Enhancing High-Pressure Bacterial Inactivation by Modified Atmosphere Packaging: Effect of Exposure Time and Cooked Ham Formulation

High-pressure processing (HPP) is a non-thermal preservation technology that can be applied as a control measure to inactivate pathogens and spoilage microorganisms once RTE meat products are packaged in a convenient format. HPP efficacy highly depends on product characteristics, but the impact of the sodium-reduced formulations and the effect of packaging atmosphere are scarcely known. The aim of the present work was to assess the effect of standard and sodium-reduced formulations from two different brands (A, B) under different packaging (vacuum and modified atmosphere packaging (MAP)) on the HPP inactivation kinetics of Listeria monocytogenes and spoilage lactic acid bacteria in cooked ham. Slices of cooked ham with standard and sodium-reduced formulations were inoculated with L. monocytogenes CTC1034 and Latilactobacillus sakei CTC746 (slime producer), packaged in vacuum and MAP (CO₂:N₂, 20:80), and pressurized (400 MPa/0–15 min) after 1 h (vacuum, MAP) or 24 h (MAP-exposed). Parameters of HPP inactivation kinetics were estimated by fitting the Weibull model to log reduction data. Results showed that the efficacy of HPP in sodium-reduced cooked hams tended to decrease compared to standard formulations, being the difference statistically significant for L. sakei. For L. monocytogenes, a significant enhancing effect of MAP was observed when HPP was applied just after packaging (1 h, MAP) of cooked ham of brand A. In the case of L. sakei, the inactivation by HPP was only enhanced in MAP-exposed samples. Therefore, the use of HPP as a control measure must be applied through a product-oriented approach considering the type of packaging and the time period between packaging and HPP.