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United States Department of Agriculture

Agricultural Research Service

Research Project: MICROBIAL ECOLOGY AND SAFETY OF FRESH ON-FARM ORGANICALLY GROWN PRODUCE Title: Inactivation and injury of pathogens on intact beef treated with hydrodynamic pressure

Authors
item Patel, Jitu
item Macarisin, Dumitru
item Sangly, Gabriel -
item Murphy, Charles

Submitted to: Innovative Food Science and Emerging Technologies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 24, 2011
Publication Date: January 1, 2012
Citation: Patel, J.R., Macarisin, D., Sangly, G., Murphy, C.A. 2012. Inactivation and injury of pathogens on intact beef treated with hydrodynamic pressure. Innovative Food Science and Emerging Technologies. 14:38-45.

Interpretive Summary: Consumption of fresh or minimally processed food has increased over the last several years due to a demand from health concious consumers. Hydrodynamic pressure (HDP) processing is a non-thermal technology for improving the tenderness of intact beef. We evaluated the effect of HDP on the inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes attached to beef surface. Irridated beef cubes were inoculated with these individual pathogens (ca.4 log CFU/g) and treated with HDP. Surviving populations of E. coli O157:H7,S. Typhimurium, and L. monocytogenes were determined by spiral plating on Sorbitol MacConkey agar (SMAC), XLT4 agar, and modified Oxford (MOX) agar, respectively. The HDP treatment significantly reduced (0.55 -1.09 log CFU/g) these pathogens attached to intact beef. HDP also resulted in injury (ca. 0.5 log CFU/g) of E. coliO157:H7 and S. Typhimurium cells. Most cell injury occured at the cell membrane level as observed by Transmission Electron Microscopy (TEM). Results obtained in the present study show that HDP treatment, primarily evaluated for meat tenderness improvement, also reduces the number of viable pathogens attached to beef surface. However, additional hurdle treatment will be helpful to further reduce pathogens on beef surface.

Technical Abstract: The impact of hydrodynamic pressure (HDP) treatment on the inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes attached to beef surface was evaluated. Irradiated beef cubes were inoculated with these individual pathogens (ca. 4 log CFU/g) and treated with HDP. Surviving populations of E. coli O157:H7, S. Typhimurium and L. monocytogenes were determined by spiral plating on Sorbitol MacConkey agar (SMAC), XLT4 agar, and modified Oxford (MOX) agar, respectively. The HDP treatment significantly reduced E. coli O157:H7 (0.75 log CFU/g), S. Typhimurium)1.09 log CFU/g), and L.monocytogenes (0.55 log CFU/g) from beef surface. HDP-induced injury as determined by plating on non-selective media revealed that ca. 0.5 log CFU/g of E. coli O157:H7 and S. Typhimurium cells were injured. Most cell injury occured at the cell membrane level as observed by Transmission Electron Microscopy (TME). Results obtained in the present study show that HDP treatment, primarily evaluated for meat tenderness improvement, also reduces the number of viable pathogens attached to beef surface. Additional hurdle treatment will be helpful to further reduce pathogens on beef surface. Alternative technologies such as plasma spark should be further employed to produce hydrodynamic shock waves.

Last Modified: 4/23/2014
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