Development of an integrated solid-state generator for light inactivation of food-related pathogenic bacteria

Abstract

This paper is concerned with the design and performance of a fully integrated solid-state Marx generator, which has been developed to drive a UV flashlamp for use in microbiological inactivation. The generator has an output voltage rating of 3 kV and a peak current rating of 2 kA, although the modular approach taken allows for a number of voltage and current ratings to be achieved. The generator is constructed using a number of series-and parallel-connected 1.2 kV insulated-gate-bipolar-transistor (IGBT) switched capacitors. Switching of the IGBT modules is controlled by an optical signal. Details are given of how the optimum IGBT gate-drive circuit is achieved using optical components and a pass-through wire to provide the required energies for individual IGBT modules. The generator is demonstrated as the driver of a UV flashlamp used for inactivation of food-related pathogenic bacteria such as E. coli and Salmonella. The performance of the Marx generator over a period of 10 6 pulses is examined, along with the changes that occur in the spectrum of the UV flashlamp during the same period.

Factors affecting the inactivation of micro-organisms by intense light pulses

“…The highest efficiency of the ILP will be reached if the food products are flashed as soon as possible after the processing steps where contamination can occur. In the case of fluid products, the same shading effect can be expected at high cell populations as was noted by Gashemi et al. (2003), a thorough mixing should alleviate this effect.…”

Pulsed-light system as a novel food decontamination technology: a review

“…Similar conclusions regarding reduced efficacy on a huge bacterial population in a contaminated sample were reached by Wuytack et al (2003), who postulated that heavily contaminated products might be less efficiently decontaminated because of the shadow effect. In the case of liquid products, the same shading effect can be expected in high cell populations (Ghasemi et al 2003). The optimum efficacy pulsed light was achieved when food products were flashed as soon as possible after processing, before any increase in the numbers of endogenous microflora.…”

“…From the results described by Gómez-López et al (2005b), it is clear that high decontamination effects (from 1.2 log to more than 5.9 log) of intense pulsed light with a pulse duration of 30 ms and pulse intensity of 7 J can be observed after 50 pulses on different microorganisms inoculated on agar media (Table 1). Ghasemi et al (2003) chose E. coli and Salmonella enteritidis to study the inactivation effects of pulsed light, applying 5-100 pulses with a spectral range of 200-530 nm to bacterial suspensions transferred into empty standard Petri dishes. Analysis of the illuminated samples indicated that both E. coli and Salmonella enteritidis showed a 9 log order reduction after treatment with 100 pulses of 9 J.…”

Bacterial Inactivation Using Low-Energy Pulsed-Electron Beam

“…The conventional sterilization approaches such as thermal and chemical processing are well applied, but more rapid and less damaging techniques are needed. Nonionization radiation, such as UV light source [3], [4] is also another alternative but it is time-consuming and requires line-of-sight application [5]. The electrical techniques in these applications include the use of pulse-electric and electromagnetic fields [6], [7] and various plasma processing such as corona discharge [8], [9] dielectric barrier discharge [10], resistive barrier discharge [11] and uniform-glow discharge plasma [12], etc.…”