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P1-175 Inactivation of Foodborne Bacteria on a Ball-shaped Surface Model Using Bacto Agar by UVC-Assisted Titanium Dioxide Photocatalysis

Monday, July 29, 2013
Exhibit Hall (Charlotte Convention Center)
Jeong Un Kim, Yonsei University, Seoul, South Korea
Keunyong Yang, Yonsei University, Seoul, South Korea
Sujeong Kim, Yonsei University, Seoul, South Korea
Yeh Wei Sun, Yonsei University, Seoul, South Korea
Jiyong Park, Yonsei University, Seoul, South Korea
Introduction: There is an increasing interest in the application of UVC-assisted TiO2-photocatalytic oxidation (PCO) reaction for the disinfection of food surfaces. Disinfection effects of the UVC-assisted TiO2-PCO on fruits and vegetables are difficult to evaluate because of their inconsistency in degree of contamination and surface properties. A unified food surface model needs to be developed to overcome this drawback.

Purpose: Objectives of this study were to develop a food surface model and to analyze disinfection effects of UVC-TiO2-PCO on bacterial load on the food surface model and morphological changes in bacteria during the treatment.

Methods: Ball-shaped food surface model was prepared using Bacto agar which is generally used as microbiological culture media. Foodborne bacteria such as Escherichia coli K12, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus were inoculated to the surface model and treated with the UVC-TiO2-PCO reactor. Microbial inactivation and morphological changes in bacteria after the treatment were evaluated.

Results: Bacteria treated with the UVC-TiO2-PCO reactor showed higher reduction in bacterial count compared to UVC alone or control (dark reaction). UVC-TiO2-PCO treatment reduced microbial counts by 4.5-6.0 log CFU/cm2 compared to 3.0-5.3 log CFU/cm2 reductions by UVC alone after treatments for 100 s. Dark reaction as a control showed 0.7-1.6 log CFU/cm2 reductions after 100 s. Gram-negative bacteria decreased rapidly from the beginning; however, Gram-positive bacteria showed initial time lag under the UVC-TiO2-PCO reaction. Structural damages of bacteria were detected more markedly as the reaction time increased.

Significance: The results validate that the food surface model using Bacto agar can be applied to investigate effects of surface disinfection and the UVC-TiO2-PCO reaction is effective to inactivate foodborne bacteria.

Back to: Poster Session 1 - Risk Assessment, Food Toxicology, Beverages & Water, Meat & Poultry, Dairy & Other Food Commodities, Food Defense, Communication Outreach & Education, Non-microbial Food Safety, General Microbiology, Epidemiology, Seafood, Microbial Foo
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