## 2 Materials and Methods
### Microbiological Analysis  
All microbiological analyses (determination of total viable count, _Pseudomonas_ spp., _Brochtrix thermosphacta_, lactic acid bacteria, and _Enterobacteriaceae_ spp.) were conducted based on official methods [24]. The determination of microorganisms was carried out using the spread plate method on nutrient media, specifically with the plate method. Prior to microbiological analysis, the samples were homogenized by mixing 10 g of frankfurter-type sausage sample with 90 g of sterile Ringer's diluent (Merck, Darmstadt, Germany). Homogenization was performed using a Stomacher (BagMixer(r), Interscience, Saint Nom, France) at room temperature for 60 s. The number of microorganisms per gram of sample was expressed as colony-forming units (CFUs) per gram. The microbial load of the samples was calculated using the surface spreading and incorporation methods in plates. Total viable count (TVC) was determined by the spread method on non-selective nutrient medium--plate count agar (PCA, Merck, Darmstadt, Germany). Incubation was carried out at 30 \({}^{\circ}\)C for 72 h. For the calculation of the total population of mesophilic aerobic bacteria per gram of food (CFU/g), all bacterial colonies that grew on the PCA nutrient medium were counted. Different microorganisms form colonies of varying sizes, shapes, and colors. The presence of _Pseudomonas_ spp. was also determined by the spread method on the selective nutrient medium cetrimide agar (Merck, Darmstadt, Germany) after incubation at 30 \({}^{\circ}\)C for 72 h. All colonies that grew on the plates were counted for the enumeration of _Pseudomonas_ spp. _Brochtrothrix thermosphacta_ was determined by the spread method on STAA agar base (Biolife, Milano, Italy) after incubation at 30 \({}^{\circ}\)C for 48 h, during which, purple-colored colonies were counted. Lactic acid bacteria were determined on MRS agar (De Man-Rogosa-Sharpe agar, Merck, Darmstadt, Germany). All colonies on the plates were counted after incubation at 30 \({}^{\circ}\)C for 96 h, while the determination of _Enterobacteriaceae_ spp. was carried out on VRBG agar (violet red bile glucose agar, Biolife, Monza, Italy), following incubation at 37 \({}^{\circ}\)C for 18-24 h. Two replicates of the appropriate dilution were carried out, while the microbiological analysis was performed in duplicate. Even though the present study focused on predicting spoilage-related rather than safety-related bacteria, all samples were analyzed using appropriate methods to detect the presence of pathogens (e.g., _Listeria_ spp., _Salmonella_ spp., _E. coli_, _Staphylococcus_ spp., Clostridia), as is routinely done for all HPP product batches in the collaborating meat industry. The following protocols and methods were employed: for _Staphylococcus_ spp., detection ISO 6888-2:2021 standards were followed [25], and _E. coli_ detection adhered to ISO 21528-2:2017, the horizontal method for the detection and enumeration of _Enterobacteriaceae_ spp. using a colony-count technique [26]. _Listeria_ spp. detection was performed by rapid screening methods using VIDAS(r) Solutions (LDUO/LMX), an automated food pathogen detection system specifically designed for _Listeria monocytogenes_ (VIDAS(r) Solutions LDUO/LMX, bioMerieux, Rio de Janeiro, Brasil), while for the detection of _Salmonella_ spp., the VIDAS(r) UP Easy SPT, a high-performance automated solution based on ISO 16140 AFNOR BIO-12/32-10/11 was used [27]. _Clostridium_ spp. was detected using SPS agar (sulphite-polymyxin-sulphadiazine agar, HiMedia Laboratories Pvt. Ltd., Maharashtra, India). These high-performance and standardized methods ensure the robust detection of pathogens in line with routine quality and safety monitoring in the collaborating meat industry. Results indicate that after the applied HPP conditions, no pathogens were detected, which agrees with the literature findings on the effect of HPP technology on pathogenic bacteria in similar meat products [28; 29].