Inactivation of foodborne viruses dried and as bio-aerosolized droplets on food-contact surfaces by ultraviolet light

Transmission of foodborne pathogens can occur in food-processing environments through contaminated food-contact surfaces and aerosols leading to foodborne outbreaks. Improved sanitation approaches including ultraviolet (UV-C)-light technologies for optimal dose delivery to inactivate microorganisms are being researched. The objectives of this research were to determine the effects of UV-C LED at 255 and 279 nm and traditional 254 nm-UV-C against surface-dried and bio-aerosolized (UV-C LEDs only) hepatitis A virus (HAV), feline calicivirus (FCV) and Aichi virus (bioaerosols only) on model food-contact surfaces. Each surface-spread or bioaerosol-deposited virus on sterile ceramic (surface-spread only), stainless-steel, or glass surfaces were UV-C treated for up to 3.75 min (surface dose=0-48.83 mJ/cm2 (surface-spread) and 0-76.5 mJ/cm2 (bioaerosols) for HAV; 0-16.28 mJ/cm2 (surface-spread) and 0-51.0 mJ/cm2 (bioaerosols) for FCV and AiV). Recovered plaque counts from three treatments assayed twice were statistically analyzed using mixed model analysis of variance (MMAOV). The D-10 values (dose) for surface-spread HAV were 9.48±0.34, 14.53±2.52, and 7.26±1.93 mJ/cm2 using 254 nm-UV-C, were 4.60±0.91, 6.85±1.16, and 8.24±1.03 mJ/cm2 with 255 nm UV-C LED, and were 19.72±2.45, 26.05±0.60, and 9.12±2.08 mJ/cm2 with 279 nm UV-C LED on stainless-steel, ceramic, and glass, respectively. Surface-treated FCV showed D-10-values with 254 nm-UV-C of 3.65±0.06, 6.25±1.90, and 4.69±0.03 mJ/cm2, with 255 nm UV-C LED of 5.79 ±0.67, 5.97±0.32, and 5.25±2.01mJ/cm2, and with 279 nm UV-C LED of 7.53±2.11, 8.67±2.12, and 7.88±0.86 mJ/cm2, on stainless-steel, ceramic, and glass, respectively. The 279 nm UV-C LED D-10 values of bioaerosol-deposited HAV were 6.60±0.27 and 5.57±0.74 mJ/cm2, were 4.12±0.50 and 3.95±0.50 mJ/cm2 for FCV, and were 3.97±0.03 and 3.64±0.43 mJ/cm2 for AiV; and with 255 nm-UV-C LED were 47.39±7.40 and 40.0±2.94 mJ/cm2 for HAV, 35.36±4.04 and ii 40.16±7.95 mJ/cm2 for FCV, and 27.70±4.36 and 31.45±7.47 mJ/cm2 for AiV on stainless-steel and glass, respectively. These data indicate that generally higher 279 nm UV-C LED doses are needed for foodborne viral inactivation on food-contact surfaces compared to 255 nm-UV-C systems, and that viral-bioaerosols are more resistant to 255 nm-UV-C treatment than surfacedried viruses. These linear-model UV-C doses for viral inactivation on surfaces and as bioaerosol-deposits are useful for designing optimal UV-C systems for microbial inactivation.