Chapter 9: High-intensity Pulsed Light Food Processing

Pulsed Light (PL) technology is an alternative to thermal treatment for killing pathogenic and spoilage microorganisms in foods, including bacteria, yeasts, molds, and viruses. The key component of a Pulsed Light unit is a flash lamp filled with an inert gas, such as Xenon, which emits radiation that ranges from UV (200 nm) to NIR (1100 nm). A high-voltage, high-current electrical pulse is applied to the inert gas in the lamp. The strong collision between electrons and gas molecules cause excitation of electrons, which then emit an intense, very short light pulse (1 μs to 0.1 s). The exact mechanisms by which PL causes cell death are not yet fully understood, but it is generally accepted that UV plays a critical role in microbial inactivation. Survival curves for the PL treatment display a nonlinear decline. In clear liquid substrates, PL inactivation is accurately described by the Weibull model. The effectiveness of PL is strongly influenced by the interaction of the substrate with the incident light. Therefore, the treatment is most effective on smooth, non-reflecting surfaces or in clear liquids. Overall, PL treatment brings exciting new opportunities to the Food Industry, ranging from water disinfection to the manufacture of safe, non-heat treated fruit juices, surface treatment of foods and food contact materials, or the terminal antimicrobial treatment of foods packaged in UV transparent materials. This technology could be used as a means to increase the safety and shelf life of foods, with no detrimental effects on their quality and sensory properties.