ARS | Publication request: Growth behavior of Escherichia coli 0157:H7, Listeria monocytogenes, Salmonella spp. and Pseudomonas aeruginosa on catfish fillets at abuse temperatures

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 9, 2012
Publication Date: June 25, 2012
Citation: Sheen, S., Pang, Y., Sommers, C.H., Kit, L. 2012. Growth behavior of Escherichia coli 0157:H7, Listeria monocytogenes, Salmonella spp. and Pseudomonas aeruginosa on catfish fillets at abuse temperatures [abstract]. IFT Meeting. June 25-28, 2012, Las Vegas, NV. 1:1.

Technical Abstract: The foodborne pathogens, Escherichia coli O157:H7 (Ec), Listeria monocytogenes (Lm) and Salmonella (Sal) may pose an occasional microbiological hazard on fresh fillets due to cross-contamination and temperature abuse at the production, retail, and consumer levels. Pseudomonas aeruginosa (Psa), a typical spoilage microorganism in seafood, is also included. The objective of this study was to characterize the growth behaviors of Ec, Lm, Sal and Psa on fresh catfish fillets at three abuse temperatures (8, 12 and 16 deg C for Ec, Lm, Sal; 8, 15 and 20 deg C for Psa). The catfish fillets were pre-treated with gamma radiation to eliminate the background microflora. Multi-strain cocktails of each pathogen were prepared and then inoculated onto the fillet surfaces to concentration 3 log CFU/g. The catfish fillet samples were then stored at three temperatures and the microorganism growth assessed during storage. The lag phases and growth rates were estimated using DMFit (Combase, Baranyi’s model). Results showed that the growth patterns, in terms of lag time and growth rate, are temperature dependent. At 8 deg C, the lag phases for Ec, Lm, Sal and Psa were 42.0 h, 25.4 h, 50.7 h and 59.2 h, respectively. The growth rates were 0.047, 0.046, 0.044 and 0.050 log CFU/g/h, respectively. In general, lag time decreased as storage temperature increased, but growth rate showed the reverse trend except for Psa. The maximum populations of all target microorganisms reached 8-9 log CFU/g in this study, however, Lm reached only 6.5 log CFU/g after 6 days at 8 deg C. Growth rate and lag phase as a function of temperature can be described by linear regression models. Results will contribute to risk assessment of catfish fillets.