Shining a light on antimicrobial technique for food

Penn State University researchers have developed a food sanitisation technique that uses pulses of light to destroy pathogenic microbes. The technique is a promising alternative to the chemical, heat and water-based antimicrobial technologies commonly used in the food industry.

Millions of people fall sick due to foodborne diseases each year around the world and despite ongoing technological developments and changes in food regulation the problem persists. Researchers are thus always on the lookout for new methods.

“Any improvements to prevent illness or save lives would be the best outcome of this research,” said Ali Demirci, professor of agricultural and biological engineering at Penn State and member of the research team. “We want to reduce the number of foodborne disease fatalities to zero.”

The use of pulsed light was described by the scientists in the Journal of Food Engineering. The study involved using high-intensity lights to treat E. coli, Salmonella Typhimurium, Listeria monocytogenes, Bacillus cereus, Aspergillus niger spores and Penicillium roqueforti spores.

The work was conducted in Demirci's lab in collaboration with Ed Mills, associate professor of meat science, and Josh Cassar, former doctoral candidate in animal science, who has since graduated and works as a food safety consultant.

Over the past two decades, the lab has applied the technique to a range of foods, including fruits, seeds, grains, cheese, milk, apple juice and multiple poultry products. The team even simulated production conditions to test the technology on eggs, using a conveyor devised to test the process in an industrial setting, with the xenon flashlamps designed to operate at commercial scale.

The food processing industry has long used low-intensity UV light for antimicrobial treatment in many applications but this relies on the principle of a continuous supply of light.

This new technique is different as it is “using pulsed light instead of continuous light, which takes advantage of the stored energy in a pulse, so we can deliver more power in less time”, Mills said.

The team’s technique is designed to be deployed on a food conveyor, where light pulses would be applied to the product as it passes by. The treatment delivers a higher intensity of light, because it is pulsed, which is claimed to result in a greater microbial reduction in a shorter period of time than conventional UV light treatment.

Pulsed light is an emerging technology, which could serve as an alternative to current antimicrobial interventions in the food industry but could also be applied more broadly in other antimicrobial applications, Cassar explained.

“Pulsed light is another tool in the toolbox,” Cassar said.

“When used in an appropriate setting, it can offset a chemical sanitiser or a water-based disinfectant. As with any novel technology, it will continue to develop and hopefully will provide us with an effective and efficient tool for sanitation in a range of environments and industries.”

The scientists hope that the light pulsing method will be adopted by the food industry as a method of food sanitisation. It could also have other applications more generally in sanitised environments such as hospitals, water treatment facilities and pharmaceutical plants, according to the researchers.

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