Purpose: This study aims at quantifying the impact of chlorine concentration on P. aeruginosa planktonic cell inactivation to reach targeted population reduction in MPV washing bath.
Methods: The quantification of bacterial population decrease throughout lethal chlorine exposure (25 - 100 ppm) was determined on P. aeruginosa ATCC15442 at 4 temperatures (4 - 37°C) under continuous stirring conditions. Free active chlorine was generated using commercial household bleach and concentration was manually adjusted using colorimetric chlorine test trips. After sampling, immediate neutralization was performed using sodium thiosulfate and survivors were enumerated on nutrient agar to acquire inactivation kinetics or kill-curves. Kinetics were performed for three biological replicates and fitted using a Weibull-like model to determine a 3-log population reduction. The quantified impact of temperature on the population reduction during chlorine exposure was further determined with the 95% confidence intervals using a Bigelow-like model.
Results: Experimental kill curves underlined a slightly concave curve with a slight effect of temperature on bacterial reduction. At 8°C, the 3-log population reduction is reached after 95 min at 80 ppm. Note that the presence of by-product that could be generated with the use of chlorine and organic matter on bacterial destruction was not investigated.
Significance: Within the frame of SUSCLEAN European project on sustainable cleaning and disinfection in fresh cut food industries, a MatLab-based app was developed to quantify and quickly identify the combination of conditions ensuring no growth or inactivation of P. aeruginosa to enhance industrial outreach and further in silico test industrial relevant scenario in a few seconds.