Anti-Listerial Effects of Satureja hortensis Essential Oils in Ready-to-Eat Poultry Meat Stored at Different Temperatures

Abstract

Listeria monocytogenes presents a considerable threat in cooked chicken products, especially those that are ready-to-eat, like deli meats. The aim of this study was to evaluate the antimicrobial efficacy of oregano essential oil (Satureja hortensis: SHEO) against L. monocytogenes contamination of ready-to-eat cooked chicken meat during storage. The chemical content of SHEO was identified using GC-MS, with its antimicrobial properties confirmed through Kirby-Bauer disk diffusion tests. GC analyses of the SHEO used in the study showed that it contained 14.69% carvacrol and 10.61% thymol. L. monocytogenes strain NCTC 5348 was inoculated into chicken meat through a dipping technique at concentration levels of 2 x 107 CFU/mL before and after application of SHEO solution (2 mu L/mL). Inoculated and SHEO-treated meat samples were stored -20 degrees C, +4 degrees C, and +10 degrees C under both traditional and vacuum packaging conditions for 28 days. Results indicated that SHEO significantly suppressed the growth of L. monocytogenes (approximately 1 log CFU/g), especially during the first 5-7 days at +4 degrees C in both packaging types. Vacuum packaging prolonged the antimicrobial effect of SHEO compared to conventional packaging at +4 degrees C and +10 degrees C, approximately 1.1-1.3 log CFU/g for 14 days. The antimicrobial activity of SHEO was limited to a range of approximately 0.1-0.5 log CFU/g at -20 degrees C compared to the control. These results suggest that combining essential oils with modern packaging methods can provide an effective approach to controlling cold-tolerant pathogens such as L. monocytogenes, thereby improving the shelf life and safety of ready-to-eat meat products.