Effectiveness of a novel UV light emitting diode based technology for the microbial inactivation of Bacillus subtilis in model food systems

The objective of this study was to assess the effectiveness of a novel UV multiwavelength light emitting diode (LED) based technology for the inactivation of B. subtilis in two model food systems. The LED based system was used to treat B. subtilis bacterial cultures using various combinations of UV wavelengths (285, 365, 405, 285/365, 285/405, 365/405, 285/365/405 nm) for two treatment durations (5 & 10 min). Bacterial enumerations, post-treatment analysis and SEM imaging were carried out. UV treatment at 285 nm was found to be the most efficient individual wavelength for inactivation resulting in > 6 log(10) reductions. Treatments at other wavelengths investigated also resulted in bacteriostatic effects. Synergistic effects were observed for treatment at a 285/405 nm combination in one model system. Growth kinetics were investigated using a modified Gompertz model and model fit was assessed by root mean squared error, accuracy factor and bias factor. Experimental data showed good fit with the model employed with RMSE values ranging from 0.01 x 10(-2) to 1.367 x 10(-2) for 5 min treatment, and 0.01 x 10(-2) to 0.210 x 10(-2) for 10 min treatment. Multivariate analysis was also carried out using principal component analysis and explained 100% of the variation observed using 3 principal components. This study shows that UV-LED technology is effective as a bactericidal and bacteriostatic technology depending on the wavelength used.