Effect of lemongrass essential oil against multidrug-resistant Salmonella Heidelberg and its attachment to chicken skin and meat

Salmonella Heidelberg (S. Heidelberg) is a major pathogen implicated in foodborne outbreaks for which poultry products can serve as an epidemiological source. This study determined the efficacy of GRAS-status lemongrass essential oil (LGEO) against S. Heidelberg in vitro and on the pathogen's attachment to skin and meat. At first, employing in vitro assays, the effect of LGEO on multidrug-resistant S. Heidelberg multiplication and motility was examined. Biofilm inhibition and inactivation assays were also performed. The quorum-sensing modulating effect of LGEO was determined. In follow-up experiments, chicken skin or meat samples inoculated with S. Heidelberg were treated with various concentrations of LGEO at different time points at simulated scalding (54°C) and chilling (4°C) temperatures. The samples were incubated, and the surviving populations of S. Heidelberg were enumerated to determine if LGEO could be a potential processing aid in poultry operations. Duplicate samples were included in each treatment, and the experiments were repeated at least 3 times. Significant reductions of S. Heidelberg of at least 4.0 log(10) CFU/mL after 24 h in nutrient broth and poultry cecal contents was observed with 0.5% LGEO. Complete inhibition of motility, biofilm formation, and inactivation of pre-formed biofilms was observed with 0.15% LGEO (P ≤ 0.05). Concentrations of LGEO at 0.5% and 1% affected violacein production (P ≤ 0.05). On skin samples, all concentrations significantly reduced S. Heidelberg by 1.2 to 3.9 log(10) CFU/sample after 2 min at 54°C. We obtained a significant reduction of the pathogen in meat samples at 54°C and skin samples at 4°C with 2% LGEO. All concentrations significantly reduced S. Heidelberg from the treatment water kept at 4°C and 54°C (P ≤ 0.05). In conclusion, LGEO could potentially serve as a natural antimicrobial strategy in scalding and chilling waters to reduce S. Heidelberg during processing. However, additional studies are warranted before recommending its commercial use.