P3-60 Internalization and Post-cooking Survival of Non-O157 and O157:H7 Shiga Toxin-producing Escherichia coli in Blade Tenderized Beef Steaks

Wednesday, August 6, 2014
Exhibit Hall D (Indiana Convention Center)
Blaine Corliss, Texas Tech University, Lubbock, TX
Mindy Brashears, Texas Tech University, Lubbock, TX
J. Chance Brooks, Texas Tech University, Lubbock, TX
Alejandro Echeverry, Texas Tech University, Lubbock, TX
Jennifer N. Martin, Texas Tech University, Lubbock, TX
Amy Parks, Texas Tech University, Lubbock, TX
Siroj Pokharel, Texas Tech University, Lubbock, TX
Introduction:  Blade tenderization is commonly used to increase palatability in beef products. However, the risk of pathogen internalization and post-cooking survival ‒ particularly among serogroups of Shiga toxin-producing Escherichia coli (STEC) ‒ in blade-tenderized beef is a concern for beef processors.

Purpose: This study investigated the effects of biochemical meat properties on the internalization and post-cooking survival of individual non-O157 and O157:H7 STEC serogroups in blade tenderized beef steaks. 

Methods: Beef carcasses were selected to represent four USDA Quality Grade (QG; Choice or Select) × pH categories (dark cutter: 6.06 or non-dark cutter: 5.29 combinations. Strip loin subprimals from each carcass were divided into sections for inoculation (106 log CFU/cm2) with one of seven individual STEC serogroups (O157:H7, O26, O45, O103, O111, O121, and O145). Subprimals were stored for 14 d prior to blade tenderization, steak portioning, and cooking to various endpoint temperatures (50, 60, 71, and 85°C). Pathogen presence was evaluated prior to and after storage and cooking. 

Results: Neither carcass QG nor pH category influenced subprimal STEC attachment; however, STEC were greater (P < 0.05) on high pH steak surfaces.  Greater than 3.5 log CFU/g of STEC were present in raw internal steak samples. Serogroups O121 and O45 were not found in cooked samples from any endpoint temperature. However, O26, O103, O111, O145, and O157:H7 STEC were confirmed in the internal cores of steaks cooked to 50°C and O26 STEC was confirmed in a cooked sample cooked to an endpoint temperature of 71°C. None of the seven STEC serogroups was confirmed in samples cooked to 85°C. 

Significance: Blade tenderization promoted the internalization of STEC serogroups in non-intact beef products. Furthermore, the serogroups exhibited varied susceptibilities to commonly utilized endpoint cooking temperatures.