Pulsed UV-light penetration characterization and the inactivation of Escherichia coli K12 in model systems

Research pertaining to the evaluation of novel processing technologies has been on the rise as the number of notable foodborne outbreaks continues to garner the publics' attention. Ultraviolet (UV) light has been used for almost a century for the sanitization of water and surfaces. Pulsed UV-light involves the application of UV-light in quick bursts, which increases the instantaneous energy received by the product. The goal of this research was to characterize pulsed UV-light in terms of penetration depth, microbial inactivation, and temperature increase. Two different gelled materials, agar and whey protein isolate, were studied based on their opaqueness. Sample of the gel were taken as 2 mm thick sections and analyzed for the inactivation of E. coli K12, temperature increase, and amount of UV radiation received. The inactivation curves obtained indicated that the relationship between energy dose and inactivation was non-linear and the Weibull model was used to estimate these inactivations. Three approaches were undertaken to determine the model parameters. Each model had its advantages and disadvantages but in all three it was observed that broadband energy was not a suitable predictor of microbial inactivation.