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Escherichia coli O157:H7 poses a threat to food industries and public heath in the United
States. Additional strains¸ including non-O157 shiga-toxin producing E. coli (STEC), are
rapidly becoming microorganisms of concern in fresh meats. Significant interest has been
placed on the effectiveness of current microbiological safeguards on the reduction of
STECs. <P>
The objectives of this project were to evaluate:
<ul><LI> the efficacy of spray interventions on the reduction of E. coli O1157:H7 and nonO157 STEC on the surface of non-intact beef subprimals and mechanically
tenderized steaks, and;</LI>
<LI> the survivability of E. coli O1157:H7 and non-O157 STEC on mechanically
tenderized steaks cooked to 50°C or 70°C. Escherichia coli O157:H7 and non-O157
STECs were evaluated separately.</LI></ul>
Findings: The reduction in prevalence of either bacterium was evaluated after inoculation (106 or 102 cfu/cm2) and spray treatment with water, 5% lactic acid, 2% hypobromous acid, or 2% peroxyacetic acid prior to vacuumed storage for 14 d. After 14 d, subprimals were needle tenderized and the presence of pathogens on steak surfaces (prior to cooking) and internal samples (from raw and cooked samples) were evaluated. Our data suggests that that spray treatments (water, 5% lactic acid, 2% hypobromous acid and 2% peroxyacetic acid), with packaging and storage, effectively reduced the target pathogens on subprimal surfaces and in steak cores. The data also suggests non-O157 STECs, compared to E. coli O157:H7 strains, exhibited greater acid and heat tolerance throughout the study.