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

• Published in: Innovative food science & emerging technologies 2022-05, Vol.77, p.102973, Article 102973
• Main Authors: Hierro, Eva, Hospital, Xavier F., Fernández-León, María Fernanda, Caballero, Natalia, Cerdán, Beatriz, Fernández, Manuela
• Format: Article
• Language: English
• Subjects: Inactivation; Listeria; Modeling; Photoreactivation; Pulsed light; Voltage
• ISSN: 1466-8564; 1878-5522
• DOI: 10.1016/j.ifset.2022.102973

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. 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 to minimise 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. •A single pulse at higher voltage was more effective than 5 pulses at lower voltage.•Log-linear and Weibull models yielded similar fit for holding times between pulses.•Treatment without holding times showed a slight tailing and better fit with the Weibull model.•No photoreactivation was observed after post-treatment exposure to light.