Understanding the Behavior of Listeria monocytogenes in High Pressure Processed Meat Products: Resources for Process Validation

High pressure processing (HPP) is recognised as an interesting, nonthermal technology used to inactivate vegetative bacterial cells, enabling the in-package, cold-pasteurisation of food with limited negative effects on the organoleptic and nutritional traits. Commercial implementation of HPP has grown exponentially in the last two decades; with the meat industry being one of the food sectors taking the greatest advantage of this emerging technology within the hurdle technology approach. As a killing step (i.e. post-lethality treatment for ready-to-eat products) aiming to assure food safety, it should be considered a control measure and be included in the HACCP plan. The effect of HPP depends on the microorganism (i.e. species and strain, as well as the physiological state), the process parameters (pressure, holding time, and temperature) and product characteristics (including piezoprotective and sensitising agents). Therefore, the specific high pressure treatment needs to be designed, assessed, and validated for each particular product. Beside the quantification of the lethality of the treatment, the behaviour of surviving cells during the subsequent storage has to be taken into consideration. In this presentation, different approaches to carry out validation studies will be presented, particularly focused on Listeria monocytogenes in meat products. Besides scientific literature, product-oriented challenge testing and available predictive models are the main resources providing scientific evidences about the validity of the technology. The High Pressure Process Predictor (HP³), a user-friendly, on-line simulator, will be presented as a useful tool to assess the effects of HPP on pathogens in meat products.