Comparison of microbial reduction effect of intense pulsed light according to growth stage and population density of Escherichia coli ATCC 25922 using a double Weibull model.

This study evaluated how the efficacy of intense pulsed light (IPL) was influenced by biological factors such as the incubation time and the population of Escherichia coli. According to the 4D value, the microorganisms in the exponential phase were more susceptible to IPL (0.51 J/cm), while those in the stationary phase were the most resistant (0.67 J/cm). The microorganisms in the exponential phase could have more critical DNA damage. In addition, the degree of inactivation was affected by the microbial population. When the population was 10 CFU/ml, a maximum 3.4-log reduction was observed after applying IPL at 12.5 J/cm. In contrast, a population with a density of 10 CFU/ml showed maximally 0.13-log reduction when IPL was applied at 18.7 J/cm. This large difference might have been due to cell distribution and aggregation. The study is expected to contribute to the analytical confirmation of the microbial reduction mechanism through non-thermal technologies.