Location: Quality & Safety Assessment ResearchTitle: Performance and mechanism of standard nano-TiO2(P-25) in photocatalytic disinfection of foodborne microorganisms - salmonella typhimurium and listeria monocytogenes Author
Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2013
Publication Date: 11/17/2013
Citation: Long, M., Wang, J., Zhuang, H., Zhang, Y., Wu, H., Zhang, J. 2013. Performance and mechanism of standard nano-TiO2(P-25) in photocatalytic disinfection of foodborne microorganisms - salmonella typhimurium and listeria monocytogenes. Food Control. 39(2014):68-74. Interpretive Summary: Salmonella and Listeria are commonly detected in both raw and ready-to-eat meat products, and are responsible for many outbreaks of foodborne diseases in the USA. Nano-TiO2 has been demonstrate to be very effective to inhibit microbial growth under UV light, and is considered as a novel material that can be used for eliminating microbial pathogens from food. The objective of this study was to investigate the antimicrobial effects of nano-TiO2 particles on bacterial pathogens, Salmonella typhimurium and Listeria Monocytogenes, which are commonly found on raw and/or cooked poultry meat products. Our results show that nano-TiO2 effectively reduced the populations of either of the pathogens under UV light. Its effectiveness could be affected by nano-TiO2 concentrations and the initial microbial populations. L. monocytogenes was more resistant to nano-TiO2 treatment than Salmonella. Electronic microscopic images showed that under UV light, nano-TiO2 resulted in damage of bacterial cell walls, release of cell components, and subsequently the cell death. These results demonstrate that we can use nano-TiO2 to treat food products and reduce the risk of foodborne diseases by reducing pathogen populations and/or inhibiting pathogen growth.
Technical Abstract: In this paper, effects of disinfection by nano-TiO2 were studied on the two typical foodborne microorganisms, Gram-negative bacterium Salmonella typhimurium and Gram-positive bacterium-Listeria monocytogenes, in meat products. The performance of nano-TiO2 against the foodborne pathogens was evaluated using a suspension system and the cellular mechanism was determined by images observed under an transmission electronic microscope. Results show that under UV light, nano-TiO2 disinfected both Gram-negative and Gram-positive pathogens very effectively in the suspension system under UV light. L. monocytogenes was more resistant to nano-TiO2 treatment than Salmonella under UV light. Nano-TiO2 concentrations and the initial bacteria populations in the suspensions had significant influences on the effectiveness of photocatalytic disinfection against the pathogen, S. typhimurium. The optimum concentration was between 0.2g/L and 1.5g/L. Increased initial S. typhimurium population (from 104 to 107 CFU/mL) resulted in reduced effectiveness of the photocatalytic disinfection by nano-TiO2. Electron microscope images revealed that nano-TiO2 photocatalytic disinfection started with damage of bacterial cell walls; then cell components released or defused out of the cells; and subsequently the cells completely lost their morphology (dissolved) and died. These results demonstrate that nano-TiO2 is very effective against pathogens that can grow well on meat products and the effectiveness can be significantly influenced by nano-TiO2 contents and pathogen populations. The findings in these experiments provide the essential information for further developing a nano-metal-based, antimicrobial packaging system to improve safety of meat products.