Modeling the protective effect of water activity of a meat emulsion matrix model on Listeria monocytogenes inactivation by high pressure processing

High Pressure Processing (HPP) stands out as an effective preservation method for deactivating L. monocytogenes, a primary concern for both public health and the food industry. However, studies mention that the efficiency of the technology depends on the processing parameters and characteristics of the food matrix. The objective of this study was to build and validate a mathematical model that relates and characterizes the behavior of L. monocytogenes ATCC19111 as a function of HPP parameters and water activity (a(w)) in a meat emulsion model through response surface methodology. Processing parameters used were: pressure (400-600 MPa), a(w) (0.94-0.98), and holding time (180-420 s), according to the proposed Central Composite Rotational Design (CCRD). The relationship between the listed variables was described through a polynomial equation. According to the obtained equation that best fitted the data (R-2 94.54 %), the three variables influenced the inactivation of the microorganism, where a(w) showed the highest influence (p < 0.05), considering the range of this study. Processing pressure and holding time showed a positive influence on the inactivation of the microorganism. On the other hand, the pathogen inactivation decreased with the reduction of the a(w) in the emulsified meat product, showing a clear baroprotection of the microorganism by the lower a(w). The results highlight the negative influence of lower a(w) on the lethality of the microorganism when the product is subjected to high pressure. Therefore, to guarantee the effectiveness of the inactivation process of L. monocytogenes, the HPP implementation must be designed and validated considering the intrinsic characteristics of the product and processing parameters. The mathematical model created in this research may contribute to the industry on ensuring food safety, compliance with legislation, and process optimization.