## 3 Results and Discussion
### Oxidative Stability Assessment  
#### 3.3.1 Peroxide Value (PV)  
The peroxide value (PV) indicates information about the initial stage of fat deterioration and is a very important indicator used in food quality control and safety [50].  
Table 4 shows the effect of supplementing sausage formulations with bell pepper processing by-products (DYBPB and DRBPB) on the peroxide value during the 20-day storage period compared to the control and sausage samples to which sodium nitrite was added.  
In the initial stage of the degradation of fats and oils, the PV is measured to find out the level of hydroperoxide formed as a result of the oxidation process. Since oxidized products are generally toxic, the formation of hydroperoxides (the primary oxidation product of fats and oils) must be suppressed to ensure protection against the oxidation of fats and oils and the formation of secondary oxidation products, both from a food quality and food safety perspective [50].  
The PV was significantly higher in the control samples (SC, SDC, and SSC) compared to the samples with added sodium nitrite, DYBPB, and DRBPB during the 20 days of storage.  
During the 20 days of storage, peroxide index values were influenced by the heat treatments applied and the addition of the DYBPB and DRBPB to the sausage formulations (Table 4). Thus, with increasing doses of the DYBPB and DRBPB added to sausage formulations, a decrease in PV was observed. Lower PV values were recorded between the two sub-drugs used for the sausage samples with added DYBPB (0.327-4.773 meq O\({}_{2}\)/kg) compared to the samples with added DRBPB (0.257-4.367 meq O\({}_{2}\)/kg). This can be attributed to the higher bioactive potential of the DRBPB compared to the DYBPB.  
The heat treatment applied also influenced the PV value. Thus, for the smoked and oiled samples, lower values were recorded (0.327-4.534 meq O\({}_{2}\)/kg for SSDYBPB and 0.257-4.138 meq O\({}_{2}\)/kg for SSDRBPB) compared to those that were smoked and dried (0.429-4.773 meq O\({}_{2}\)/kg for DSDYBPB and 0.308-4.367 meq O\({}_{2}\)/kg). Significant differences (\(p<0.05\)) between the PV values of the investigated samples were recorded throughout the storage period. Comparing the PV registered for control samples with the addition of sodium nitrite (DCN and SCN) and sausage samples with the addition of the DYBPB and DRBPB can conclude that the DRBPB at doses providing a level of polyphenic compounds of 180-270 mg GAE/kg processed raw meat and the DYBPB at an amount providing a level of 270 mg GAE can replace sodium nitrite in meat products for both smoked and dried and smoked and cooked sausage formulations.  
In the previous study carried out by the authors of the article, evaluating the effect of tomato processing by-products added in different proportions to sausage formulas, a similar trend in the evolution of the primary oxidation process was obtained throughout the 20 days of storage with values obtained in the range 0.300-4.048 med O\({}_{2}\)/kg [12]. An inhibitory effect of the oxidation process was also reported by [PERSON] et al. [51] in their study on the evaluation of the antioxidant potential of onion and papika on meat. In addition, [PERSON] et al. [47] obtained an inhibitory effect in the primary oxidation process for sausage samples supplemented with various vegetables (bell peppers, carrot, spinach, purple cabbage, oyster mushroom), and [PERSON] et al. [52] followed the effect of using pomergnate peel extract in beef.