Evaluate Survival-Growth During Frozen, Refrigerated, or Retail Type Storage, and Thermal Resistance, Following Storage of Escherichia coli O157-H7 Contamination

Findings: Restructuring, marination, flavoring and tenderizing beef, although infrequently and at low levels, may internalize cells of foodborne pathogens, such as Escherichia coli
O157:H7, from the surface to the interior of products. If such contaminated products are mistaken as intact and unintentionally or intentionally undercooked, the internalized pathogen may survive during cooking. In this study, we evaluated the effects of restructuring, marination, flavoring and tenderizing ingredients on destruction of E. coli O157:H7, internalized in a ground beef model system, during cooking. Destruction of the pathogen in samples stored in aerobic or vacuum packages at -20oC, 4oC, and 12oC, was examined using three cooking methods (grilling, broiling, frying). Selected major findings of the studies include: restructuring with salt/phosphate minimized weight-loss during cooking but had a protective effect on the pathogen during cooking; salt/phosphate in combination with 0.4% lactic acid may be a useful alternative for restructured beef products; among the commonly used meat-tenderizers, calcium chloride in combination with acetic acid showed greater thermal inactivation of E. coli O157:H7 in product broiled to 65oC; among the cooking methods, broiling non-intact beef products to an internal temperature of 65oC was most effective; and, cooking of frozen products from their frozen state was less effective in thermal inactivation of the pathogen, compared to products stored at 4o or 12oC.