RESUMO
This study evaluated the potential of blue light-emitting diodes (LED) of wavelength 405 and 460â¯nm in combination with sodium chlorophyllin to inactivate Listeria monocytogenes and Salmonella spp. on cantaloupe rind. A cocktail culture of L. monocytogenes or Salmonella spp. strains was surface inoculated onto cantaloupe rinds to reach a final concentration of 4 log CFU/cm2 and dip-treated in a 100⯵M sodium copper chlorophyllin solution. The cantaloupe samples were then exposed to 405 or 460â¯nm LEDs at a total dose of 1210â¯J/cm2 and 5356â¯J/cm2, respectively, at 4 and 20⯰C. Results showed that the antibacterial efficacy against both pathogens on cantaloupe rinds between LED alone and LED with the chlorophyllin were statistically similar with bacterial inactivation ranging from 1.1 to 3 log CFU/cm2 in most of the cases or the difference was only minimal. A similar inactivation of 3 log CFU/cm2 was obtained in the case of L. monocytogenes and Salmonella spp. when illuminated by 405â¯nm LEDs while the inactivation of L. monocytogenes was higher than Salmonella spp. when illuminated by 460â¯nm LED. The δ value, a modified Weibull model parameter defined as the time (h) taken to reduce the bacterial population by 90%, was computed to compare the inactivation rates of the conditions. It was inferred that illumination with 405â¯nm LED required a lower δ value than 460â¯nm LED illumination (Pâ¯<â¯0.05) for the inactivation of L. monocytogenes at 20⯰C and Salmonella spp. at 4⯰C. Thus the findings of this study indicate a promising application of blue LEDs to inactivate these pathogens on the surface of cantaloupe, minimizing the risk of listeriosis and salmonellosis by consumption of cantaloupe.