Impact of voltage and pulse delivery mode on the efficacy of pulsed light for the inactivation of Listeria

Citation
Hierro, E., Hospital, X. F., Fernández-León, M., Caballero, N., Cerdán, B., & Fernández, M. (2022). Impact of voltage and pulse delivery mode on the efficacy of pulsed light for the inactivation of listeria. Innovative Food Science and Emerging Technologies, 77, 102973. https://doi.org/10.1016/j.ifset.2022.102973
Abstract
Listeria innocua inactivation by pulsed light (PL) was evaluated at different settings and voltages to establish the best treatment conditions and post-treatment handling for further implementation of PL in the food industry. Fluences up to 0.2 J/cm2 were applied to superficially inoculated TSA agar plates (4.5–5 log cfu/cm2). Inactivation was calculated, and log-linear and Weibull models were applied. A fluence of 0.2 J/cm2 applied in a single pulse inactivated 3.8 log cfu/cm2, while sequential application of this fluence yielded an inactivation between 1.5 and 2.5 log cfu/cm2 depending on the delivery mode (consecutive flashing or with 5 min-holding times under ambient light or in the dark). Data from consecutive PL treatment were fitted with the Weibull model. No photoreactivation following PL was observed after 120-min exposure to ambient light in any of the conditions assayed. This study showed that flashing with a single pulse at higher voltage would offer the highest inactivation of Listeria. Industrial relevance: This study offered information of practical interest to establish pulsed light processing and post-processing conditions for the control of Listeria spp. in the food industry, for instance in ready-to-eat (RTE) products. The use of higher voltages provided higher inactivation and allowed minimizing the number of flashes. If sequential treatments are to be applied, the treatment is more effective if short holding times are kept between pulses. The post-processing illumination conditions do not influence the efficacy of PL treatment.
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Credit author statement Eva Hierro and Manuela Fernández were responsible for the research activity planning and execution, developed the design of methodology, performed data collection and analysis, and carried out the writing of the manuscript. Xavier F. Hospital and María Fernanda Fernández-León conducted part of the experiments and performed data collection and analysis. Natalia Caballero and Beatriz Cerdán conducted part of the experiments.
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