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

      Hinds, Laura M.; Charoux, Clémentine M.G.; Akhter, Mahbub; O’Donnell, Colm P.; Tiwari, Brijesh K; Irish Department of Agriculture, Food and the Marine (Elsevier BV, 2019-09-21)
      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 different 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 log10 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 carried out 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 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 for 3 principal components. This study shows that UV-LED technology is effective as bactericidal and bacteriostatic technology, depending on wavelength used.
    • Principles and mechanisms of ultraviolet light emitting diode technology for food industry applications

      Hinds, Laura M.; O'Donnell, Colm P.; Akhter, Mahbub; Tiwari, Brijesh K; Department of Agriculture, Food and the Marine; 14/F/845 (Elsevier, 2019-04-13)
      The application of ultraviolet (UV) light to water, food contact surfaces and medical equipment for microbial inactivation is widely employed. To date, UV disinfection sources employed are primarily low-pressure and medium-pressure mercury lamps; emitting monochromatic and polychromatic light, respectively. Despite the widespread use of mercury lamps, there are multiple drawbacks associated with their use including; high energy consumption, large size which limits reactor design, high heat emission and the presence of mercury. Light emitting diodes (LEDs) have potential for use as a highly efficient UV decontamination technology. Recent advances in semiconductor development have resulted in UV-LEDs becoming more widely available. UV-LEDs emit monochromatic light, which enables customised UV-LED disinfection systems at specific wavelengths to be developed. The application of UV-LEDs for disinfection purposes has been studied in recent years, particularly with respect to water disinfections systems. In this review, studies relating to UV-LED food applications are discussed. Furthermore, the chemical changes induced in foods, as a result of UV treatment, together with advantages and limitations of the technology are outlined.