Use of Enterococcus faecium as a surrogate for Salmonella enterica during extrusion of a balanced carbohydrate-protein meal

Andreia Bianchini, Jayne Stratton, Steve Weier, Timothy Hartter, Brian Plattner, Galen Rokey, Gerry Hertzel, Lakshmi Gompa, Bismarck Martinez, Kent M. Eskridge

Research output: Contribution to journalArticle

32 Scopus citations


Multiple outbreaks of salmonellosis have been associated with the consumption of low-moisture products, including extruded products. Therefore, there is a need for a nonpathogenic, surrogate microorganism that can be used to validate extrusion processes for Salmonella. The objective of this research was to determine if Enterococcus faecium NRRL B-2354 is an adequate surrogate organism for Salmonella during extrusion. Extrusions at different temperatures were done in material contaminated with both organisms. Results indicated that the minimum temperature needed to achieve a 5-log reduction of E. faecium was 73.7°C. Above 80.3°C, the enumeration of E. faecium showed counts below the detectable levels (<10 CFU g-1). Salmonella was reduced by 5 log at 60.6°C, and above 68.0°C the levels of this organism in the product were below the detection limit of the method. The data show that E. faecium is inactivated at higher temperatures than Salmonella, indicating that its use as a surrogate would provide an appropriate margin of error in extrusion processes designed to eliminate this pathogen. Attempting to minimize risk, the industry could validate different formulations, in combination with thermal treatments, using E. faecium as a safer alternative for those validation studies.

Original languageEnglish (US)
Pages (from-to)75-82
Number of pages8
JournalJournal of food protection
Issue number1
Publication statusPublished - Jan 1 2014


ASJC Scopus subject areas

  • Food Science
  • Microbiology

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