Internalization of Salmonella enterica Serotype Typhimurium in Beef Products as Influenced by Vacuum Marination and Antimicrobial Interventions

Introduction: Though successful in improving palatability, the risk of pathogen internalization propagated by vacuum-tumbled marination has been documented. As the incidence of multidrug resistance(MDR) SalmonellaentericaserotypeTyphimurium is increasing, data regarding the antimicrobialinterventions and internalization of this pathogen in marinatedmeat products is important. 

Purpose: The purpose of this study was to determine the reduction of Salmonella Typhimurium on beef products intended for vacuum tumbled marination using organic acid interventions. Further, this projected aimed to evaluate the internalization or translocation of SalmonellaTyphimurium into marinated beef products following application of an organic acid.  

Methods: This study evaluated the efficacy of lactic acid(4%) or buffered vinegar(2%) as surface antimicrobial interventions to reduce SalmonellaentericaserotypeTyphimurium in beef sirloin flaps(n=24) intended for vacuum tumbled marination. Likewise, the translocation of SalmonellaTyphimurium into organic acid sprayed and marinated non-intact beef products was assessed. Beef sirloin flaps inoculated with Salmonella Typhimurium(10⁸ log CFU/ml) were sprayed with either lactic acid or buffered vinegar prior to vacuum tumbled marination(0.35% sodium chloride and 0.45% sodium tripolyphosphate) for 30 min. Salmonella presence following inoculation, organic acid application, and marination (internalized Salmonella) were evaluated. 

Results:  Salmonella was reduced by 2.4log CFU/cm² in post-inoculated surface attachment. The data indicated varied reductions and surface attachment (after vacuum tumbled marination) of SalmonellaTyphimurium among treated beef sirloin flaps. Lactic acid (4%) spray (P<0.0001) and buffered vinegar(2%; P < 0.0001) reduced surface populations of Salmonella on inoculated beef sirloin flaps prior to vacuum marination. However, reductions in surface populations were greater (~ 2log CFU/cm²) for lactic acid in comparison with buffered vinegar(P<0.0001). Alternatively, the internalization of Salmonella Typhimurium following vacuum marination was not influenced(P<0.333) by the application of a surface organic acid spray prior to marination.

Significance: These results highlight the internalization of pathogens in vacuumtumbled meat products and emphasize the importance of considering these products as non-intact. Similarly, these data confirm the efficacy and utility of interventions prior to vacuumtumbled marination yet highlight the challenge or mitigating internalization. Although surface interventions are efficacious, further research is needed to identify additional strategies to mitigate internalization of pathogens into vacuum-marinated meat products.