## 1 Introduction
It uses mathematical models built with data from laboratory tests to describe the growth or survival of given pathogens in food. Manufacturers are keen to acquire data in simplified experimental models where only the most critical factors are controlled [31]. Using mathematical models makes it possible to quantify the risk of infection by pathogenic microorganisms [32; 33]. For example, validated growth models of _L. monocytogenes_ based on the Baranyi equation allowed the prediction of _L. monocytogenes_ growth dynamics in fishery products upon various aerobic environments [34]. In another study, fourteen model curves of cured and uncured roast beef ham and roast turkey hams (RTE foods) made it possible to predict the growth of _L. monocytogenes_ by applying the primary model (Baranyi equation) [35]. Microbial risk assessment (MRA) is one of the most important topics that has emerged over the decades concerning food microbial safety. Establishing maximum or minimum acceptable tolerance levels is essential to the structure of food law enforcement. However, such levels must be established with a complete and realistic approach in the proposed mathematical models [36]. It was recognised that as experimental techniques are refined and adapted, mathematical modelling will become an indispensable tool to provide a detailed analysis of existing and anticipated problems relating to food safety [37; 38]. The veracity of this thesis confirmed the constantly expanding collections of growth/survival models of various microorganisms in different food types on publicly available online databases such as ComBase or Pathogen Modeling Program (PMP), both supported by the Agricultural Research Service of the United States Department of Agriculture (USDA). Each FBO is obliged to conduct microbiological tests to determine the product's shelf-life, including testing for compliance with the process hygiene criteria (PHC) and food safety criteria (FSC) set out in Regulation 2073/2005 [39]. Shelf-life tests provided for foods intended for direct human consumption (without the need for cooking) may also include an assessment of whether the product supports the growth of _L. monocytogenes_ (challenge tests) [40], planned as a laboratory test that assesses the pathogen's growth potential (\(\Delta\)) in artificially contaminated samples stored under foreseeable conditions. In a situation where the FBO intends to apply a limit of 100 CFU/g for a product that supports the growth of _L. monocytogenes_ (instead of the limit: not detected in 25 g), challenge tests can serve as a tool to obtain evidence for the competent authority that the product will indeed not exceed the 100 CFU/g limit or to set an intermediate limit that is low enough to ensure that the 100 CFU/g limit will not be met at the end of the shelf life [39; 41]. The most widely accepted guidelines for conducting microbiological challenge tests for _L. monocytogenes_ are procedures consistent with the EU Reference Laboratory for _L. monocytogenes_ (EURL Lm) and the International Organization for Standardization (ISO) 20976-1 standard [28; 42], the provisions of which we took into account when determining the methodology of our research. Constantly changing consumer food trends are forcing FBOs to create new food formulas for RTE products, which have a high share of the food market. The vacuum-packed, uncured RTE pork bars with dried plasma used in this study are a new product aimed primarily at consumers on a reduced diet, focusing on low-processed, high-protein products. Our study represents the first scientific report in the world in which uncured pork bars enriched with dried plasma were subjected to challenge tests to assess their safety regarding _L. monocytogenes_ hazard.