Microbial inactivation kinetics by pulsed light

Pulsed light (PL) is an emerging technology that has attracted attention by food scientists due to the desirable combination of energy-efficiency and capacity to achieve extremely fast microbial inactivation performances. PL-mediated microbial inactivation curves have been reported previously by many researchers built on culture-based methods. However, an increasing amount of literature has recently shown that PL can induce microbial cells to enter a viable but non-culturable (VBNC) state, which raises concerns over interpreting data from previously-published microbial inactivation studies and compels scientists to explore alternative or complementary use of other more appropriate approaches to determine microbial inactivation. It is envisaged that the coming years will be seen as a transition period where previously-published microbial culture-based kinetic studies will be re-analyzed from the point of view of applying new lethality indicators that will either confirm or modify our thoughts about the inactivation kinetics by PL as current state-of-the-art knowledge in this area only uses data generated by microbial culture-based methods. The present chapter presents an overview of the VBNC state in this context and constitutes the first attempt to identify suitable alternative indicators of PL-mediated microbial lethality. Specifically, it describes the battery of approaches that could possibly be used to address this VBNC issue along with reporting on the efficacy and appropriates of using different microbial kinetic death rate models for PL-treatments and its interpretation. It is envisaged that the information described in this chapter will impact positively on the food industry in the future.