Interventions for Dry-Aged Beef Crusts Inoculated with Salmonella Heidelberg, Escherichia coli O157:H7, and Listeria monocytogenes 4b

Dry aging enhances unique steak flavors but may allow pathogenic bacteria and fungi to grow on the crust, which is discarded before sale. This study evaluated six interventions for reducing Salmonella enterica, Shiga toxin-producing Escherichia coli, and Listeria monocytogenes populations on dry-aged beef crusts to reduce the risk of incorporating crusts into other products for product enhancements. Crusts were spot-inoculated with rifampicin-resistant Salmonella Heidelberg, Escherichia coli O157:H7, Listeria monocytogenes 4b at 7.0 log CFU/mL. Six pre- and post-treatment crusts and negative and positive controls were sampled in triplicate (N=24). Treatments were hot-air drying (6 h, 60°C), sous-vide (2 h, 60°C), ambient water spray (1 min, 15°C), warm water spray (1 min, 50°C), 2% lactic acid spray (1 min), and UV-C light (30 min, 253.7 nm). Two cores per crust (25-mm diameter, total of 9.81 cm2 per crust) were excised, diluted, and spiral-plated onto selective and differential agar with 200 ug/mL rifampicin to determine pathogen log reductions. Sous-vide exhibited the highest log reductions of 5.4, 5.0, and 4.3 log CFU/cm2 for S. Heidelberg, E. coli, and L. monocytogenes, respectively. Other treatments’ reductions ranged from 0.1-4.9 log CFU/cm2, underscoring the variability of treatments in reducing foodborne pathogens on dry-aged beef crusts.