Treatment of Ultra Low UV Transmittance Fluids: Fundamentals and Applications

Danielle Marcelle G Ward, Tennessee State University


The continuation of foodborne pathogen outbreaks in milk has become a critical public health burden. Milk is prone to spoilage by microbes due to its rich nutrient content. Microbial disinfection is key in food production processes. Ultraviolet (UV) light technology is an energy efficient, sustainable, and cost-effective technique. The efficiency of UV-C irradiation as a non-thermal processing method for milk was investigated. This study aimed to validate UV-C irradiation inflicted DNA damage in pathogens and assessed the cytotoxicity of irradiated milk. Milk inoculated with two surrogate viruses (MS2, T1UV), Escherichia coli (EM), and two pathogenic bacteria (Salmonella Typhimurium (SM), Listeria monocytogenes (LM)) was treated with UV-C irradiation, followed by conventional analysis of DNA Damage, and cytotoxicity investigations. Contaminated milk samples were irradiated at 254 nm using a collimated beam (CB) small batch reactor or a Dean-flow system. Neutral Comet Assay was performed to assess the percent of DNA damage. Normal human colon fibroblasts (CCD-18Co) and normal mouse liver epithelial cells (AML12) were exposed to control and treated extract of samples. EC, ST, and LM were reduced by more than standard 5 log10 when irradiated by both UV-C systems at fluence levels of 0- 168 mJ˙cm-2. Milk extracts showed no cytotoxic effects on healthy colon and liver cells. The range of DNA damage for all bacteria was 39% to 72%. This study demonstrated that optimal inactivation of pathogens is achievable in milk, using a Dean-flow system which is desirable for commercial processing, indicating that UV-C processing is safe and efficient.

Subject Area

Biology|Food Science|Microbiology

Recommended Citation

Danielle Marcelle G Ward, "Treatment of Ultra Low UV Transmittance Fluids: Fundamentals and Applications" (2018). ETD Collection for Tennessee State University. Paper AAI10785208.