Masters Theses

Date of Award

5-2025

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science

Major Professor

Doris D'Souza

Committee Members

David Golden, Xiaofei Ye

Abstract

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.

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