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Antimicrobial susceptibility and internalization of Salmonella Typhimurium in vacuum-tumbled marinated beef products
S Pokharel1, J C Brooks1, J N Martin2
1Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX, USA.
Abstract:
As the incidence of multidrug resistance (MDR) Salmonella enterica serotype Typhimurium is increasing, data regarding the antimicrobial interventions and pathogen internalization in marinated meat products are important. This study evaluated the antimicrobial intervention and internalization of Salm. Typhimurium in marinated beef sirloin steaks. Beef bottom sirloin flaps (IMPS #185A; USDA Select) inoculated (108 log10 CFU ml-1 ) with Salm. Typhimurium were sprayed (lactic acid (4%) and buffered vinegar (2%)) prior to vacuum-tumbled marination (0·35% sodium chloride and 0·45% sodium tripolyphosphate) for 30 min. Pathogen presence after antimicrobial spray, vacuum-tumbled marination, and translocation was determined by direct plating on Xylose Lysine Deoxycholate (XLD) agar with tryptic soy agar (TSA) overlay. The data imply varied internalization and antimicrobial susceptibility pattern of Salm. Typhimurium in marinated meat. Lactic acid (4%) spray (P < 0·0001) and buffered vinegar (2%; P < 0·0001) reduced surface populations of Salm. Typhimurium on inoculated beef sirloin flaps prior to vacuum marination. However, lactic acid treated sirloin flaps had greater reductions (~2 log10 CFU cm-2 ) than buffered vinegar when compared with control prior to vacuum marination. However, the translocation of Salm. Typhimurium following vacuum marination was not influenced (P < 0·333) by the application of a surface organic acid spray prior to marination.
Significance And Impact Of The Study:
As detailed in the Federal Register FSIS final rule (9 CFR part 317), vacuum-marinated, vacuum-tumbled meat products are not designated as 'mechanically tenderized'. As such, the internalization and potential survival of Salmonella spp. in marinated beef products is a major concern. These results highlight the internalization of pathogens in vacuum-tumbled meat products and emphasize the importance of considering these products as nonintact. Similarly, these data confirm the efficacy and utility of interventions prior to vacuum-tumbled marination. Further research is needed to identify additional strategies to mitigate internalization and translocation of pathogens into vacuum-marinated meat products.
Insights
Antimicrobial sprays like lactic acid and buffered vinegar effectively reduce surface Salmonella Typhimurium on beef before marination. However, these interventions do not prevent pathogen internalization during vacuum tumbling, highlighting risks in marinated meat products.
Area of Science:
- Food Microbiology
- Food Safety
- Antimicrobial Interventions
Background:
- Rising incidence of multidrug-resistant Salmonella Typhimurium necessitates understanding pathogen behavior in processed foods.
- Marinated meat products, particularly vacuum-tumbled beef, present unique challenges for pathogen control due to potential internalization.
Purpose of the Study:
- To evaluate the efficacy of antimicrobial interventions (lactic acid, buffered vinegar) on surface Salmonella Typhimurium.
- To assess the internalization and translocation of Salmonella Typhimurium in marinated beef sirloin steaks.
Main Methods:
- Beef sirloin flaps were inoculated with Salmonella Typhimurium.
- Antimicrobial sprays (lactic acid, buffered vinegar) were applied before vacuum-tumbled marination.
- Pathogen populations were quantified using direct plating on XLD agar with TSA overlay.
Main Results:
- Both lactic acid (4%) and buffered vinegar (2%) significantly reduced surface Salmonella Typhimurium populations.
- Lactic acid spray demonstrated a greater reduction in surface pathogens compared to buffered vinegar.
- Surface antimicrobial treatments did not significantly affect Salmonella Typhimurium translocation into the meat after vacuum marination.
Conclusions:
- Antimicrobial interventions are effective in reducing surface contamination prior to marination.
- Pathogen internalization remains a concern in vacuum-tumbled marinated beef, emphasizing the need to treat these products as non-intact.
- Further research is required to develop strategies mitigating pathogen internalization and translocation in marinated meat products.
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