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United States Department of Agriculture

Agricultural Research Service

Research Project: NON-THERMAL AND ADVANCED THERMAL FOOD PROCESSING INTERVENTION TECHNOLOGIES

Location: Food Safety and Intervention Technologies

Title: Thermal inactivation of Escherichia coli O157:H7 and Salmonella on catfish and tilapia

Author
item Rajkowski, Kathleen

Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 21, 2011
Publication Date: January 17, 2012
Citation: Rajkowski, K.T. 2012. Thermal inactivation of Escherichia coli O157:H7 and Salmonella on catfish and tilapia. Food Microbiology. 30(2)427-431.

Interpretive Summary: The National Advisory Committee on Microbiological Criteria for Foods identified a need for data to determine the cooking parameter for finfish. Heat inactivation for Escherichia coli O157:H7 and Salmonella isolates was determined in catfish and tilapia. The D-10 value (time for 90 % reduction of the cells) for the Salmonella seafood and meat isolates on both finfish were the same and at 65 C the D-10 values ranged from 2.04 to 3.8 sec. The E. coli O157:H7 D-10 values on the finfish ranged from 3.3 to 4.2 sec at 65 C. The D-10 values for the E. coli O157:H7 and Salmonella on the finfish are much lower than the reported values in other food systems. The temperature increase for one log reduction (z value) was determined for both bacteria on tilapia and catfish and the z-value were within the literature reported range. Using the D-10 and z-values, cooking time and temperature can be obtained to assure pathogen free cooked finfish for consumers.

Technical Abstract: Thermal inactivation kinetics for three-stain mixtures of Escherichia coli O157:H7, and of Salmonella meat isolates, and a four-strain mixture of Salmonella seafood isolates were determined in catfish and tilapia. The D-10 values were determined at 55, 60 and 65 C using a circulating water bath. Linear regression was used to determine the D-10 values. The Salmonella seafood and meat strain D-10 values were the same. The Salmonella D-10 values on the finfish ranged from 425 to 450, 27.1 to 51.4, 2.04 to 3.8 sec (z = 4.3 – 4.8 C) at 55, 60 and 65 C, respectively. The E. coli O157:H7 D-10 values on the finfish ranged from 422 to 564, 45.2 to 55.5 and 3.3 to 4.2 sec (z = 4.48 – 5.0 C) at 55, 60 and 6 C, respectively. There was a statistical difference (P less than or equal 0.05) for the E. coli O157:H7 D-10 value on catfish and tilapia determined at 55 C. All other D-10 values using catfish or tilapia were similar. The D-10 values for the finfish were lower than the reported values in other food systems, but the z-values were within the literature reported range. These D-10 values can be used to determine cooking parameters of finfish.

Last Modified: 10/1/2014