Survival of Listeria monocytogenes in Light and Full-Fat, Modified Atmosphere-Packaged, Sliced Greek Cheese over Shelf Life: Implications for Ready-to-Eat Food Safety

Listeria monocytogenes (Lm) represents a considerable hazard in ready-to-eat (RTE) foods, particularly for susceptible individuals. This study investigated the survival of Lm in modified atmosphere-packaged (MAP) semi-hard sliced Greek cheese, comparing full-fat and light varieties. Challenge testing was conducted, and key product characteristics, including MAP gas composition, background microbiota, sodium chloride concentration, fat content, water activity, and pH, were determined. While the tested sliced cheeses, under specific MAP and storage conditions, met EU regulatory criteria for RTE foods unable to support Lm growth, the pathogen persisted at low levels throughout the 6-month shelf life. This finding underscores a potential risk associated with temperature abuse or compromised packaging integrity, which could facilitate Lm proliferation. The observed survival highlights the importance of growth potential assessment, even in food matrices seemingly non-supportive of Lm. Given that post-pasteurization processing steps like slicing and MAP packaging can introduce contamination risks for vulnerable consumers, this study emphasizes the necessity of stringent hygienic practices to prevent Lm contamination. Food business operators (FBOs) must rigorously implement food safety protocols, including controlled storage temperatures, robust hygiene measures, and effective cross-contamination prevention strategies between raw and RTE products, to safeguard public health, protect brand integrity, and mitigate economic losses.