Evaluation of thermal process lethality for non-pathogenic Escherichia coli as a surrogate for Salmonella in ground beef

Authors: REDEMANN, MORGAN - Purdue University; BRAR, JAGPINDER - Purdue University; NIEBUHR, STEVEN - Iowa State University; LUCIA, LISA - Texas A&M University Health Science Center; ACUFF, GARY - Texas A&M University Health Science Center; DICKSON, JAMES - Iowa State University; SINGH, MANPREET - University Of Georgia

Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2017
Publication Date: 12/20/2017
Citation: Redemann, M.A., Brar, J., Niebuhr, S.E., Lucia, L.M., Acuff, G.R., Dickson, J.S., Singh, M. 2017. Evaluation of thermal process lethality for non-pathogenic Escherichia coli as a surrogate for Salmonella in ground beef. LWT - Food Science and Technology. 90:290-296. https://doi.org/10.1016/j.lwt.201712.037.
DOI: https://doi.org/10.1016/j.lwt.2017.12.037

Interpretive Summary: The United States Department of Agricultures’ Food Safety and Inspection Service has guidelines for inactivation of Salmonella in ready-to-eat (RTE) beef and poultry products, but additional means of thermal processing validation are needed. This study was conducted to determine if non-pathogenic Escherichia coli could be used as a surrogate for Salmonella as means to validate thermal processing parameters. To develop thermal death time curves, ground beef of varying fat contents (5, 10, 20, 25, and 30%) was inoculated with either Salmonella or E. coli and heat treated. At lower temperatures (54, 57, 60, and 63°C), the E. coli surrogates were more resistant to heat inactivation than the Salmonella in ground beef. At temperatures above 63°C E. coli surrogates and Salmonella were inactivated at similar rates, regardless of fat content. Greater reduction of E. coli surrogates in the ground beef post-lethality treatment suggest Salmonella inactivation at higher temperatures. Thus these E. coli surrogates can be successfully used to determine Salmonella inactivation in RTE meats products. Furthermore, non-pathogenic surrogate organisms present an opportunity to validate thermal processing without compromising food safety at processing facilities.

Technical Abstract: The United States Department of Agricultures’ Food Safety and Inspection Service (USDA-FSIS) has developed thermal lethality guidelines for non-typhoidal Salmonella inactivation in ready-to-eat (RTE) beef and poultry, but additional means of thermal processing validation are limited. Thus, the objective of this study was to determine if non-pathogenic Escherichia coli could be used as a surrogate for Salmonella as means to validate thermal processing parameters per Appendix A. To develop thermal death time curves, ground beef at varying fat contents (5, 10, 20, 25, and 30%) was inoculated with either Salmonella or E. coli and heat treated. At 54, 57, 60, and 63 °C across all fat levels, the E. coli surrogates had significantly greater (P < .05) decimal-reduction values (D-values) than Salmonella. Beyond temperature 63 °C, regardless of fat, E. coli surrogates and Salmonella were inactivated at similar rates (P > .05). Greater reduction of E. coli surrogates in the ground beef post-lethality treatment suggest Salmonella inactivation at higher temperatures. The most appropriate use of the E. coli surrogates would be for predicting, ensuring, and validating thermal processing for Salmonella inactivation at lower temperatures. However, effects of meat product composition and processing facility variables need to be further assessed.