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.