Inactivation of Salmonella in nonintact beef during low-temperature sous vide cooking

Abstract

Sous vide cooking is a method of food preparation in which food is vacuum sealed and cooked in a water bath that is set to a precise temperature and circulated by a sous vide device. Due to ease of use and affordability, this cooking method has grown increasingly popular in food service kitchens and domestic settings. However, low-temperature, long holding time sous vide cooking recommendations from manufacturers and chefs in popular press raise food safety concerns – specifically those for the preparation of nonintact beef products. The objective of this experiment was to address these concerns by validating a 5 log reduction of Salmonella spp. in sous vide cooked, nonintact beef steaks. Beef semitendinosus sliced into 2.54 cm steaks were internally inoculated to 7 log with Salmonella Typhimurium, Enteritidis, and Heidelberg via a needle inoculation pin pad. Steaks were individually vacuum sealed, and sous vide cooked at 46.1, 51.6, and 54.4°C. The minimum time measured for a 5 log reduction at 51.6 and 54.4°C was 150 and 64.5 min, respectively (P < 0.01). Additionally, a 7.28 log final reduction was achieved at 51.6°C after 322.5 min (P < 0.01). However, 46.1°C was only able to achieve a final reduction of 2.01 log (P < 0.01) after a holding time of 420 min. The results of this experiment validate in sous vide cooked products the time and temperature combinations provided in the USDA-FSIS Appendix A guidance for a 5 log reduction of Salmonella spp. in meat products. Moreover, more research is needed with other relevant foodborne pathogens to determine if sous vide cooking below Appendix A recommendations could lead to unsafe products.

Keywords

• Low cooking temperatures
• Non-intact beef
• Sous vide