## 3 Results and Discussion
### Microbiological Evaluation  
The impact of HHP treatments on the aerobic plate count (APC) of vacuum-packed wild red deer meat samples during storage is presented in Figure 2. The microbial counts on Day 1 and Day 14 demonstrate the effectiveness of HHP in reducing microbial loads and its influence on microbial growth during storage at 4 \(\pm\) 1 \({}^{\circ}\)C.  
On Day 1, a significant reduction in microbial counts was observed as the pressure increased, with the control (0 MPa) samples exhibiting the highest microbial load 4.67 log CFU/g. Samples treated at 150 MPa to 250 MPa showed moderate reductions compared to the control, while pressures of 300 MPa and above resulted in a significant decline in microbial counts, achieving levels below 1 log CFU/g at pressures of 500 MPa or higher. This dose-dependent microbial inactivation effect of HHP has been widely documented in the literature [27; 28], attributed to the ability of high pressure to disrupt microbial cell membranes, denature cellular proteins, and inhibit enzyme activity. HHP is generally more effective against Gram-negative bacteria (e.g., _Pseudomonas_ spp., Enterobacteriaceae) due to their thinner peptidoglycan layer, whereas Gram-positive bacteria (e.g., _Lactobacillus_ spp., _Listeria monocytogenes_) exhibit greater resistance to pressure-induced inactivation due to their thicker cell walls [29]. Bacteria typically present in chilled game meat include _Pseudomonas_ spp., _Lactobacillus_ spp., and members of the Enterobacteriaceaeiaceae family. Among these, _Pseudomonas_ spp. is the primary contributor to meat spoilage, while facultative anaerobic bacteria, particularly _Lactobacillus_ spp., tend to dominate in vacuum-packaged meat [30; 31].  
By Day 14, microbial counts in all samples increased due to storage-related microbial growth, with the control samples reaching 7.6 log CFU/g. In contrast, HHP-treated samples demonstrated significantly lower microbial growth compared to the control, with higher pressures (500 MPa and above) maintaining microbial counts below 5 log CFU/g. Notably, microbial counts in samples treated at 600 MPa remained at 2.83 log CFU/g, indicating the  
Figure 2: Means \(\pm\) standard error for aerobic plate count (log CFU/g) of vacuum-packed wild red deer meat samples subjected to different high hydrostatic pressure (HHP) treatments (150–600 MPa) and control (0 MPa) on Day 1 and Day 14 of storage at 4 \(\pm\) 1 \({}^{\circ}\)C. Means marked with different lowercase letters (a, b, c) indicate significant differences (\(p\) < 0.05) among different pressure levels, while means with different uppercase letters (A, B) indicate significant differences (\(p\) < 0.05) between storage periods (Day 1 vs. Day 14), based on [PERSON]’s HSD test.  
potential of high-pressure treatments to extend the microbial shelf life of vacuum-packed meat products. Previous studies have shown that pressures above 400 MPa are effective in suppressing microbial growth during chilled storage, as observed in beef [21].  
Additionally, microbial counts on Day 14 were consistently significantly higher than those on Day 1 for all pressure levels, reflecting microbial recovery or regrowth during storage. However, the extent of microbial growth was strongly dependent on the applied pressure, with higher pressures effectively limiting growth.