Surface sanitation against foodborne pathogens in domestic environments: efficacy of a handheld ultraviolet C light...

Ensuring food safety is fundamental to protect public health, especially in domestic environments where food is handled daily. This two-phase study aimed to investigate the efficacy of an ultraviolet-C light emitting diode (UV-C LED) handheld lamp through in vitro disinfection tests and disinfection tests on artificially contaminated surfaces.

The UV-C LED-based lamp efficacy was assessed at different initial microbial contamination titers and several UV doses, and both American Type Culture Collection (ATCC), foodborne, and clinical strains were considered. The UV-C LED lamp demonstrated high efficacy (log10 reduction >1 log) against the standard bacteria strains tested using a UV dose of 21.77 mJ cm-2. The greatest efficacy was achieved against E. coli (k = 0.0232) followed then by Bacillus subtilis (k = 0.0225) against which a titer of <1 CFU ml-1 was achieved with a UV dose of 15.55 and 21.77 mJ cm-2, respectively. Cladosporium spp. (k = 0.001) showed higher resistance against UV treatment, where a 50.00 ± 14.14 inactivation rate % (%IR) was achieved by applying the highest UV dose (31.1 mJ cm-2). Compared with B. subtilis, isolated L. monocytogenes 490 showed similar susceptibility (k = 0.0236), unlike isolated Listeria monocytogenes 1484 (k = 0.0146), isolated Salmonella Infantis 43 072/20 (k = 0.0126), and isolated S. Infantis 29 673/20 (k = 0.0124), which showed greater UV resistance. Considering the results obtained on the surfaces (stainless steel, polypropylene, and glass), the type of surface material influenced the susceptibility of isolated bacterial strains. However, the presence of organic matter (5% fetal bovine serum) on the treatment surface did not significantly affect device decontamination efficiency by applying a UV dose of 15.55, 21.77, and 31.1 mJ cm-2. On both stainless steel and glass, a titer <1 CFU 169 cm-2 was achieved against all the isolated bacterial strains applying a UV dose of 31.1 mJ cm-2, except with L. monocytogenes 1484. Lastly, a titer <1 CFU 169 cm-2 was never achieved on polypropylene contaminated with L. monocytogenes 1484.

The use of a UV-C LED handheld lamp (peak wavelength 265 nm) could be an efficient disinfection method to be applied in domestic or small-scale food-processing environments, to reduce the cross contamination of food.