Research backs high-power pulsed light technology as food safety tool

The research, published in the Journal of Food Safety by a team of Lithuanian scientists, found that use of the non-thermal technology was successful in reducing plate counts of bacteria such as Salmonella enterica serovar Typhimurium and Listeria monocytogenes.

No significant changes in meat lipid peroxidation or sensory characteristics were detected in chicken treated under non-thermal conditions, said the group from the Institute of Applied Research in Vilnius.

The scientists said the bespoke equipment they developed and data obtained could be used for the “advanced development of high-power pulsed light technique which could be used for nonthermal decontamination of different food matrices (fruits, vegetables, eggs shell, fish and meat) and food-related packaging surfaces…processing equipment for the food, medical and pharmaceutical industries.”​

High-power pulsed light is a technique that intense and short duration pulses of broad spectrum light ranging from 200 nm to 1,000 nm to cleanse surfaces. It was approved for food surface decontamination by the US Food and Drug Administration (FDA) in 1999.

Method​

The experiments employed a spread plate method to evaluate antimicrobial efficiency of high-power pulsed light on the foodborne pathogens in vitro and after inoculation on the surface of skinless chicken breast meat.

The team established that only ultraviolet light was effective in reducing bacteria counts. They exposed the samples to high-power pulsed light treatment - at 1,000 pulses for 200 seconds, with a, total ultraviolet light dose 5.4 J/cm2. This reduced the viability of S. Typhimurium and L. monocytogenes inoculated on the surface of chicken by 2–2.4 log10 (N/N0) colony forming unit (cfu)/mL. It was further found that total aerobic mesophils on the surface of meat were diminished by 2 log10 (N/N0) cfu/mL. All experiments were performed under nonthermal conditions of less than 42C.

The method used also prevented the recovery of S. Typhimurium and L. monocytogenes bacteria - a process known as photoreactivation. The high-power pulse light used had an advantage over conventional UV light as it “induces extensive and unrepairable DNA damage, remarkably increasing the efficiency of the treatment”,​ said the research.

Lipid peroxidation​

The study examined how far the pulsed light affected the organoleptic properties of the chicken though the process of lipid peroxidation. The team said that, in general, continuous UV light causes this process to occur because of the length of exposure time for the meat needed to kill bacteria. But they added that the high-power pulsed light “can minimise this effect due to the short pulse duration”.​

The high-power pulse technique must employ short exposures in order to be considered as a nonthermal process – adding that the issue of avoiding thermal effects required a “novel engineering approach and new design of equipment”.​

High-power pulsed light for decontamination of chicken from food pathogens: a study on ​antimicrobial efficiency and organoleptic properties by E. Paskeviciute, ​I.​ Buchovec and Z. Luksiene ​

Source: Journal of Food Safety​

doi:10.1111/j.1745-4565.2010.00267.x​