Pulsed UV light to decontaminate eggs


n the US 9% of all foodborne illnesses are associated with eggs, according to lead researcher Josh Cassar, doctoral student in animal science. By reducing the microbial load on eggs, foodborne illness outbreaks associated with eggs and poultry meat can be reduced. Researcher Paul Pat- terson, professor of poultry science at Penn State, says this technology has the potential to achieve equal or greater mi- crobial reductions in the absence of water or other chemical sanitizers, and the decontamination solutions currently avail- able and widely used in the poultry industry. Not only is this an interesting solution for the poultry industry in developed nations but it also presents an interesting water-less egg san- itizing technology solution in developing countries where water may be scarce. Table eggs are currently washed with detergent and rinsed with sanitizers in the US egg industry. Hatching eggs, similarly, can be washed, or treated with chemical antimicrobial rinses or sanitizers. While UV light has been utilised with both table and hatching eggs as an additional antimicrobial step, pulsed UV light results in more acute delivery of UV light resulting in a greater microbial kill.

UV light versus pulsed UV light Cassar explains that pulsed UV light delivers a much higher intensity of UV light to the surface of the eggshell and is therefore significantly more effective, resulting in a greater microbial reduction in a shorter period of time than conven- tional UV light treatment. “Pulsed UV light has a broad spec- trum (100-1100 nm) emitted from a xenon flashlamp that is delivered in a series of pulses (100 ns to 2 ms) with over 50% of the energy originating from the UV region (100-400 nm),” notes Patterson. “The main germicidal mechanism of PUV light is the formation of DNA thymine dimers as a result of UV exposure. Secondary germicidal mechanisms result from longer wavelengths in combination with the short pulses that produce localised heating and micro-vibration, respec- tively, that contribute to microbial cell membrane collapse and death,” he says. Cassar explains how the experiment worked using components of a commercial egg grader: “As the egg rotates on its long axis along the way, the entire surface

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Researchers at Penn State College of Agricultural Sciences in the US have discovered that pulsed ultraviolet (UV) light can be an effective means of killing pathogens found on eggshells. This is a valuable finding for the poultry industry.

of the eggshell is exposed to the pulsed ultraviolet light energy, and the 27 seconds of exposure in our experiment resulted in an acceptable germicidal response,” says Cassar. “At three pulses per second, each egg is exposed to nearly 90 pulses, and each pulse has a duration of 360 microseconds – an extremely short duration pulse.”

Researcher Joshua Cassar led the study at Penn State College of Agricultural Sciences in Pennsylvania, US.


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