-based sterilization is one of the novel technologies with good potential, especially for preserving liquid food such as fruit juices, milk, etc., by deactivating all forms of bacterial life while retaining the nutritional and sensory qualities. This paper presents a detailed study of the continuous processing scheme of the PEF-based liquid food sterilization using fresh orange juice inoculated with Escherichia coli (E. coli) bacterial solution inside a collinear-type sterilization chamber designed and developed at the authors’ laboratory. The percentage reduction in the bacterial count is studied with different suitable sterilization parameters, viz., load voltage, pulse repetition frequency, pulse width, and liquid flow rate. Over 88% bacterial reduction is achieved in the present study with the following sterilization parameters, which are 7.4 kV pulsed voltage, 200 Hz pulse repetition frequency, 4 μs pulse width, and 0.2 l/h liquid flow rate. The design of a five-stage solid-state Marx-type pulsed power source (PPS) intended to use specifically for PEF sterilization is also described in this paper. With a stage charging voltage of 2 kV, the developed five-stage PPS can generate a maximum 7.4 kV pulsed voltage across the sterilization chamber, generating a 13.4 kV/cm peak uniform electric field inside the treatment zone of the chamber.