Analysis of bacterial inactivation by intense pulsed light using a double-Weibull survival model

Abstract

The objective of this study was to measure the inactivation efficiencies of intense pulsed light (IPL) on six types of bacteria and determine how the efficiency values are related to the spectral transmittance of IPL. All of the microorganisms exhibited up to 7-log CFU/mL reductions, and the double-Weibull survival model provided the best fit to the inactivation curves. We obtained 4D(v) values (which is the fluence required to inactivate 99.99% of viable cells) and z(v) values (which is the increase in lamp voltage required for a 1-log reduction of the 4D(v) value) for lamp voltages ranging from 800 to 1800 V (corresponding to total fluences from 0.00 to 11.41 J/cm(2)). The 4D(v) values for Bacillus cereus, Clostridium perfringens, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella Enteritidis, and Shigella sonnei for IPL treatment at 1800 V were 1.57, 0.66, 0.62, 0.79, 0.66, and 1.63 J/cm(2), respectively, while the corresponding z(v) values were 5553, 3590, 3201, 3678, 3672, and 6440 V, respectively. The variations in the sensitivity to IPL were related to differences in the transmittance of the microorganisms. A practical model was developed to predict the 4D(v) values of microorganisms based on their transmittance and the IPL lamp voltage.